From fb81e9c1aa3c4afa6bed5e09165b4e314e574346 Mon Sep 17 00:00:00 2001 From: Renat Nurgaliyev Date: Mon, 15 Jun 2026 18:13:46 +0200 Subject: [PATCH] Update explanations --- README.md | 28 + explanations.json | 7974 ++++++++++++++++++++++----------------------- 2 files changed, 4015 insertions(+), 3987 deletions(-) diff --git a/README.md b/README.md index ab637d4..047ae90 100644 --- a/README.md +++ b/README.md @@ -68,6 +68,27 @@ BNetzA replaces the file in place across editions, so the URL is stable; the fetcher detects updates via the HTTP `Last-Modified` header. +## Exam aids (Hilfsmittel) + +BNetzA publishes an official aid sheet that candidates **are allowed to +use during the exam** — you do not have to memorize anything it +contains: + +- [`Hilfsmittel_12062024.pdf`](https://www.bundesnetzagentur.de/SharedDocs/Downloads/DE/Sachgebiete/Telekommunikation/Unternehmen_Institutionen/Frequenzen/Amateurfunk/AntraegeFormulare/Hilfsmittel_12062024.pdf?__blob=publicationFile&v=3) + +It bundles the BNetzA frequency-allocation table (band limits, usage +parameters, and maximum power per class), the IARU band plans, the +German *Rufzeichenplan* (call-sign series → class plus the +international suffixes like `/m`, `/mm`, `/p`), and the *Formelsammlung* +(formula collection) together with constants and material tables. It +does **not** contain foreign-country prefixes (*Landeskenner*), +Q-codes, or the phonetic alphabet — those remain memory items. + +Questions whose answer can be read or derived from this sheet carry a +**Hilfsmittel** note in their explanation (see below), so you can tell +when something is a lookup in the exam rather than something to learn +by heart. + ## See also - [**50ohm.de**](https://50ohm.de/) — community-maintained @@ -109,6 +130,13 @@ on this: questions without an entry just show no explanation block. Entries with `confidence < 7` render a small "low confidence" badge so learners know the reasoning is provisional. +Where a question's answer is available in the official exam aid sheet +(see [Exam aids (Hilfsmittel)](#exam-aids-hilfsmittel)), the explanation +appends a short **Hilfsmittel** note — for example pointing at the +frequency-allocation table, the IARU band plan, the Rufzeichenplan, or +the Formelsammlung — to flag that it is a lookup you may consult during +the exam rather than a memory item. + `EXPLANATIONS.md` is the editorial contract: schema, sourcing guidance, confidence scale, and the workflows an AI agent should follow when asked to add or improve entries. diff --git a/explanations.json b/explanations.json index 06c9a5d..bb65165 100644 --- a/explanations.json +++ b/explanations.json @@ -1,10502 +1,10502 @@ { "AA101": { - "revision": 1, + "revision": 2, "explanation": "Impedance is the AC form of resistance, including resistive and reactive parts, so it is measured in ohms just like resistance.", - "source": "https://50ohm.de/A_spule_2.html", + "source": "https://50ohm.de/NEA_spule_2.html#AA101", "confidence": 8 }, "AA102": { - "revision": 1, + "revision": 2, "explanation": "Charge is current integrated over time; one coulomb is one ampere-second, so As is the practical unit here.", - "source": "https://50ohm.de/EA_ladung_energie.html", + "source": "https://50ohm.de/NEA_ladung_energie.html#AA102", "confidence": 8 }, "AA103": { - "revision": 1, + "revision": 2, "explanation": "Energy is power over time, so it can be expressed as joules in SI terms or as watt-hours in practical electrical use.", - "source": "https://50ohm.de/EA_ladung_energie.html", + "source": "https://50ohm.de/NEA_ladung_energie.html#AA103", "confidence": 8 }, "AA104": { - "revision": 1, + "revision": 2, "explanation": "Symbol rate counts transmitted symbols per second, and that rate is measured in baud.", - "source": "https://50ohm.de/NEA_datenuebertragungsdrate.html", + "source": "https://50ohm.de/NEA_mehrwertige_verfahren.html#AA104", "confidence": 8 }, "AA105": { - "revision": 1, - "explanation": "For power ratios, gain in dB is 10 log10(P2/P1); 10 log10(40) is about 16 dB.", - "source": "https://50ohm.de/A_dezibel_2.html", + "revision": 3, + "explanation": "For power ratios, gain in dB is 10 log10(P2/P1); 10 log10(40) is about 16 dB. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_dezibel_2.html#AA105", "confidence": 8 }, "AA106": { - "revision": 1, - "explanation": "A 16 dB power gain is approximately 40 times; with 1 W drive the output is about 40 W, below the 100 W maximum.", - "source": "https://50ohm.de/A_dezibel_2.html", + "revision": 3, + "explanation": "A 16 dB power gain is approximately 40 times; with 1 W drive the output is about 40 W, below the 100 W maximum. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_dezibel_2.html#AA106", "confidence": 8 }, "AA107": { - "revision": 1, - "explanation": "1 W is 0 dBW, and a 10 dB amplifier raises the power level by 10 dB, giving 10 dBW.", - "source": "https://50ohm.de/A_dezibel_2.html", + "revision": 3, + "explanation": "1 W is 0 dBW, and a 10 dB amplifier raises the power level by 10 dB, giving 10 dBW. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_dezibel_2.html#AA107", "confidence": 8 }, "AA108": { - "revision": 1, - "explanation": "dBW is referenced to 1 W, so 20 dBW means 10^(20/10) W = 100 W = 10^2 W.", - "source": "https://50ohm.de/A_dezibel_2.html", + "revision": 2, + "explanation": "dBW is referenced to 1 W, so 20 dBW means 10^(20/10) W = 100 W = 10^2 W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_dezibel_2.html#AA108", "confidence": 8 }, "AA109": { - "revision": 1, - "explanation": "The amplifier output is 10 W; in dBm that is 10 W = 10000 mW, and 10 log10(10000) = 40 dBm.", - "source": "https://50ohm.de/A_dezibel_2.html", + "revision": 3, + "explanation": "The amplifier output is 10 W; in dBm that is 10 W = 10000 mW, and 10 log10(10000) = 40 dBm. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_dezibel_2.html#AA109", "confidence": 8 }, "AA110": { - "revision": 1, - "explanation": "dBm is referenced to 1 mW: 0 dBm is 1 mW, +3 dB is about double or 2 mW, and +20 dB is 100 times or 100 mW.", - "source": "https://50ohm.de/A_dezibel_2.html", + "revision": 3, + "explanation": "dBm is referenced to 1 mW: 0 dBm is 1 mW, +3 dB is about double or 2 mW, and +20 dB is 100 times or 100 mW. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_dezibel_2.html#AA110", "confidence": 8 }, "AA111": { - "revision": 1, - "explanation": "For voltage ratios use 20 log10(U2/U1); 20 log10(15) is about 23.5 dB.", - "source": "https://50ohm.de/A_dezibel_2.html", + "revision": 3, + "explanation": "For voltage ratios use 20 log10(U2/U1); 20 log10(15) is about 23.5 dB. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_dezibel_2.html#AA111", "confidence": 8 }, "AA112": { - "revision": 1, - "explanation": "120 dB relative to 1 microvolt per meter is a voltage ratio of 10^(120/20) = 10^6, so the field is 1 V/m.", - "source": "https://50ohm.de/A_dezibel_2.html", + "revision": 2, + "explanation": "120 dB relative to 1 microvolt per meter is a voltage ratio of 10^(120/20) = 10^6, so the field is 1 V/m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_dezibel_2.html#AA112", "confidence": 8 }, "AA113": { - "revision": 1, - "explanation": "Each S-step is 6 dB; S4 to S7 is three steps, so 3 x 6 dB = 18 dB.", - "source": "https://50ohm.de/NEA_s_meter.html", + "revision": 3, + "explanation": "Each S-step is 6 dB; S4 to S7 is three steps, so 3 x 6 dB = 18 dB. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_s_meter.html#AA113", "confidence": 8 }, "AA114": { - "revision": 1, - "explanation": "From S9+20 dB down to S9 removes 20 dB, and from S9 to S8 removes another 6 dB, totaling 26 dB.", - "source": "https://50ohm.de/NEA_s_meter.html", + "revision": 3, + "explanation": "From S9+20 dB down to S9 removes 20 dB, and from S9 to S8 removes another 6 dB, totaling 26 dB. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_s_meter.html#AA114", "confidence": 8 }, "AA115": { - "revision": 1, - "explanation": "1 ppm is one part in one million; 435 MHz divided by 10^6 is 435 Hz.", - "source": "https://50ohm.de/A_frequenzgenauigkeit.html", + "revision": 3, + "explanation": "1 ppm is one part in one million; 435 MHz divided by 10^6 is 435 Hz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzgenauigkeit.html#AA115", "confidence": 8 }, "AA116": { - "revision": 1, - "explanation": "10 ppm at 14.200000 MHz is 14.2 MHz x 10/10^6 = 142 Hz, so the possible frequency is 14.200000 MHz plus or minus 0.000142 MHz.", - "source": "https://50ohm.de/A_frequenzgenauigkeit.html", + "revision": 3, + "explanation": "10 ppm at 14.200000 MHz is 14.2 MHz x 10/10^6 = 142 Hz, so the possible frequency is 14.200000 MHz plus or minus 0.000142 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzgenauigkeit.html#AA116", "confidence": 8 }, "AB101": { - "revision": 1, + "revision": 2, "explanation": "Use $R = rho l/A$ with copper $rho = 0.018 ohm mm2/m$ and $A = pi(0.1 mm)^2 = 0.0314 mm2$; $0.018 x 1.8 / 0.0314$ is about 1.02 ohm.", - "source": "https://50ohm.de/EA_leiterwiderstand.html", + "source": "https://50ohm.de/NEA_leiterwiderstand.html#AB101", "confidence": 8 }, "AB102": { - "revision": 1, + "revision": 2, "explanation": "Rearrange $R = rho l/A$ to $l = RA/rho$; $1.5 ohm x 0.5 mm2 / 0.018 ohm mm2/m$ is about 41.7 m.", - "source": "https://50ohm.de/EA_leiterwiderstand.html", + "source": "https://50ohm.de/NEA_leiterwiderstand.html#AB102", "confidence": 8 }, "AB103": { - "revision": 1, + "revision": 2, "explanation": "In metals, higher temperature increases lattice vibration and electron scattering, so resistance normally rises with a positive temperature coefficient.", - "source": "https://50ohm.de/EA_leiterwiderstand.html", + "source": "https://50ohm.de/NEA_leiterwiderstand.html#AB103", "confidence": 8 }, "AB104": { - "revision": 1, + "revision": 2, "explanation": "Semiconductors such as silicon are poor conductors when pure, but heat or small amounts of dopant atoms can provide mobile charge carriers.", - "source": "https://50ohm.de/A_halbleiter_2.html", + "source": "https://50ohm.de/NEA_halbleiter_2.html#AB104", "confidence": 8 }, "AB105": { - "revision": 1, + "revision": 2, "explanation": "Doping means deliberately adding atoms with different valence to a semiconductor so extra electrons or holes become available as charge carriers.", - "source": "https://50ohm.de/A_halbleiter_2.html", + "source": "https://50ohm.de/NEA_halbleiter_2.html#AB105", "confidence": 8 }, "AB106": { - "revision": 1, + "revision": 2, "explanation": "N-type material is doped to have extra mobile electrons; electrons are the majority carriers.", - "source": "https://50ohm.de/A_halbleiter_2.html", + "source": "https://50ohm.de/NEA_halbleiter_2.html#AB106", "confidence": 8 }, "AB107": { - "revision": 1, + "revision": 2, "explanation": "P-type material is doped to create mobile holes; holes are the majority carriers.", - "source": "https://50ohm.de/A_halbleiter_2.html", + "source": "https://50ohm.de/NEA_halbleiter_2.html#AB107", "confidence": 8 }, "AB108": { - "revision": 1, + "revision": 2, "explanation": "At the PN junction, electrons diffuse from the N side and recombine with holes on the P side, leaving a depleted insulating region at the boundary.", - "source": "https://50ohm.de/A_halbleiter_2.html", + "source": "https://50ohm.de/NEA_halbleiter_2.html#AB108", "confidence": 7 }, "AB109": { - "revision": 1, + "revision": 2, "explanation": "The shown polarity reverse-biases the diode, pulling majority carriers away from the junction, so the depletion region widens.", - "source": "https://50ohm.de/NEA_halbleiter_2.html", + "source": "https://50ohm.de/NEA_halbleiter_2.html#AB109", "confidence": 7 }, "AB201": { - "revision": 1, + "revision": 2, "explanation": "A voltage source should hold voltage constant, which requires low internal resistance; a current source should hold current constant, which requires high internal resistance.", - "source": "https://50ohm.de/A_slide_a_strom_spannungsversorgung.html", + "source": "https://50ohm.de/NEA_innenwiderstand.html#AB201", "confidence": 8 }, "AB202": { - "revision": 1, - "explanation": "Maximum power transfer occurs when the load resistance equals the source internal resistance.", - "source": "https://50ohm.de/A_slide_a_strom_spannungsversorgung.html", + "revision": 2, + "explanation": "Maximum power transfer occurs when the load resistance equals the source internal resistance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_innenwiderstand.html#AB202", "confidence": 8 }, "AB203": { - "revision": 1, - "explanation": "Voltage matching minimizes voltage drop inside the source, so the load resistance must be much larger than the source internal resistance.", - "source": "https://50ohm.de/A_slide_a_strom_spannungsversorgung.html", + "revision": 2, + "explanation": "Voltage matching minimizes voltage drop inside the source, so the load resistance must be much larger than the source internal resistance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_innenwiderstand.html#AB203", "confidence": 8 }, "AB204": { - "revision": 1, - "explanation": "Current matching uses a source whose internal resistance is much larger than the load, so the load current stays nearly constant.", - "source": "https://50ohm.de/A_slide_a_strom_spannungsversorgung.html", + "revision": 2, + "explanation": "Current matching uses a source whose internal resistance is much larger than the load, so the load current stays nearly constant. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_innenwiderstand.html#AB204", "confidence": 8 }, "AB205": { - "revision": 1, + "revision": 2, "explanation": "The load current is $4.8 V / 1.2 ohm = 4 A$ and the source drops 0.2 V internally, so $R_i = 0.2 V / 4 A = 0.05 ohm$.", - "source": "https://50ohm.de/EA_innenwiderstand.html", + "source": "https://50ohm.de/NEA_innenwiderstand.html#AB205", "confidence": 8 }, "AB206": { - "revision": 1, + "revision": 2, "explanation": "The internal voltage drop is $13.5 V - 12.4 V = 1.1 V$; dividing by 0.9 A gives about 1.22 ohm.", - "source": "https://50ohm.de/EA_innenwiderstand.html", + "source": "https://50ohm.de/NEA_innenwiderstand.html#AB206", "confidence": 8 }, "AB207": { - "revision": 1, + "revision": 2, "explanation": "The terminal voltage falls by 0.5 V at 2 A, so $R_i = 0.5 V / 2 A = 0.25 ohm$.", - "source": "https://50ohm.de/EA_innenwiderstand.html", + "source": "https://50ohm.de/NEA_innenwiderstand.html#AB207", "confidence": 8 }, "AB208": { - "revision": 1, - "explanation": "The voltage drop is 0.2 V at 20 A, so $R_i = 0.2 V / 20 A = 0.01 ohm = 10 milliohm$.", - "source": "https://50ohm.de/EA_innenwiderstand.html", + "revision": 2, + "explanation": "The voltage drop is 0.2 V at 20 A, so $R_i = 0.2 V / 20 A = 0.01 ohm = 10 milliohm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_innenwiderstand.html#AB208", "confidence": 8 }, "AB209": { - "revision": 1, - "explanation": "The six 2 V cells are in series, so voltages add to 12 V while the ampere-hour capacity remains that of one cell, 10 Ah.", - "source": "https://50ohm.de/A_akku.html", + "revision": 3, + "explanation": "The six 2 V cells are in series, so voltages add to 12 V while the ampere-hour capacity remains that of one cell, 10 Ah. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_akku.html#AB209", "confidence": 7 }, "AB210": { - "revision": 1, + "revision": 2, "explanation": "The mAh value on an accumulator pack states how much charge it can nominally deliver, so it is the nominal capacity.", - "source": "https://50ohm.de/A_akku.html", + "source": "https://50ohm.de/NEA_akku.html#AB210", "confidence": 8 }, "AB211": { - "revision": 1, + "revision": 2, "explanation": "Discharging only down to 10 percent leaves 90 percent usable: $0.9 x 60 Ah = 54 Ah$; $54 Ah / 0.8 A = 67.5 h$.", - "source": "https://50ohm.de/A_akku.html", + "source": "https://50ohm.de/NEA_akku.html#AB211", "confidence": 8 }, "AB212": { - "revision": 1, + "revision": 2, "explanation": "A solar cell converts incident light or other radiation energy directly into electrical energy by freeing charge carriers.", - "source": "https://50ohm.de/EA_photovoltaik.html", + "source": "https://50ohm.de/NEA_photovoltaik.html#AB212", "confidence": 8 }, "AB213": { - "revision": 1, + "revision": 2, "explanation": "Input power is $12 V x 2 A = 24 W$ and output power is $5 V x 3 A = 15 W$; efficiency is $15/24 = 62.5%$.", - "source": "https://50ohm.de/NEA_spannungswandler.html", + "source": "https://50ohm.de/NEA_spannungswandler.html#AB213", "confidence": 8 }, "AB214": { - "revision": 1, + "revision": 2, "explanation": "Input power is $5 V x 3 A = 15 W$ and output power is $12 V x 1 A = 12 W$; efficiency is $12/15 = 80%$.", - "source": "https://50ohm.de/NEA_spannungswandler.html", + "source": "https://50ohm.de/NEA_spannungswandler.html#AB214", "confidence": 8 }, "AB301": { - "revision": 1, - "explanation": "For a sine current, $I_eff = I_max / sqrt(2)$; power is $I_eff^2 R = (0.5/sqrt(2))^2 x 20 = 2.5 W$.", - "source": "https://50ohm.de/EA_wechselstrom_leistung.html", + "revision": 2, + "explanation": "For a sine current, $I_eff = I_max / sqrt(2)$; power is $I_eff^2 R = (0.5/sqrt(2))^2 x 20 = 2.5 W$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wechselstrom_leistung.html#AB301", "confidence": 8 }, "AB302": { - "revision": 1, - "explanation": "Point X3 is three quarters of a cycle after zero, which is 270 degrees or $3 pi / 2$ radians.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "revision": 2, + "explanation": "Point X3 is three quarters of a cycle after zero, which is 270 degrees or $3 pi / 2$ radians. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_phase.html#AB302", "confidence": 7 }, "AB303": { - "revision": 1, + "revision": 2, "explanation": "The two sine waves are shifted by one eighth of a full cycle; $360 degrees / 8 = 45 degrees$.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "source": "https://50ohm.de/NEA_phase.html#AB303", "confidence": 7 }, "AB401": { - "revision": 2, + "revision": 3, "explanation": "Harmonics are integer multiples of a fundamental frequency: first harmonic is the fundamental, second is twice it, and so on.", - "source": "https://50ohm.de/A_slide_a_sender.html", + "source": "https://50ohm.de/NEA_nicht_sinus_signale.html#AB401", "confidence": 8 }, "AB402": { - "revision": 3, + "revision": 4, "explanation": "Overtones count only the harmonics above the fundamental: 1st overtone = 2nd harmonic, 2nd overtone = 3rd harmonic, 3rd overtone = 4th harmonic.", - "source": "https://50ohm.de/A_slide_a_sender.html", + "source": "https://50ohm.de/NEA_nicht_sinus_signale.html#AB402", "confidence": 8 }, "AB403": { - "revision": 2, + "revision": 3, "explanation": "A non-sinusoidal periodic waveform can be decomposed into its fundamental plus integer-multiple overtones.", - "source": "https://50ohm.de/A_slide_a_sender.html", + "source": "https://50ohm.de/NEA_nicht_sinus_signale.html#AB403", "confidence": 7 }, "AB404": { - "revision": 1, + "revision": 2, "explanation": "An ideal sine wave has only one spectral line at its fundamental frequency, so the matching spectrum contains a single component.", - "source": "https://50ohm.de/NEA_fourier_transformation.html", + "source": "https://50ohm.de/NEA_fourier_transformation.html#AB404", "confidence": 7 }, "AB405": { - "revision": 1, + "revision": 2, "explanation": "A non-sinusoidal periodic signal has a fundamental plus harmonic lines, so the matching spectrum shows multiple discrete components at integer multiples.", - "source": "https://50ohm.de/NEA_fourier_transformation.html", + "source": "https://50ohm.de/NEA_fourier_transformation.html#AB405", "confidence": 7 }, "AB406": { - "revision": 1, + "revision": 2, "explanation": "A spectrum with only one line corresponds to a pure sinusoidal time-domain signal.", - "source": "https://50ohm.de/NEA_fourier_transformation.html", + "source": "https://50ohm.de/NEA_fourier_transformation.html#AB406", "confidence": 7 }, "AB407": { - "revision": 1, + "revision": 2, "explanation": "The shown harmonic spectrum corresponds to the periodic non-sinusoidal waveform whose components line up with those harmonic amplitudes.", - "source": "https://50ohm.de/NEA_fourier_transformation.html", + "source": "https://50ohm.de/NEA_fourier_transformation.html#AB407", "confidence": 7 }, "AB408": { - "revision": 1, + "revision": 2, "explanation": "White noise has roughly constant power per hertz, so the total received noise power is proportional to receiver bandwidth.", - "source": "https://50ohm.de/A_rauschen.html", + "source": "https://50ohm.de/NEA_rauschen.html#AB408", "confidence": 8 }, "AB409": { - "revision": 1, + "revision": 2, "explanation": "Noise power scales with bandwidth; changing from 2.5 kHz to 0.5 kHz is a factor of 5 reduction, and 10 log10(5) is about 7 dB.", - "source": "https://50ohm.de/A_rauschen.html", + "source": "https://50ohm.de/NEA_rauschen.html#AB409", "confidence": 8 }, "AB501": { - "revision": 1, - "explanation": "Stored energy in watt-hours is voltage times ampere-hour capacity: $12 V x 5 Ah = 60 Wh$.", - "source": "https://50ohm.de/A_akku.html", + "revision": 3, + "explanation": "Stored energy in watt-hours is voltage times ampere-hour capacity: $12 V x 5 Ah = 60 Wh$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_akku.html#AB501", "confidence": 8 }, "AB502": { - "revision": 1, - "explanation": "Power is $230 V x 0.63 A = 144.9 W$; over 7 h this is $144.9 W x 7 h = 1014 Wh$, about 1.01 kWh.", - "source": "https://50ohm.de/EA_ladung_energie.html", + "revision": 3, + "explanation": "Power is $230 V x 0.63 A = 144.9 W$; over 7 h this is $144.9 W x 7 h = 1014 Wh$, about 1.01 kWh. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ladung_energie.html#AB502", "confidence": 8 }, "AB503": { - "revision": 1, - "explanation": "The resistor has $P = U^2/R = 10^2/100 = 1 W$; over one hour that is 1 Wh, equal to 3600 J.", - "source": "https://50ohm.de/EA_ladung_energie.html", + "revision": 3, + "explanation": "The resistor has $P = U^2/R = 10^2/100 = 1 W$; over one hour that is 1 Wh, equal to 3600 J. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ladung_energie.html#AB503", "confidence": 7 }, "AB601": { - "revision": 1, + "revision": 2, "explanation": "In metal conductors the physical current direction is the electron motion, from the negative pole toward the positive pole, opposite conventional current.", - "source": "https://50ohm.de/NEA_physikalische_stromrichtung.html", + "source": "https://50ohm.de/NEA_physikalische_stromrichtung.html#AB601", "confidence": 7 }, "AC101": { - "revision": 1, + "revision": 2, "explanation": "In an ideal capacitor the current is proportional to the rate of voltage change, so current reaches its extrema a quarter cycle before voltage: it leads by 90 degrees.", - "source": "https://50ohm.de/A_kondensator_2.html", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC101", "confidence": 8 }, "AC102": { - "revision": 1, + "revision": 2, "explanation": "Capacitive reactance is negative in AC sign convention, and its magnitude is $1/(2 pi f C)$, so it depends on frequency and capacitance.", - "source": "https://50ohm.de/NEA_kondensator_2.html", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC102", "confidence": 8 }, "AC103": { - "revision": 1, + "revision": 2, "explanation": "A pure reactance stores and returns energy instead of converting it to heat, so the ideal reactive resistance has no heat loss.", - "source": "https://50ohm.de/A_kondensator_2.html", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC103", "confidence": 8 }, "AC104": { - "revision": 1, + "revision": 2, "explanation": "Use $X_C = 1/(2 pi f C)$; with 100 MHz and 10 pF this gives about 159 ohm.", - "source": "https://50ohm.de/NEA_kondensator_2.html", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC104", "confidence": 8 }, "AC105": { - "revision": 1, + "revision": 2, "explanation": "Use $X_C = 1/(2 pi f C)$; with 145 MHz and 50 pF this is about 22 ohm.", - "source": "https://50ohm.de/NEA_kondensator_2.html", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC105", "confidence": 8 }, "AC106": { - "revision": 1, + "revision": 2, "explanation": "Use $X_C = 1/(2 pi f C)$; with 100 MHz and 100 pF this gives about 15.9 ohm.", - "source": "https://50ohm.de/NEA_kondensator_2.html", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC106", "confidence": 8 }, "AC107": { - "revision": 1, + "revision": 2, "explanation": "Use $X_C = 1/(2 pi f C)$; with 435 MHz and 100 pF this gives about 3.7 ohm.", - "source": "https://50ohm.de/NEA_kondensator_2.html", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC107", "confidence": 8 }, "AC108": { - "revision": 1, - "explanation": "First find reactance from $X_C = U/I = 16 V / 0.032 A = 500 ohm$; then $C = 1/(2 pi f X_C)$ gives about 6.37 microfarad.", - "source": "https://50ohm.de/NEA_kondensator_2.html", + "revision": 3, + "explanation": "First find reactance from $X_C = U/I = 16 V / 0.032 A = 500 ohm$; then $C = 1/(2 pi f X_C)$ gives about 6.37 microfarad. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC108", "confidence": 8 }, "AC109": { - "revision": 1, + "revision": 2, "explanation": "Real capacitors are not ideal: dielectric loss and lead or ESR losses convert some energy into heat under AC operation.", - "source": "https://50ohm.de/EA_kondensator_2.html", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC109", "confidence": 8 }, "AC110": { - "revision": 1, - "explanation": "Capacitor loss is commonly described by loss factor tan delta; high loss means low quality factor, with tan delta equal to the reciprocal of Q.", - "source": "https://50ohm.de/EA_kondensator_2.html", + "revision": 2, + "explanation": "Capacitor loss is commonly described by loss factor tan delta; high loss means low quality factor, with tan delta equal to the reciprocal of Q. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC110", "confidence": 8 }, "AC111": { - "revision": 1, - "explanation": "An ideal capacitor draws reactive current but no real power in steady-state AC, so the real power is approximately zero.", - "source": "https://50ohm.de/A_kondensator_2.html", + "revision": 2, + "explanation": "An ideal capacitor draws reactive current but no real power in steady-state AC, so the real power is approximately zero. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kondensator_2.html#AC111", "confidence": 8 }, "AC201": { - "revision": 1, + "revision": 2, "explanation": "In an ideal inductor the magnetic field opposes current changes, so current lags the applied voltage by 90 degrees.", - "source": "https://50ohm.de/A_spule_2.html", + "source": "https://50ohm.de/NEA_spule_2.html#AC201", "confidence": 8 }, "AC202": { - "revision": 1, + "revision": 2, "explanation": "Inductive reactance is positive in AC sign convention and has magnitude $X_L = 2 pi f L$, so it depends on frequency and inductance.", - "source": "https://50ohm.de/A_spule_2.html", + "source": "https://50ohm.de/NEA_spule_2.html#AC202", "confidence": 8 }, "AC203": { - "revision": 1, - "explanation": "With DC only the winding resistance limits current; with AC the inductive reactance is added, so the total impedance is higher and current is smaller.", - "source": "https://50ohm.de/A_spule_2.html", + "revision": 2, + "explanation": "With DC only the winding resistance limits current; with AC the inductive reactance is added, so the total impedance is higher and current is smaller. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spule_2.html#AC203", "confidence": 8 }, "AC204": { - "revision": 1, + "revision": 2, "explanation": "Use $X_L = 2 pi f L$; $2 pi x 100 MHz x 3 microhenry$ is about 1885 ohm.", - "source": "https://50ohm.de/A_spule_2.html", + "source": "https://50ohm.de/NEA_spule_2.html#AC204", "confidence": 8 }, "AC205": { - "revision": 1, - "explanation": "For a core with AL value, $L = N^2 x AL$; $14^2 x 1.5 nH = 294 nH = 0.294 microhenry$.", - "source": "https://50ohm.de/A_spule_2.html", + "revision": 2, + "explanation": "For a core with AL value, $L = N^2 x AL$; $14^2 x 1.5 nH = 294 nH = 0.294 microhenry$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spule_2.html#AC205", "confidence": 8 }, "AC206": { - "revision": 1, - "explanation": "Use $L = N^2 x AL$; $300^2 x 1250 nH = 112500000 nH = 112.5 mH$.", - "source": "https://50ohm.de/A_spule_2.html", + "revision": 2, + "explanation": "Use $L = N^2 x AL$; $300^2 x 1250 nH = 112500000 nH = 112.5 mH$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spule_2.html#AC206", "confidence": 8 }, "AC207": { - "revision": 1, - "explanation": "Rearrange to $N = sqrt(L/AL)$; $sqrt(2 mH / 250 nH) = sqrt(8000)$, about 89 turns.", - "source": "https://50ohm.de/A_spule_2.html", + "revision": 2, + "explanation": "Rearrange to $N = sqrt(L/AL)$; $sqrt(2 mH / 250 nH) = sqrt(8000)$, about 89 turns. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spule_2.html#AC207", "confidence": 8 }, "AC208": { - "revision": 1, - "explanation": "Rearrange to $N = sqrt(L/AL)$; $sqrt(12 microhenry / 30 nH) = sqrt(400) = 20 turns$.", - "source": "https://50ohm.de/A_spule_2.html", + "revision": 2, + "explanation": "Rearrange to $N = sqrt(L/AL)$; $sqrt(12 microhenry / 30 nH) = sqrt(400) = 20 turns$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spule_2.html#AC208", "confidence": 8 }, "AC209": { - "revision": 1, - "explanation": "Coil losses are represented by an equivalent series resistance; the loss factor tan delta is used and equals the reciprocal of the quality factor Q.", - "source": "https://50ohm.de/A_spule_2.html", + "revision": 2, + "explanation": "Coil losses are represented by an equivalent series resistance; the loss factor tan delta is used and equals the reciprocal of the quality factor Q. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spule_2.html#AC209", "confidence": 8 }, "AC210": { - "revision": 1, + "revision": 2, "explanation": "A conductive metal enclosure shields the electric field around the tuned-circuit coil and reduces unwanted radiation from it.", - "source": "https://50ohm.de/A_spule_2.html", + "source": "https://50ohm.de/NEA_spule_2.html#AC210", "confidence": 8 }, "AC211": { - "revision": 1, + "revision": 2, "explanation": "A choke core is normally ferrite because ferrite gives high magnetic permeability and high RF loss for unwanted common-mode currents.", - "source": "https://50ohm.de/A_spule_2.html", + "source": "https://50ohm.de/NEA_spule_2.html#AC211", "confidence": 7 }, "AC301": { - "revision": 1, + "revision": 2, "explanation": "Mutual induction needs a changing magnetic field, so a changing current in a magnetically coupled neighboring coil induces voltage in the other coil.", - "source": "https://50ohm.de/A_uebertrager_2.html", + "source": "https://50ohm.de/NEA_uebertrager_2.html#AC301", "confidence": 8 }, "AC302": { - "revision": 1, - "explanation": "With losses neglected, primary and secondary power are equal: $6 V x 1.15 A = 6.9 W$, and $6.9 W / 230 V = 0.030 A$.", - "source": "https://50ohm.de/A_uebertrager_2.html", + "revision": 3, + "explanation": "With losses neglected, primary and secondary power are equal: $6 V x 1.15 A = 6.9 W$, and $6.9 W / 230 V = 0.030 A$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_uebertrager_2.html#AC302", "confidence": 8 }, "AC303": { - "revision": 1, - "explanation": "Impedance transforms with the square of the turns ratio; with 1:4, the input sees $16 kOhm / 4^2 = 1 kOhm$.", - "source": "https://50ohm.de/A_uebertrager_2.html", + "revision": 2, + "explanation": "Impedance transforms with the square of the turns ratio; with 1:4, the input sees $16 kOhm / 4^2 = 1 kOhm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_uebertrager_2.html#AC303", "confidence": 7 }, "AC304": { - "revision": 1, - "explanation": "The same 1:4 transformer reflects the secondary load by a factor of 16, so $6.4 kOhm / 16 = 0.4 kOhm$ at a-b.", - "source": "https://50ohm.de/A_uebertrager_2.html", + "revision": 2, + "explanation": "The same 1:4 transformer reflects the secondary load by a factor of 16, so $6.4 kOhm / 16 = 0.4 kOhm$ at a-b. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_uebertrager_2.html#AC304", "confidence": 7 }, "AC305": { - "revision": 1, + "revision": 2, "explanation": "The impedance ratio is $450/50 = 9$; turns ratio is the square root of impedance ratio, so $sqrt(9) = 3$.", - "source": "https://50ohm.de/A_uebertrager_2.html", + "source": "https://50ohm.de/NEA_uebertrager_2.html#AC305", "confidence": 8 }, "AC306": { - "revision": 1, + "revision": 2, "explanation": "A 2.5 kOhm load against 50 ohm is about a 50:1 impedance ratio, close to 49:1, so the turns ratio is about 1:7.", - "source": "https://50ohm.de/A_uebertrager_2.html", + "source": "https://50ohm.de/NEA_uebertrager_2.html#AC306", "confidence": 8 }, "AC307": { - "revision": 1, - "explanation": "The wire area is $pi d^2/4 = pi x 0.5^2/4 = 0.196 mm2$; at 2.5 A/mm2 the current is about 0.49 A.", - "source": "https://50ohm.de/A_uebertrager_2.html", + "revision": 3, + "explanation": "The wire area is $pi d^2/4 = pi x 0.5^2/4 = 0.196 mm2$; at 2.5 A/mm2 the current is about 0.49 A. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_uebertrager_2.html#AC307", "confidence": 8 }, "AC401": { - "revision": 1, + "revision": 2, "explanation": "In forward bias, the depletion region is reduced and electrons can cross the PN junction from the N side to the P side.", - "source": "https://50ohm.de/A_diode_2.html", + "source": "https://50ohm.de/NEA_diode_2.html#AC401", "confidence": 8 }, "AC402": { - "revision": 1, + "revision": 2, "explanation": "Electrons are the majority carriers in the N region, and in forward operation they move across the junction into the P region.", - "source": "https://50ohm.de/A_diode_2.html", + "source": "https://50ohm.de/NEA_halbleiter_2.html#AC402", "confidence": 8 }, "AC403": { - "revision": 1, + "revision": 2, "explanation": "As temperature rises, diode saturation current increases, so the forward voltage needed for a given current falls.", - "source": "https://50ohm.de/A_diode_2.html", + "source": "https://50ohm.de/NEA_diode_2.html#AC403", "confidence": 8 }, "AC404": { - "revision": 1, + "revision": 2, "explanation": "A varicap is reverse-biased; lower reverse voltage makes the depletion region narrower, which increases junction capacitance.", - "source": "https://50ohm.de/A_diode_2.html", + "source": "https://50ohm.de/NEA_diode_2.html#AC404", "confidence": 8 }, "AC405": { - "revision": 1, - "explanation": "Antiparallel silicon diodes clip the waveform when either polarity exceeds about 0.6 V, so the output is the sine wave limited at that threshold.", - "source": "https://50ohm.de/A_diode_2.html", + "revision": 2, + "explanation": "Antiparallel silicon diodes clip the waveform when either polarity exceeds about 0.6 V, so the output is the sine wave limited at that threshold. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_diode_2.html#AC405", "confidence": 7 }, "AC406": { - "revision": 1, - "explanation": "Germanium diodes have a lower threshold, about 0.3 V, so the same limiter clips the waveform earlier and more strongly than silicon diodes.", - "source": "https://50ohm.de/A_diode_2.html", + "revision": 2, + "explanation": "Germanium diodes have a lower threshold, about 0.3 V, so the same limiter clips the waveform earlier and more strongly than silicon diodes. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_diode_2.html#AC406", "confidence": 7 }, "AC407": { - "revision": 1, + "revision": 2, "explanation": "A photodiode generates electron-hole pairs when illuminated and can produce photocurrent from light.", - "source": "https://50ohm.de/A_diode_2.html", + "source": "https://50ohm.de/NEA_diode_2.html#AC407", "confidence": 8 }, "AC408": { - "revision": 1, + "revision": 2, "explanation": "An optocoupler transfers a signal optically between an LED and a photosensitive device, giving galvanic isolation between the two circuits.", - "source": "https://50ohm.de/A_diode_2.html", + "source": "https://50ohm.de/NEA_diode_2.html#AC408", "confidence": 8 }, "AC501": { - "revision": 1, + "revision": 2, "explanation": "In a bipolar transistor, a small base current controls a larger collector current, so it is current-controlled.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC501", "confidence": 8 }, "AC502": { - "revision": 1, + "revision": 2, "explanation": "A field-effect transistor controls channel current by the electric field from the gate-source voltage, so it is voltage-controlled.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC502", "confidence": 8 }, "AC503": { - "revision": 1, + "revision": 2, "explanation": "An NPN transistor has an N emitter, P base, and N collector, so the p-doped region is the base.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC503", "confidence": 8 }, "AC504": { - "revision": 1, + "revision": 2, "explanation": "A PNP transistor has a P emitter, N base, and P collector, so the n-doped region is the base.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC504", "confidence": 8 }, "AC505": { - "revision": 1, + "revision": 2, "explanation": "For a bipolar transistor to conduct normally, the base-emitter junction is forward biased.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC505", "confidence": 8 }, "AC506": { - "revision": 1, + "revision": 2, "explanation": "The symbol shows a gate controlling a channel between source and drain, which identifies a field-effect transistor.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC506", "confidence": 7 }, "AC507": { - "revision": 1, + "revision": 2, "explanation": "The continuous channel marks depletion-mode, self-conducting JFETs; the arrow direction distinguishes N-channel from P-channel in the two symbols.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC507", "confidence": 7 }, "AC508": { - "revision": 1, + "revision": 2, "explanation": "The insulated gate identifies a MOSFET, the interrupted channel marks enhancement mode, and the arrow/channel orientation identifies an N-channel device.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC508", "confidence": 7 }, "AC509": { - "revision": 1, + "revision": 2, "explanation": "The correct symbol combines an insulated gate, interrupted enhancement-mode channel, and N-channel arrow orientation.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC509", "confidence": 7 }, "AC510": { - "revision": 1, + "revision": 2, "explanation": "A depletion-mode N-channel MOSFET is recognized by the insulated gate plus continuous channel and N-channel arrow orientation.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC510", "confidence": 7 }, "AC511": { - "revision": 1, + "revision": 2, "explanation": "A depletion-mode P-channel MOSFET has the insulated gate, continuous channel, and the P-channel arrow orientation.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC511", "confidence": 7 }, "AC512": { - "revision": 1, + "revision": 2, "explanation": "FET terminals are named drain, gate, and source; emitter, base, and collector are bipolar-transistor names.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC512", "confidence": 8 }, "AC513": { - "revision": 1, + "revision": 2, "explanation": "The shown FET package labels the channel terminals as drain and source, with the control terminal as gate.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC513", "confidence": 7 }, "AC514": { - "revision": 1, + "revision": 2, "explanation": "The gate-source voltage changes the channel resistance between source and drain, thereby controlling drain current with almost no gate current.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC514", "confidence": 8 }, "AC515": { - "revision": 1, - "explanation": "Base current is $5 mA / 298 = 16.8 microampere$; with about 0.6 V base-emitter drop, $R_1 = (12 - 0.6) V / 16.8 microampere$, about 680 kOhm.", - "source": "https://50ohm.de/A_transistor_2.html", + "revision": 2, + "explanation": "Base current is $5 mA / 298 = 16.8 microampere$; with about 0.6 V base-emitter drop, $R_1 = (12 - 0.6) V / 16.8 microampere$, about 680 kOhm. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transistor_2.html#AC515", "confidence": 7 }, "AC516": { - "revision": 1, - "explanation": "Making the divider current much larger than base current keeps the base voltage mostly set by the divider, so transistor beta and temperature changes disturb the operating point less.", - "source": "https://50ohm.de/A_transistor_2.html", + "revision": 2, + "explanation": "Making the divider current much larger than base current keeps the base voltage mostly set by the divider, so transistor beta and temperature changes disturb the operating point less. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transistor_2.html#AC516", "confidence": 7 }, "AC517": { - "revision": 1, - "explanation": "Base current is $2 mA/200 = 10 microampere$; R2 carries ten times that, so R1 carries 110 microampere. With 1 V at the emitter, the base is about 1.6 V, giving $R_1 = 8.4 V/110 microampere = 76.4 kOhm$.", - "source": "https://50ohm.de/A_transistor_2.html", + "revision": 2, + "explanation": "Base current is $2 mA/200 = 10 microampere$; R2 carries ten times that, so R1 carries 110 microampere. With 1 V at the emitter, the base is about 1.6 V, giving $R_1 = 8.4 V/110 microampere = 76.4 kOhm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transistor_2.html#AC517", "confidence": 7 }, "AC518": { - "revision": 1, - "explanation": "Base current is 10 microampere and R2 current is 100 microampere, so R1 current is 110 microampere; with the base near 0.6 V, $R_1 = 9.4 V/110 microampere = 85.5 kOhm$.", - "source": "https://50ohm.de/A_transistor_2.html", + "revision": 2, + "explanation": "Base current is 10 microampere and R2 current is 100 microampere, so R1 current is 110 microampere; with the base near 0.6 V, $R_1 = 9.4 V/110 microampere = 85.5 kOhm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transistor_2.html#AC518", "confidence": 7 }, "AC519": { - "revision": 1, - "explanation": "If R1 is open, the base receives no forward bias, the transistor switches off, and with no collector current the collector rises to the supply voltage.", - "source": "https://50ohm.de/A_transistor_2.html", + "revision": 2, + "explanation": "If R1 is open, the base receives no forward bias, the transistor switches off, and with no collector current the collector rises to the supply voltage. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transistor_2.html#AC519", "confidence": 7 }, "AC520": { - "revision": 1, - "explanation": "If R2 is open, the base is driven too strongly through R1, so the transistor saturates; collector current is then limited mainly by RC and collector voltage falls near saturation voltage.", - "source": "https://50ohm.de/A_transistor_2.html", + "revision": 2, + "explanation": "If R2 is open, the base is driven too strongly through R1, so the transistor saturates; collector current is then limited mainly by RC and collector voltage falls near saturation voltage. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transistor_2.html#AC520", "confidence": 7 }, "AC521": { - "revision": 1, - "explanation": "The gate draws negligible current, so the divider gives $U_G = 44 V x 1 kOhm/(10 kOhm + 1 kOhm) = 4 V$; with the source at reference, that is $U_GS$.", - "source": "https://50ohm.de/A_transistor_2.html", + "revision": 2, + "explanation": "The gate draws negligible current, so the divider gives $U_G = 44 V x 1 kOhm/(10 kOhm + 1 kOhm) = 4 V$; with the source at reference, that is $U_GS$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transistor_2.html#AC521", "confidence": 7 }, "AC522": { - "revision": 1, - "explanation": "For a divider, $R_2 = R_1 U_G/(U_B - U_G)$; $10 kOhm x 2.8/(44 - 2.8)$ gives about 680 ohm.", - "source": "https://50ohm.de/A_transistor_2.html", + "revision": 2, + "explanation": "For a divider, $R_2 = R_1 U_G/(U_B - U_G)$; $10 kOhm x 2.8/(44 - 2.8)$ gives about 680 ohm. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transistor_2.html#AC522", "confidence": 7 }, "AC523": { - "revision": 1, - "explanation": "Conduction loss is $P = I^2 R$; $25^2 x 0.004 ohm = 2.5 W$.", - "source": "https://50ohm.de/A_transistor_2.html", + "revision": 2, + "explanation": "Conduction loss is $P = I^2 R$; $25^2 x 0.004 ohm = 2.5 W$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transistor_2.html#AC523", "confidence": 8 }, "AC524": { - "revision": 2, + "revision": 3, "explanation": "When the switch opens, the inductor tries to maintain its current and reverses the voltage across itself. The flyback diode is wired antiparallel so it forward-conducts at that moment, providing a safe current path and clamping the back-EMF that would otherwise destroy the switching transistor.", - "source": "https://50ohm.de/A_transistor_2.html", + "source": "https://50ohm.de/NEA_transistor_2.html#AC524", "confidence": 7 }, "AC601": { - "revision": 2, + "revision": 3, "explanation": "An integrated circuit combines many circuit elements directly on one semiconductor substrate.", - "source": "https://50ohm.de/A_integrierte_schaltkreise.html", + "source": "https://50ohm.de/NEA_integrierte_schaltkreise.html#AC601", "confidence": 8 }, "AC602": { - "revision": 2, + "revision": 3, "explanation": "An MMIC is monolithic, so active and passive microwave circuit elements are integrated on the same semiconductor substrate.", - "source": "https://50ohm.de/A_integrierte_schaltkreise.html", + "source": "https://50ohm.de/NEA_integrierte_schaltkreise.html#AC602", "confidence": 8 }, "AC603": { - "revision": 2, + "revision": 3, "explanation": "An MMIC amplifier integrates the active device and matching elements, giving broad bandwidth and useful gain with fewer external components.", - "source": "https://50ohm.de/A_integrierte_schaltkreise.html", + "source": "https://50ohm.de/NEA_integrierte_schaltkreise.html#AC603", "confidence": 8 }, "AC604": { - "revision": 2, + "revision": 3, "explanation": "Many MMICs are designed as RF building blocks with standard input and output impedances such as 50 ohm.", - "source": "https://50ohm.de/A_integrierte_schaltkreise.html", + "source": "https://50ohm.de/NEA_integrierte_schaltkreise.html#AC604", "confidence": 8 }, "AD101": { - "revision": 1, - "explanation": "Series capacitors add by reciprocals: $1/C = 1/100 pF + 1/47 pF + 1/22 pF$, giving about 13.0 pF.", - "source": "https://50ohm.de/A_reihe_parallel_gemischt.html", + "revision": 2, + "explanation": "Series capacitors add by reciprocals: $1/C = 1/100 pF + 1/47 pF + 1/22 pF$, giving about 13.0 pF. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_gemischt.html#AD101", "confidence": 8 }, "AD102": { - "revision": 1, - "explanation": "Series inductances add directly: 2200 nH is 2.2 microhenry, 0.033 mH is 33 microhenry, so the sum is 2.2 + 33 + 150 = 185.2 microhenry.", - "source": "https://50ohm.de/A_reihe_parallel_gemischt.html", + "revision": 3, + "explanation": "Series inductances add directly: 2200 nH is 2.2 microhenry, 0.033 mH is 33 microhenry, so the sum is 2.2 + 33 + 150 = 185.2 microhenry. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihenschaltung_spule.html#AD102", "confidence": 8 }, "AD103": { - "revision": 1, - "explanation": "The shown capacitances are effectively parallel, so they add: 100 pF + 1500 pF + 220 pF + 1 pF = 1821 pF.", - "source": "https://50ohm.de/A_reihe_parallel_gemischt.html", + "revision": 2, + "explanation": "The shown capacitances are effectively parallel, so they add: 100 pF + 1500 pF + 220 pF + 1 pF = 1821 pF. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_gemischt.html#AD103", "confidence": 7 }, "AD104": { - "revision": 1, - "explanation": "At 1 MHz and 1 nF, $X_C$ is about 159 ohm; the series impedance magnitude is $sqrt(100^2 + 159^2)$, about 188 ohm.", - "source": "https://50ohm.de/A_reihe_parallel_gemischt.html", + "revision": 2, + "explanation": "At 1 MHz and 1 nF, $X_C$ is about 159 ohm; the series impedance magnitude is $sqrt(100^2 + 159^2)$, about 188 ohm. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_gemischt.html#AD104", "confidence": 8 }, "AD105": { - "revision": 1, - "explanation": "At 1 MHz and 100 microhenry, $X_L$ is about 628 ohm; $|Z| = sqrt(100^2 + 628^2)$, about 636 ohm.", - "source": "https://50ohm.de/A_reihe_parallel_gemischt.html", + "revision": 2, + "explanation": "At 1 MHz and 100 microhenry, $X_L$ is about 628 ohm; $|Z| = sqrt(100^2 + 628^2)$, about 636 ohm. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_gemischt.html#AD105", "confidence": 8 }, "AD106": { - "revision": 1, - "explanation": "If 1 mA flows through R3, the parallel section has 10 V across it; R2 draws another 1 mA, so 2 mA through R1 drops 20 V, making the total 30 V.", - "source": "https://50ohm.de/EA_reihe_parallel_widerstandsnetz_2.html", + "revision": 2, + "explanation": "If 1 mA flows through R3, the parallel section has 10 V across it; R2 draws another 1 mA, so 2 mA through R1 drops 20 V, making the total 30 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstandsnetz_2.html#AD106", "confidence": 7 }, "AD107": { - "revision": 1, - "explanation": "R2 and R3 in parallel give 5 kOhm, in series with R1 gives 15 kOhm; 15 V / 15 kOhm is 1 mA total, split equally so R3 has 0.5 mA.", - "source": "https://50ohm.de/EA_reihe_parallel_widerstandsnetz_2.html", + "revision": 2, + "explanation": "R2 and R3 in parallel give 5 kOhm, in series with R1 gives 15 kOhm; 15 V / 15 kOhm is 1 mA total, split equally so R3 has 0.5 mA. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstandsnetz_2.html#AD107", "confidence": 7 }, "AD108": { - "revision": 1, - "explanation": "The total current is 1 mA, so the parallel section has 5 V across it; R2 power is $5^2/10000 = 0.0025 W = 2.5 mW$.", - "source": "https://50ohm.de/EA_reihe_parallel_widerstandsnetz_2.html", + "revision": 2, + "explanation": "The total current is 1 mA, so the parallel section has 5 V across it; R2 power is $5^2/10000 = 0.0025 W = 2.5 mW$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstandsnetz_2.html#AD108", "confidence": 7 }, "AD109": { - "revision": 1, - "explanation": "The input is 200 ohm plus 100 ohm in parallel with 200 ohm + R; at R = 0 this is about 267 ohm, and at R = 1 kOhm it is about 292 ohm.", - "source": "https://50ohm.de/NEA_slide_nea_reihen_parallelschaltung.html", + "revision": 2, + "explanation": "The input is 200 ohm plus 100 ohm in parallel with 200 ohm + R; at R = 0 this is about 267 ohm, and at R = 1 kOhm it is about 292 ohm. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstandsnetz_2.html#AD109", "confidence": 7 }, "AD110": { - "revision": 1, - "explanation": "Each side branch is 2.2 kOhm + 220 ohm = 2420 ohm, and two equal branches in parallel give half that value, 1210 ohm.", - "source": "https://50ohm.de/NEA_slide_nea_reihen_parallelschaltung.html", + "revision": 2, + "explanation": "Each side branch is 2.2 kOhm + 220 ohm = 2420 ohm, and two equal branches in parallel give half that value, 1210 ohm. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstandsnetz_2.html#AD110", "confidence": 7 }, "AD111": { - "revision": 1, - "explanation": "A bridge has zero branch voltage when the two divider ratios are equal, which gives $R1/R2 = R3/R4$.", - "source": "https://50ohm.de/EA_brueckenschaltung.html", + "revision": 2, + "explanation": "A bridge has zero branch voltage when the two divider ratios are equal, which gives $R1/R2 = R3/R4$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_brueckenschaltung.html#AD111", "confidence": 7 }, "AD112": { - "revision": 1, - "explanation": "All four resistors are equal, so the two divider midpoints sit at the same potential; the bridge voltage from A to B is 0 V.", - "source": "https://50ohm.de/EA_brueckenschaltung.html", + "revision": 3, + "explanation": "All four resistors are equal, so the two divider midpoints sit at the same potential; the bridge voltage from A to B is 0 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_brueckenschaltung.html#AD112", "confidence": 7 }, "AD113": { - "revision": 1, - "explanation": "The left divider gives point A at 10 V and the right divider gives point B at 1 V, so measured from A to B the bridge voltage is +9 V.", - "source": "https://50ohm.de/EA_brueckenschaltung.html", + "revision": 2, + "explanation": "The left divider gives point A at 10 V and the right divider gives point B at 1 V, so measured from A to B the bridge voltage is +9 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_brueckenschaltung.html#AD113", "confidence": 7 }, "AD114": { - "revision": 1, - "explanation": "The load is parallel to R2: $2.2 kOhm || 8.2 kOhm$ is about 1.73 kOhm. The divider output is $12 V x 1.73/(10 + 1.73)$, about 1.8 V.", - "source": "https://50ohm.de/A_spannungsteiler_2.html", + "revision": 2, + "explanation": "The load is parallel to R2: $2.2 kOhm || 8.2 kOhm$ is about 1.73 kOhm. The divider output is $12 V x 1.73/(10 + 1.73)$, about 1.8 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsteiler_2.html#AD114", "confidence": 7 }, "AD115": { - "revision": 1, - "explanation": "Adding the load lowers the effective lower resistance of the divider, increasing the supply current through R1; with higher current, R1 dissipates more heat.", - "source": "https://50ohm.de/A_spannungsteiler_2.html", + "revision": 2, + "explanation": "Adding the load lowers the effective lower resistance of the divider, increasing the supply current through R1; with higher current, R1 dissipates more heat. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsteiler_2.html#AD115", "confidence": 7 }, "AD201": { - "revision": 1, - "explanation": "An RC high-pass cutoff is $f_g = 1/(2 pi R C)$; with 4.7 kOhm and 2.2 nF this is about 15.4 kHz.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 3, + "explanation": "An RC high-pass cutoff is $f_g = 1/(2 pi R C)$; with 4.7 kOhm and 2.2 nF this is about 15.4 kHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD201", "confidence": 7 }, "AD202": { - "revision": 1, - "explanation": "An RC low-pass has the same cutoff formula, $f_g = 1/(2 pi R C)$; with 10 kOhm and 47 nF this is about 339 Hz.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 3, + "explanation": "An RC low-pass has the same cutoff formula, $f_g = 1/(2 pi R C)$; with 10 kOhm and 47 nF this is about 339 Hz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD202", "confidence": 7 }, "AD203": { - "revision": 1, - "explanation": "The relevant low-pass is R1 with C1; C2 is supply decoupling and the amplifier input is very high impedance. $1/(2 pi x 4.7 kOhm x 6.8 nF)$ is about 5 kHz.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "The relevant low-pass is R1 with C1; C2 is supply decoupling and the amplifier input is very high impedance. $1/(2 pi x 4.7 kOhm x 6.8 nF)$ is about 5 kHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD203", "confidence": 7 }, "AD204": { - "revision": 1, + "revision": 2, "explanation": "A series resonant circuit has minimum impedance at resonance, while a parallel resonant circuit has maximum impedance there; the correct pairings match those curve shapes.", - "source": "https://50ohm.de/A_slide_a_grundlegende_schaltungen.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD204", "confidence": 7 }, "AD205": { - "revision": 1, + "revision": 2, "explanation": "The circuit passes only a middle range of frequencies while attenuating frequencies below and above that range, which is the behavior of a band-pass filter.", - "source": "https://50ohm.de/A_slide_a_grundlegende_schaltungen.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD205", "confidence": 7 }, "AD206": { - "revision": 1, + "revision": 2, "explanation": "At resonance, inductive and capacitive reactances have equal magnitude and opposite sign, so their reactive effects cancel.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD206", "confidence": 8 }, "AD207": { - "revision": 1, - "explanation": "In a series resonant circuit the L and C reactances cancel, leaving only the real series resistance R as the impedance.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "In a series resonant circuit the L and C reactances cancel, leaving only the real series resistance R as the impedance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD207", "confidence": 7 }, "AD208": { - "revision": 1, - "explanation": "Use Thomson's formula $f = 1/(2 pi sqrt(L C))$; with 1.2 microhenry and 6.8 pF the result is about 55.7 MHz.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "Use Thomson's formula $f = 1/(2 pi sqrt(L C))$; with 1.2 microhenry and 6.8 pF the result is about 55.7 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD208", "confidence": 7 }, "AD209": { - "revision": 1, - "explanation": "The resistor does not set the ideal resonant frequency; $1/(2 pi sqrt(10 microhenry x 1 nF))$ is about 1.592 MHz.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "The resistor does not set the ideal resonant frequency; $1/(2 pi sqrt(10 microhenry x 1 nF))$ is about 1.592 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD209", "confidence": 7 }, "AD210": { - "revision": 1, - "explanation": "Using $f = 1/(2 pi sqrt(L C))$ with 100 microhenry and 0.01 microfarad gives about 159 kHz.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "Using $f = 1/(2 pi sqrt(L C))$ with 100 microhenry and 0.01 microfarad gives about 159 kHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD210", "confidence": 7 }, "AD211": { - "revision": 1, - "explanation": "For the parallel resonant circuit, $f = 1/(2 pi sqrt(2.2 microhenry x 56 pF))$, giving about 14.34 MHz.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "For the parallel resonant circuit, $f = 1/(2 pi sqrt(2.2 microhenry x 56 pF))$, giving about 14.34 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD211", "confidence": 7 }, "AD212": { - "revision": 1, - "explanation": "The parallel capacitances add to about 1.82 nF; with 1.2 mH, $1/(2 pi sqrt(L C))$ gives about 107.7 kHz.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "The parallel capacitances add to about 1.82 nF; with 1.2 mH, $1/(2 pi sqrt(L C))$ gives about 107.7 kHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD212", "confidence": 7 }, "AD213": { - "revision": 1, + "revision": 2, "explanation": "Resonant frequency is inversely proportional to $sqrt(L C)$, so using a smaller inductance raises the frequency.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD213", "confidence": 8 }, "AD214": { - "revision": 1, + "revision": 2, "explanation": "Fewer turns reduce coil inductance, and lower inductance increases the resonant frequency.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD214", "confidence": 8 }, "AD215": { - "revision": 1, + "revision": 2, "explanation": "Increasing capacitance increases the LC product, so the resonant frequency decreases.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD215", "confidence": 8 }, "AD216": { - "revision": 1, + "revision": 2, "explanation": "Pushing the coil turns closer together increases inductance, and higher inductance lowers the resonant frequency.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD216", "confidence": 8 }, "AD217": { - "revision": 1, + "revision": 2, "explanation": "A ferrite core increases coil inductance, and the larger L in the LC formula lowers the resonant frequency.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD217", "confidence": 8 }, "AD218": { - "revision": 1, + "revision": 2, "explanation": "Moving the potentiometer toward X raises the reverse voltage on the varicap; higher reverse voltage lowers its capacitance, so the LC resonant frequency rises.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "source": "https://50ohm.de/NEA_oszillator_vco.html#AD218", "confidence": 7 }, "AD219": { - "revision": 1, - "explanation": "Bandwidth is read as the frequency difference between the two points on the curve at the specified level; at -60 dB the marked span is about 4 kHz.", - "source": "https://50ohm.de/A_slide_a_grundlegende_schaltungen.html", + "revision": 3, + "explanation": "Bandwidth is read as the frequency difference between the two points on the curve at the specified level; at -60 dB the marked span is about 4 kHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD219", "confidence": 7 }, "AD220": { - "revision": 1, - "explanation": "Filter bandwidth is the difference between the two frequencies where the voltage has fallen to 0.7 of the resonant maximum, the -3 dB points.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "Filter bandwidth is the difference between the two frequencies where the voltage has fallen to 0.7 of the resonant maximum, the -3 dB points. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD220", "confidence": 8 }, "AD221": { - "revision": 1, + "revision": 2, "explanation": "SSB speech typically needs about 2.4 to 2.7 kHz of filter bandwidth, so a 2.7 kHz crystal filter fits SSB operation.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD221", "confidence": 8 }, "AD222": { - "revision": 1, + "revision": 2, "explanation": "CW reception benefits from a narrow filter; 500 Hz is typical for separating Morse signals from nearby stations.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD222", "confidence": 8 }, "AD223": { - "revision": 1, - "explanation": "For a series resonant circuit, bandwidth is $B = R/(2 pi L)$; $10/(2 pi x 100 microhenry)$ is about 15.9 kHz.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "For a series resonant circuit, bandwidth is $B = R/(2 pi L)$; $10/(2 pi x 100 microhenry)$ is about 15.9 kHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD223", "confidence": 8 }, "AD224": { - "revision": 1, - "explanation": "For the parallel case, $B = 1/(2 pi R C)$; with 1 kOhm and 56 pF this is about 2.84 MHz.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "For the parallel case, $B = 1/(2 pi R C)$; with 1 kOhm and 56 pF this is about 2.84 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD224", "confidence": 8 }, "AD225": { - "revision": 1, - "explanation": "For the series circuit, Q is resonant frequency divided by bandwidth; about 159 kHz / 15.9 kHz = 10.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "For the series circuit, Q is resonant frequency divided by bandwidth; about 159 kHz / 15.9 kHz = 10. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD225", "confidence": 8 }, "AD226": { - "revision": 1, - "explanation": "For the parallel circuit, Q is resonant frequency divided by bandwidth; about 14.34 MHz / 2.84 MHz is about 5.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "revision": 2, + "explanation": "For the parallel circuit, Q is resonant frequency divided by bandwidth; about 14.34 MHz / 2.84 MHz is about 5. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD226", "confidence": 8 }, "AD227": { - "revision": 1, + "revision": 2, "explanation": "Looser coupling gives a narrower, lower transfer curve; in the shown family, curve c is less coupled than curve a.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD227", "confidence": 7 }, "AD228": { - "revision": 1, + "revision": 2, "explanation": "Critical coupling gives the flattest single peak at maximum useful width, while overcritical coupling creates the double-humped response; those are curves b and a respectively.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD228", "confidence": 7 }, "AD229": { - "revision": 1, + "revision": 2, "explanation": "Critical coupling is the coupling just before the response splits into a double hump: the curve has maximum width while the resonance maximum is still flat.", - "source": "https://50ohm.de/A_schwingkreis_2.html", + "source": "https://50ohm.de/NEA_schwingkreis_2.html#AD229", "confidence": 8 }, "AD301": { - "revision": 1, - "explanation": "In each series string the cell voltages add, giving $30 x 0.6 V = 18 V$; four identical strings in parallel add their short-circuit currents to 4 A.", - "source": "https://50ohm.de/A_slide_a_strom_spannungsversorgung.html", + "revision": 3, + "explanation": "In each series string the cell voltages add, giving $30 x 0.6 V = 18 V$; four identical strings in parallel add their short-circuit currents to 4 A. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_photovoltaik.html#AD301", "confidence": 7 }, "AD302": { - "revision": 1, - "explanation": "The unloaded smoothing capacitor charges close to the peak of the secondary AC voltage; about 15 V RMS times $sqrt(2)$ gives roughly 21 V.", - "source": "https://50ohm.de/A_slide_a_strom_spannungsversorgung.html", + "revision": 3, + "explanation": "The unloaded smoothing capacitor charges close to the peak of the secondary AC voltage; about 15 V RMS times $sqrt(2)$ gives roughly 21 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_gleichrichter_2.html#AD302", "confidence": 7 }, "AD303": { - "revision": 1, - "explanation": "A 20:1 transformer gives 230 V / 20 = 11.5 V RMS; the peak is about 16.3 V, and adding 50 percent safety gives about 24.4 V, so choose at least 25 V.", - "source": "https://50ohm.de/A_slide_a_strom_spannungsversorgung.html", + "revision": 3, + "explanation": "A 20:1 transformer gives 230 V / 20 = 11.5 V RMS; the peak is about 16.3 V, and adding 50 percent safety gives about 24.4 V, so choose at least 25 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_gleichrichter_2.html#AD303", "confidence": 7 }, "AD304": { - "revision": 1, + "revision": 2, "explanation": "A 5:1 transformer gives 46 V RMS, or about 65 V peak; the diode must withstand about twice that peak plus 20 percent, giving about 156 V.", - "source": "https://50ohm.de/A_slide_a_strom_spannungsversorgung.html", + "source": "https://50ohm.de/NEA_gleichrichter_2.html#AD304", "confidence": 7 }, "AD305": { - "revision": 1, + "revision": 2, "explanation": "In a bridge rectifier, two diodes conduct on each half-cycle so current through the load always has the same polarity; the correct diagram has all four diodes oriented for that path.", - "source": "https://50ohm.de/NEA_brueckengleichrichter.html", + "source": "https://50ohm.de/NEA_brueckengleichrichter.html#AD305", "confidence": 7 }, "AD306": { - "revision": 1, - "explanation": "The secondary peak is the mains peak divided by 8: $230 V x 1.414 / 8$ is about 40.6 V, which is the unloaded capacitor voltage.", - "source": "https://50ohm.de/NEA_brueckengleichrichter.html", + "revision": 2, + "explanation": "The secondary peak is the mains peak divided by 8: $230 V x 1.414 / 8$ is about 40.6 V, which is the unloaded capacitor voltage. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_brueckengleichrichter.html#AD306", "confidence": 7 }, "AD307": { - "revision": 1, + "revision": 2, "explanation": "A full-wave rectifier uses both half-cycles and routes them through the load with the indicated same output polarity.", - "source": "https://50ohm.de/NEA_vollweggleichrichter.html", + "source": "https://50ohm.de/NEA_vollweggleichrichter.html#AD307", "confidence": 7 }, "AD308": { - "revision": 1, + "revision": 2, "explanation": "The rectifier output is pulsating DC: the negative half-cycles are folded to the same polarity rather than appearing as negative voltage.", - "source": "https://50ohm.de/NEA_vollweggleichrichter.html", + "source": "https://50ohm.de/NEA_vollweggleichrichter.html#AD308", "confidence": 7 }, "AD309": { - "revision": 1, - "explanation": "The ripple span is the difference between the high and low points, 3 V, and a full-wave rectifier on 50 Hz mains produces ripple at 100 Hz.", - "source": "https://50ohm.de/A_slide_a_strom_spannungsversorgung.html", + "revision": 3, + "explanation": "The ripple span is the difference between the high and low points, 3 V, and a full-wave rectifier on 50 Hz mains produces ripple at 100 Hz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_restwelligkeit.html#AD309", "confidence": 7 }, "AD310": { - "revision": 1, - "explanation": "A full-wave rectifier produces one output pulse for each half-cycle, so 50 Hz mains becomes 100 Hz ripple frequency.", - "source": "https://50ohm.de/NEA_vollweggleichrichter.html", + "revision": 3, + "explanation": "A full-wave rectifier produces one output pulse for each half-cycle, so 50 Hz mains becomes 100 Hz ripple frequency. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_restwelligkeit.html#AD310", "confidence": 8 }, "AD311": { - "revision": 1, + "revision": 2, "explanation": "In a switch-mode supply the electronic switch controls energy transfer by changing pulse width, so block E acts as the pulse-width modulator.", - "source": "https://50ohm.de/A_schaltnetzteil_2.html", + "source": "https://50ohm.de/NEA_schaltnetzteil_2.html#AD311", "confidence": 7 }, "AD312": { - "revision": 1, + "revision": 2, "explanation": "The fast switching action produces harmonics and broadband unwanted spectral components, which is the main EMC disadvantage of the shown switch-mode supply.", - "source": "https://50ohm.de/A_schaltnetzteil_2.html", + "source": "https://50ohm.de/NEA_schaltnetzteil_2.html#AD312", "confidence": 7 }, "AD313": { - "revision": 2, + "revision": 3, "explanation": "Spurs spaced 120 kHz apart across the spectrum point to a switch-mode supply: its switching frequency and harmonics radiate at multiples of that fundamental rate.", - "source": "https://50ohm.de/A_schaltnetzteil_2.html", + "source": "https://50ohm.de/NEA_schaltnetzteil_2.html#AD313", "confidence": 8 }, "AD314": { - "revision": 1, + "revision": 2, "explanation": "A mains input filter uses a common-mode choke and capacitors to keep switching interference from being conducted back into the power network.", - "source": "https://50ohm.de/A_schaltnetzteil_2.html", + "source": "https://50ohm.de/NEA_schaltnetzteil_2.html#AD314", "confidence": 7 }, "AD315": { - "revision": 1, - "explanation": "The Z-diode regulator clamps the output near the Zener voltage, so the output between A and B is approximately 5 V despite the varying input.", - "source": "https://50ohm.de/A_spannungsstabilisierung.html", + "revision": 3, + "explanation": "The Z-diode regulator clamps the output near the Zener voltage, so the output between A and B is approximately 5 V despite the varying input. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsstabilisierung.html#AD315", "confidence": 7 }, "AD316": { - "revision": 1, + "revision": 2, "explanation": "A linear regulator needs headroom: its input voltage must be higher than the regulated output voltage so the pass element can control the drop.", - "source": "https://50ohm.de/A_spannungsstabilisierung.html", + "source": "https://50ohm.de/NEA_spannungsstabilisierung.html#AD316", "confidence": 7 }, "AD317": { - "revision": 1, + "revision": 2, "explanation": "A fixed 12 V regulator absorbs the allowed input variation as internal voltage drop, so the output variation is nearly zero while it remains in regulation.", - "source": "https://50ohm.de/A_spannungsstabilisierung.html", + "source": "https://50ohm.de/NEA_spannungsstabilisierung.html#AD317", "confidence": 7 }, "AD318": { - "revision": 1, - "explanation": "The load current is $5 V / 10 ohm = 0.5 A$ and the regulator drops $13.8 V - 5 V = 8.8 V$; loss is $8.8 V x 0.5 A = 4.4 W$.", - "source": "https://50ohm.de/A_spannungsstabilisierung.html", + "revision": 3, + "explanation": "The load current is $5 V / 10 ohm = 0.5 A$ and the regulator drops $13.8 V - 5 V = 8.8 V$; loss is $8.8 V x 0.5 A = 4.4 W$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsstabilisierung.html#AD318", "confidence": 7 }, "AD319": { - "revision": 1, - "explanation": "A linear regulator dissipates the voltage drop times current: $(13.8 V - 9 V) x 0.9 A = 4.32 W$.", - "source": "https://50ohm.de/A_spannungsstabilisierung.html", + "revision": 3, + "explanation": "A linear regulator dissipates the voltage drop times current: $(13.8 V - 9 V) x 0.9 A = 4.32 W$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsstabilisierung.html#AD319", "confidence": 8 }, "AD320": { - "revision": 1, + "revision": 2, "explanation": "Efficiency is output power over input power: $5 V x 0.450 A$ divided by $13.8 V x 0.455 A$ is about 0.36.", - "source": "https://50ohm.de/A_spannungsstabilisierung.html", + "source": "https://50ohm.de/NEA_spannungsstabilisierung.html#AD320", "confidence": 8 }, "AD321": { - "revision": 1, - "explanation": "The load power is $4.7 V x 10 mA = 47 mW$; input power is $13.8 V x (10 + 15) mA = 345 mW$, so efficiency is about 0.14.", - "source": "https://50ohm.de/A_spannungsstabilisierung.html", + "revision": 2, + "explanation": "The load power is $4.7 V x 10 mA = 47 mW$; input power is $13.8 V x (10 + 15) mA = 345 mW$, so efficiency is about 0.14. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsstabilisierung.html#AD321", "confidence": 7 }, "AD322": { - "revision": 1, + "revision": 2, "explanation": "A Bias-T combines DC feed and RF signal on one cable while separating them again at the ports with an inductor and capacitor.", - "source": "https://50ohm.de/NEA_fernspeiseweiche.html", + "source": "https://50ohm.de/NEA_fernspeiseweiche.html#AD322", "confidence": 8 }, "AD323": { - "revision": 1, + "revision": 2, "explanation": "The circuit combines a DC feed path through an inductor with an RF path through a coupling capacitor, which is the structure of a Bias-T.", - "source": "https://50ohm.de/NEA_fernspeiseweiche.html", + "source": "https://50ohm.de/NEA_fernspeiseweiche.html#AD323", "confidence": 7 }, "AD324": { - "revision": 1, - "explanation": "C1 is the RF coupling capacitor toward the receiver; it passes RF but blocks the DC supply from reaching the receiver input.", - "source": "https://50ohm.de/NEA_fernspeiseweiche.html", + "revision": 2, + "explanation": "C1 is the RF coupling capacitor toward the receiver; it passes RF but blocks the DC supply from reaching the receiver input. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_fernspeiseweiche.html#AD324", "confidence": 7 }, "AD325": { - "revision": 1, + "revision": 2, "explanation": "The Bias-T inductor is in the DC feed path, so it must safely carry the supply current for the remote device.", - "source": "https://50ohm.de/NEA_fernspeiseweiche.html", + "source": "https://50ohm.de/NEA_fernspeiseweiche.html#AD325", "confidence": 7 }, "AD401": { - "revision": 1, + "revision": 2, "explanation": "The collector is the AC-common terminal and the output is taken from the emitter, so this is the collector configuration, also called an emitter follower.", - "source": "https://50ohm.de/A_kollektorschaltung.html", + "source": "https://50ohm.de/NEA_kollektorschaltung.html#AD401", "confidence": 7 }, "AD402": { - "revision": 1, - "explanation": "An emitter follower has voltage gain just below unity because the emitter follows the base voltage, and it is non-inverting, so the phase shift is 0 degrees.", - "source": "https://50ohm.de/A_kollektorschaltung.html", + "revision": 2, + "explanation": "An emitter follower has voltage gain just below unity because the emitter follows the base voltage, and it is non-inverting, so the phase shift is 0 degrees. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kollektorschaltung.html#AD402", "confidence": 7 }, "AD403": { - "revision": 1, + "revision": 2, "explanation": "A collector configuration buffers a high-impedance source into a low-impedance load; its current gain is useful even though voltage gain is below one.", - "source": "https://50ohm.de/A_kollektorschaltung.html", + "source": "https://50ohm.de/NEA_kollektorschaltung.html#AD403", "confidence": 7 }, "AD404": { - "revision": 1, + "revision": 2, "explanation": "Because it has high input impedance and low output impedance, an emitter follower can isolate an oscillator from changing load impedance.", - "source": "https://50ohm.de/A_kollektorschaltung.html", + "source": "https://50ohm.de/NEA_kollektorschaltung.html#AD404", "confidence": 7 }, "AD405": { - "revision": 1, + "revision": 2, "explanation": "In a collector configuration the emitter voltage rises and falls with the base signal, so input and output have the same phase.", - "source": "https://50ohm.de/A_kollektorschaltung.html", + "source": "https://50ohm.de/NEA_kollektorschaltung.html#AD405", "confidence": 8 }, "AD406": { - "revision": 1, - "explanation": "Without DC bias the transistor conducts only when the base-emitter voltage exceeds about 0.6 V; the collector voltage then dips, so the output is a clipped, inverted pulse-like waveform.", - "source": "https://50ohm.de/A_emitterschaltung.html", + "revision": 2, + "explanation": "Without DC bias the transistor conducts only when the base-emitter voltage exceeds about 0.6 V; the collector voltage then dips, so the output is a clipped, inverted pulse-like waveform. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_emitterschaltung.html#AD406", "confidence": 7 }, "AD407": { - "revision": 1, + "revision": 2, "explanation": "In an emitter configuration, increasing base current increases collector current and therefore the voltage drop across the collector resistor; the collector output voltage moves oppositely, giving 180 degrees phase shift.", - "source": "https://50ohm.de/A_emitterschaltung.html", + "source": "https://50ohm.de/NEA_emitterschaltung.html#AD407", "confidence": 8 }, "AD408": { - "revision": 1, - "explanation": "The emitter-stage output is taken at the collector, so the collector waveform is inverted relative to the input while the bias and coupling points keep their shown DC roles.", - "source": "https://50ohm.de/A_emitterschaltung.html", + "revision": 2, + "explanation": "The emitter-stage output is taken at the collector, so the collector waveform is inverted relative to the input while the bias and coupling points keep their shown DC roles. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_emitterschaltung.html#AD408", "confidence": 7 }, "AD409": { - "revision": 1, + "revision": 2, "explanation": "The emitter is the common reference for input and output, with the output taken at the collector through a coupling capacitor, which identifies an emitter configuration.", - "source": "https://50ohm.de/A_emitterschaltung.html", + "source": "https://50ohm.de/NEA_emitterschaltung.html#AD409", "confidence": 7 }, "AD410": { - "revision": 1, - "explanation": "A bypassed emitter stage can provide large voltage gain, and the collector output is inverted relative to the base input, so the phase shift is 180 degrees.", - "source": "https://50ohm.de/A_emitterschaltung.html", + "revision": 2, + "explanation": "A bypassed emitter stage can provide large voltage gain, and the collector output is inverted relative to the base input, so the phase shift is 180 degrees. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_emitterschaltung.html#AD410", "confidence": 7 }, "AD411": { - "revision": 1, - "explanation": "R1 and R2 form a voltage divider feeding the base, setting the transistor's DC bias point before the AC signal is applied.", - "source": "https://50ohm.de/A_emitterschaltung.html", + "revision": 2, + "explanation": "R1 and R2 form a voltage divider feeding the base, setting the transistor's DC bias point before the AC signal is applied. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_emitterschaltung.html#AD411", "confidence": 7 }, "AD412": { - "revision": 1, - "explanation": "The coupling capacitors pass the AC signal into and out of the stage while blocking the DC bias voltages from adjacent circuits.", - "source": "https://50ohm.de/A_emitterschaltung.html", + "revision": 2, + "explanation": "The coupling capacitors pass the AC signal into and out of the stage while blocking the DC bias voltages from adjacent circuits. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_emitterschaltung.html#AD412", "confidence": 7 }, "AD413": { - "revision": 1, - "explanation": "The emitter bypass capacitor shorts the emitter resistor for AC, reducing emitter degeneration and therefore maximizing AC voltage gain.", - "source": "https://50ohm.de/A_emitterschaltung.html", + "revision": 2, + "explanation": "The emitter bypass capacitor shorts the emitter resistor for AC, reducing emitter degeneration and therefore maximizing AC voltage gain. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_emitterschaltung.html#AD413", "confidence": 7 }, "AD414": { - "revision": 1, - "explanation": "Removing the emitter bypass capacitor leaves the emitter resistor active for AC feedback, so emitter degeneration lowers the voltage gain.", - "source": "https://50ohm.de/A_emitterschaltung.html", + "revision": 2, + "explanation": "Removing the emitter bypass capacitor leaves the emitter resistor active for AC feedback, so emitter degeneration lowers the voltage gain. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_emitterschaltung.html#AD414", "confidence": 7 }, "AD415": { - "revision": 1, + "revision": 2, "explanation": "With no emitter bypass capacitor, the emitter resistor provides negative feedback and the stage gain drops from a large value to roughly the resistor-ratio value, about 10 here.", - "source": "https://50ohm.de/A_emitterschaltung.html", + "source": "https://50ohm.de/NEA_emitterschaltung.html#AD415", "confidence": 7 }, "AD416": { - "revision": 1, - "explanation": "Moving the bias point upward increases the conduction angle: C is below cutoff most of the cycle, B sits at cutoff, AB is slightly above it, and A conducts for the whole cycle.", - "source": "https://50ohm.de/A_verstaerker_klasse.html", + "revision": 2, + "explanation": "Moving the bias point upward increases the conduction angle: C is below cutoff most of the cycle, B sits at cutoff, AB is slightly above it, and A conducts for the whole cycle. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AD416", "confidence": 7 }, "AD417": { - "revision": 1, + "revision": 2, "explanation": "A bipolar transistor's collector current is controlled by base-emitter voltage, so raising that voltage in B operation drives the transistor harder and greatly increases collector current.", - "source": "https://50ohm.de/A_verstaerker_klasse.html", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AD417", "confidence": 8 }, "AD418": { - "revision": 1, + "revision": 2, "explanation": "Class C is biased below cutoff; with no drive the transistor does not conduct, so the quiescent current is approximately zero.", - "source": "https://50ohm.de/A_verstaerker_klasse.html", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AD418", "confidence": 8 }, "AD419": { - "revision": 1, + "revision": 2, "explanation": "Class A keeps the device conducting over the full signal cycle, giving good linearity and low harmonics at the cost of high quiescent current and poor efficiency around 40%.", - "source": "https://50ohm.de/A_verstaerker_klasse.html", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AD419", "confidence": 8 }, "AD420": { - "revision": 1, + "revision": 2, "explanation": "Class B biases near cutoff so quiescent current is very small; with push-pull operation it can be fairly linear and efficient, up to about 80%.", - "source": "https://50ohm.de/A_verstaerker_klasse.html", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AD420", "confidence": 8 }, "AD421": { - "revision": 1, + "revision": 2, "explanation": "Class C conducts for less than half the cycle, so it is very efficient but strongly nonlinear, producing many harmonics and no quiescent current.", - "source": "https://50ohm.de/A_verstaerker_klasse.html", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AD421", "confidence": 8 }, "AD422": { - "revision": 1, + "revision": 2, "explanation": "SSB needs linear amplification because information is carried in amplitude and phase; class C is nonlinear, while A, AB, and B can be used for linear RF power stages.", - "source": "https://50ohm.de/A_verstaerker_klasse.html", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AD422", "confidence": 8 }, "AD423": { - "revision": 1, + "revision": 2, "explanation": "Overdrive pushes a nominally linear AB amplifier into nonlinear operation; distorted SSB creates unwanted side products that appear as splatter on adjacent frequencies.", - "source": "https://50ohm.de/A_verstaerker_klasse.html", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AD423", "confidence": 8 }, "AD424": { - "revision": 1, - "explanation": "The DC input power is $50 V x 2 A = 100 W$; class A efficiency is about 40%, so expected RF output is about $0.4 x 100 W = 40 W$.", - "source": "https://50ohm.de/A_verstaerker_wirkungsgrad.html", + "revision": 2, + "explanation": "The DC input power is $50 V x 2 A = 100 W$; class A efficiency is about 40%, so expected RF output is about $0.4 x 100 W = 40 W$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AD424", "confidence": 8 }, "AD425": { - "revision": 1, - "explanation": "The DC input power is $50 V x 2 A = 100 W$; using about 85% efficiency for class C gives about $0.85 x 100 W = 85 W$ RF output.", - "source": "https://50ohm.de/A_verstaerker_wirkungsgrad.html", + "revision": 2, + "explanation": "The DC input power is $50 V x 2 A = 100 W$; using about 85% efficiency for class C gives about $0.85 x 100 W = 85 W$ RF output. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AD425", "confidence": 8 }, "AD426": { - "revision": 1, - "explanation": "A 16 dB power gain is a ratio of $10^(16/10) = 39.8$, so 1 W input becomes about 40 W output.", - "source": "https://50ohm.de/A_verstaerkungsleistung.html", + "revision": 3, + "explanation": "A 16 dB power gain is a ratio of $10^(16/10) = 39.8$, so 1 W input becomes about 40 W output. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verstaerkungsleistung.html#AD426", "confidence": 8 }, "AD427": { - "revision": 1, - "explanation": "For equal impedances, voltage gain in dB is $20 log10(U2/U1)$; $20 log10(4 mV / 1 mV) = 20 log10(4) = 12 dB$.", - "source": "https://50ohm.de/A_verstaerkungsleistung.html", + "revision": 3, + "explanation": "For equal impedances, voltage gain in dB is $20 log10(U2/U1)$; $20 log10(4 mV / 1 mV) = 20 log10(4) = 12 dB$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verstaerkungsleistung.html#AD427", "confidence": 8 }, "AD428": { - "revision": 1, - "explanation": "Power gain in dB is $10 log10(P2/P1)$; $10 log10(38 W / 2.5 W) = 10 log10(15.2) = 11.8 dB$.", - "source": "https://50ohm.de/A_verstaerkungsleistung.html", + "revision": 3, + "explanation": "Power gain in dB is $10 log10(P2/P1)$; $10 log10(38 W / 2.5 W) = 10 log10(15.2) = 11.8 dB$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verstaerkungsleistung.html#AD428", "confidence": 8 }, "AD429": { - "revision": 1, + "revision": 2, "explanation": "Efficiency is useful RF output divided by DC input: $10 W / 25 W = 0.40$, or 40%.", - "source": "https://50ohm.de/A_verstaerker_wirkungsgrad.html", + "source": "https://50ohm.de/NEA_verstaerker_wirkungsgrad.html#AD429", "confidence": 8 }, "AD430": { - "revision": 1, + "revision": 2, "explanation": "The DC input power is $12.5 V x 16 A = 200 W$; efficiency is $90 W / 200 W = 0.45$, or 45%.", - "source": "https://50ohm.de/A_verstaerker_wirkungsgrad.html", + "source": "https://50ohm.de/NEA_verstaerker_wirkungsgrad.html#AD430", "confidence": 8 }, "AD431": { - "revision": 1, + "revision": 2, "explanation": "Linear amplification scales the input waveform without changing its shape, so the output curve follows the same waveform at a larger amplitude.", - "source": "https://50ohm.de/A_verstaerker_linearverstaerker.html", + "source": "https://50ohm.de/NEA_verstaerker_linearverstaerker.html#AD431", "confidence": 8 }, "AD432": { - "revision": 1, + "revision": 2, "explanation": "Self-oscillation happens when output energy is coupled back to the input with enough gain and phase to act as feedback, turning the amplifier into an unintended oscillator.", - "source": "https://50ohm.de/A_verstaerker_eigenschwingung.html", + "source": "https://50ohm.de/NEA_verstaerker_eigenschwingung.html#AD432", "confidence": 8 }, "AD433": { - "revision": 1, + "revision": 2, "explanation": "A microphone amplifier should pass the speech band while attenuating both too-low and too-high audio frequencies, which is exactly a band-pass response.", - "source": "https://50ohm.de/A_slide_a_grundlegende_schaltungen.html", + "source": "https://50ohm.de/NEA_verstaerker_begrenzung_bandbreite.html#AD433", "confidence": 7 }, "AD501": { - "revision": 1, + "revision": 2, "explanation": "A diode followed by an RC load recovers the envelope of an AM signal, so the circuit is an envelope demodulator for AM.", - "source": "https://50ohm.de/EA_demodulator.html", + "source": "https://50ohm.de/NEA_demodulator.html#AD501", "confidence": 7 }, "AD502": { - "revision": 1, + "revision": 2, "explanation": "At point X the diode has rectified the AM IF waveform but the RC network has not yet fully smoothed it, so the signal follows the positive envelope with RF ripple remaining.", - "source": "https://50ohm.de/EA_demodulator.html", + "source": "https://50ohm.de/NEA_demodulator.html#AD502", "confidence": 7 }, "AD503": { - "revision": 1, + "revision": 2, "explanation": "In an envelope detector the extra output from the rectified envelope can be filtered into a DC control voltage, which is used as an AGC/regulating voltage.", - "source": "https://50ohm.de/EA_demodulator.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AD503", "confidence": 7 }, "AD504": { - "revision": 2, + "revision": 3, "explanation": "A tuned circuit offset from the IF converts FM frequency deviation, German Hub/Frequenzhub, into amplitude changes. A diode detector can then recover those amplitude changes as audio; that method is a slope discriminator.", - "source": "https://50ohm.de/EA_demodulator.html", + "source": "https://50ohm.de/NEA_demodulator.html#AD504", "confidence": 7 }, "AD505": { - "revision": 1, + "revision": 2, "explanation": "A PLL can follow the frequency of an FM signal; the VCO control voltage is then proportional to the original modulation, so the block is a PLL FM demodulator.", - "source": "https://50ohm.de/EA_demodulator.html", + "source": "https://50ohm.de/NEA_demodulator.html#AD505", "confidence": 7 }, "AD506": { - "revision": 1, + "revision": 2, "explanation": "A product detector mixes the SSB signal with a locally regenerated carrier/BFO so the sideband is converted back to audio.", - "source": "https://50ohm.de/EA_demodulator.html", + "source": "https://50ohm.de/NEA_demodulator.html#AD506", "confidence": 7 }, "AD507": { - "revision": 1, + "revision": 2, "explanation": "The circuit varies the RF carrier amplitude in step with the audio signal, which is the defining operation of an AM modulator.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AD507", "confidence": 7 }, "AD508": { - "revision": 1, + "revision": 2, "explanation": "The audio voltage drives a varicap in the oscillator tank circuit; changing capacitance changes oscillator frequency, so the generated signal is FM.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AD508", "confidence": 7 }, "AD509": { - "revision": 2, + "revision": 3, "explanation": "For FM, German Hub or Frequenzhub means frequency deviation: the maximum shift of the carrier above and below its centre frequency. The audio amplitude sets that deviation; the antiparallel diodes and level control limit it so the FM signal does not become too wide.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AD509", "confidence": 8 }, "AD510": { - "revision": 1, + "revision": 2, "explanation": "A balanced mixer cancels the carrier when adjusted symmetrically; the sum and difference products remain as the two AM sidebands.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AD510", "confidence": 8 }, "AD601": { - "revision": 1, + "revision": 2, "explanation": "A VCO is voltage controlled: a control voltage changes a tuning element such as a varicap, and the oscillator frequency follows that voltage.", - "source": "https://50ohm.de/A_oszillator_vco.html", + "source": "https://50ohm.de/NEA_oszillator_vco.html#AD601", "confidence": 8 }, "AD602": { - "revision": 1, + "revision": 2, "explanation": "TCXO means Temperature Compensated Crystal Oscillator: a crystal oscillator whose circuit compensates temperature effects instead of holding the whole oscillator in an oven.", - "source": "https://50ohm.de/A_oszillator_tcxo_ocxo.html", + "source": "https://50ohm.de/NEA_oszillator_tcxo_ocxo.html#AD602", "confidence": 8 }, "AD603": { - "revision": 1, + "revision": 2, "explanation": "The abbreviation TCXO expands to Temperature Compensated Crystal Oscillator, i.e. a temperature-compensated crystal oscillator.", - "source": "https://50ohm.de/A_oszillator_tcxo_ocxo.html", + "source": "https://50ohm.de/NEA_oszillator_tcxo_ocxo.html#AD603", "confidence": 8 }, "AD604": { - "revision": 1, + "revision": 2, "explanation": "At 3 cm, small reference errors are multiplied into large RF errors; SSB/SDR operation therefore needs a stable reference, and TCXO is the stable choice among the listed options.", - "source": "https://50ohm.de/A_oszillator_tcxo_ocxo.html", + "source": "https://50ohm.de/NEA_oszillator_tcxo_ocxo.html#AD604", "confidence": 8 }, "AD605": { - "revision": 1, + "revision": 2, "explanation": "An OCXO keeps the crystal oscillator at a controlled oven temperature, so it is more stable than a plain XO, a TCXO, or a VCO.", - "source": "https://50ohm.de/A_oszillator_tcxo_ocxo.html", + "source": "https://50ohm.de/NEA_oszillator_tcxo_ocxo.html#AD605", "confidence": 8 }, "AD606": { - "revision": 1, + "revision": 2, "explanation": "A GPSDO combines a stable local oscillator for short-term stability with a GPS-derived external reference for long-term correction.", - "source": "https://50ohm.de/A_oszillator_gpsdo.html", + "source": "https://50ohm.de/NEA_oszillator_gpsdo.html#AD606", "confidence": 8 }, "AD607": { - "revision": 1, + "revision": 2, "explanation": "A VFO's frequency depends partly on its operating voltage; stabilized DC prevents supply changes from pulling the oscillator frequency.", - "source": "https://50ohm.de/A_oszillator_spannungsstabilitaet.html", + "source": "https://50ohm.de/NEA_oszillator_spannungsstabilitaet.html#AD607", "confidence": 8 }, "AD608": { - "revision": 1, + "revision": 2, "explanation": "The VFO needs voltage-stabilized DC because oscillator frequency can shift when the supply voltage changes.", - "source": "https://50ohm.de/A_oszillator_spannungsstabilitaet.html", + "source": "https://50ohm.de/NEA_oszillator_spannungsstabilitaet.html#AD608", "confidence": 8 }, "AD609": { - "revision": 1, + "revision": 2, "explanation": "CW keying can momentarily change oscillator supply voltage; if the oscillator frequency jumps with those voltage changes, the note sounds like chirp.", - "source": "https://50ohm.de/A_oszillator_spannungsstabilitaet.html", + "source": "https://50ohm.de/NEA_oszillator_spannungsstabilitaet.html#AD609", "confidence": 8 }, "AD610": { - "revision": 1, + "revision": 2, "explanation": "A buffer stage isolates the oscillator from following stages, so load changes cannot easily pull the oscillator frequency.", - "source": "https://50ohm.de/EA_oszillator_schaltungen.html", + "source": "https://50ohm.de/NEA_oszillator_schaltungen.html#AD610", "confidence": 8 }, "AD611": { - "revision": 1, + "revision": 2, "explanation": "Unwanted RF feedback into a VFO changes the conditions in the oscillator circuit, which can pull or modulate the generated frequency.", - "source": "https://50ohm.de/A_oszillator_vco.html", + "source": "https://50ohm.de/NEA_oszillator_vco.html#AD611", "confidence": 8 }, "AD612": { - "revision": 1, + "revision": 2, "explanation": "PA current and RF can disturb a shared supply; filtering and decoupling the VFO supply keeps those disturbances from pulling the oscillator.", - "source": "https://50ohm.de/A_oszillator_spannungsstabilitaet.html", + "source": "https://50ohm.de/NEA_oszillator_spannungsstabilitaet.html#AD612", "confidence": 8 }, "AD613": { - "revision": 1, + "revision": 2, "explanation": "Sustained oscillation needs positive feedback at the oscillation frequency: the returned signal must be in phase and at least as large as the signal it reinforces.", - "source": "https://50ohm.de/EA_oszillator_schaltungen.html", + "source": "https://50ohm.de/NEA_oszillator_schaltungen.html#AD613", "confidence": 8 }, "AD614": { - "revision": 1, + "revision": 2, "explanation": "The LC resonator and capacitive divider form a Colpitts-style three-point oscillator, with the capacitive divider providing the feedback path.", - "source": "https://50ohm.de/EA_oszillator_schaltungen.html", + "source": "https://50ohm.de/NEA_oszillator_schaltungen.html#AD614", "confidence": 7 }, "AD615": { - "revision": 1, + "revision": 2, "explanation": "The output should be taken at the low-impedance buffered point so the load disturbs the resonant circuit as little as possible; in the drawing that is point D.", - "source": "https://50ohm.de/EA_oszillator_schaltungen.html", + "source": "https://50ohm.de/NEA_oszillator_schaltungen.html#AD615", "confidence": 7 }, "AD616": { - "revision": 1, - "explanation": "C1 and C2 form the capacitive voltage divider of the Colpitts oscillator; a fraction of the output is fed back to sustain oscillation.", - "source": "https://50ohm.de/EA_oszillator_schaltungen.html", + "revision": 2, + "explanation": "C1 and C2 form the capacitive voltage divider of the Colpitts oscillator; a fraction of the output is fed back to sustain oscillation. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_oszillator_schaltungen.html#AD616", "confidence": 7 }, "AD617": { - "revision": 1, + "revision": 2, "explanation": "The transistor is used in collector configuration and the crystal sets the oscillation frequency; this circuit is a capacitively fed crystal oscillator on the crystal's fundamental frequency.", - "source": "https://50ohm.de/EA_oszillator_schaltungen.html", + "source": "https://50ohm.de/NEA_oszillator_schaltungen.html#AD617", "confidence": 7 }, "AD618": { - "revision": 1, + "revision": 2, "explanation": "Point 3 is part of the frequency-determining resonant network; probe capacitance loads that point and therefore shifts the oscillator frequency.", - "source": "https://50ohm.de/EA_oszillator_schaltungen.html", + "source": "https://50ohm.de/NEA_oszillator_schaltungen.html#AD618", "confidence": 7 }, "AD619": { - "revision": 1, + "revision": 2, "explanation": "The oscillator should be measured at the buffered output point, because probing the resonant circuit directly would add capacitance and detune it; in the drawing that is point 4.", - "source": "https://50ohm.de/EA_oszillator_schaltungen.html", + "source": "https://50ohm.de/NEA_oszillator_schaltungen.html#AD619", "confidence": 7 }, "AD620": { - "revision": 1, + "revision": 2, "explanation": "The block diagram uses a clock, digital address/phase generation, a sine lookup table, and a D/A converter to synthesize the output, which is direct digital synthesis.", - "source": "https://50ohm.de/A_oszillator_dds.html", + "source": "https://50ohm.de/NEA_oszillator_dds.html#AD620", "confidence": 7 }, "AD701": { - "revision": 1, + "revision": 2, "explanation": "A basic PLL compares phase, filters the phase-detector output into a control voltage, and uses that voltage to steer a VCO.", - "source": "https://50ohm.de/A_oszillator_pll.html", + "source": "https://50ohm.de/NEA_oszillator_pll.html#AD701", "confidence": 8 }, "AD702": { - "revision": 1, + "revision": 2, "explanation": "In lock, the phase detector sees equal reference and divided-VCO frequencies, so the signals at the two detector inputs A and B have the same frequency.", - "source": "https://50ohm.de/A_oszillator_pll.html", + "source": "https://50ohm.de/NEA_oszillator_pll.html#AD702", "confidence": 7 }, "AD703": { - "revision": 1, - "explanation": "In this integer-N PLL, the smallest output step equals the reference frequency at the phase detector, so a 12.5 kHz channel spacing requires 12.5 kHz at point A.", - "source": "https://50ohm.de/A_oszillator_pll.html", + "revision": 3, + "explanation": "In this integer-N PLL, the smallest output step equals the reference frequency at the phase detector, so a 12.5 kHz channel spacing requires 12.5 kHz at point A. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_oszillator_pll.html#AD703", "confidence": 7 }, "AD704": { - "revision": 1, + "revision": 2, "explanation": "The divider ratio is output frequency divided by the 12.5 kHz reference: 12.000 MHz / 12.5 kHz = 960 and 14.000 MHz / 12.5 kHz = 1120.", - "source": "https://50ohm.de/A_oszillator_pll.html", + "source": "https://50ohm.de/NEA_oszillator_pll.html#AD704", "confidence": 7 }, "AD705": { - "revision": 1, + "revision": 2, "explanation": "A synthesizer locks its output to the reference oscillator, so long-term accuracy and stability mainly follow the quartz reference, not the VCO or dividers.", - "source": "https://50ohm.de/A_oszillator_pll.html", + "source": "https://50ohm.de/NEA_oszillator_pll.html#AD705", "confidence": 8 }, "AD801": { - "revision": 1, + "revision": 2, "explanation": "The drawing is a resistive pad: only resistors are arranged between input and output to reduce signal level while maintaining impedance.", - "source": "https://50ohm.de/A_daempfungsglieder.html", + "source": "https://50ohm.de/NEA_daempfungsglieder.html#AD801", "confidence": 7 }, "AD802": { - "revision": 1, + "revision": 2, "explanation": "The circuit is a resistive attenuator, not a frequency-selective filter, because its resistor network dissipates part of the RF power as heat.", - "source": "https://50ohm.de/A_daempfungsglieder.html", + "source": "https://50ohm.de/NEA_daempfungsglieder.html#AD802", "confidence": 7 }, "AD803": { - "revision": 1, - "explanation": "For power ratios, 20 dB corresponds to $10^(20/10) = 100$, so input power is 100 times the load power.", - "source": "https://50ohm.de/A_daempfungsglieder.html", + "revision": 2, + "explanation": "For power ratios, 20 dB corresponds to $10^(20/10) = 100$, so input power is 100 times the load power. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_daempfungsglieder.html#AD803", "confidence": 7 }, "AD804": { - "revision": 1, - "explanation": "For power ratios, 6 dB corresponds approximately to $10^(6/10) = 3.98$, so the practical ratio is 4.", - "source": "https://50ohm.de/A_daempfungsglieder.html", + "revision": 2, + "explanation": "For power ratios, 6 dB corresponds approximately to $10^(6/10) = 3.98$, so the practical ratio is 4. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_daempfungsglieder.html#AD804", "confidence": 7 }, "AD805": { - "revision": 1, - "explanation": "A symmetrical attenuator designed for a 50 ohm system presents 50 ohm at its input when its output is terminated with the matching 50 ohm load.", - "source": "https://50ohm.de/A_daempfungsglieder.html", + "revision": 2, + "explanation": "A symmetrical attenuator designed for a 50 ohm system presents 50 ohm at its input when its output is terminated with the matching 50 ohm load. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_daempfungsglieder.html#AD805", "confidence": 7 }, "AD806": { - "revision": 1, - "explanation": "A 20 dB attenuator reduces power by a factor of 100, so 100 W input leaves 1 W at the matched load; the remaining 99 W is dissipated as heat in the pad.", - "source": "https://50ohm.de/A_daempfungsglieder.html", + "revision": 2, + "explanation": "A 20 dB attenuator reduces power by a factor of 100, so 100 W input leaves 1 W at the matched load; the remaining 99 W is dissipated as heat in the pad. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_daempfungsglieder.html#AD806", "confidence": 7 }, "AE101": { - "revision": 2, + "revision": 3, "explanation": "AFuV defines occupied bandwidth so that the mean power below the lower limit and above the upper limit is 0.5% each of the total mean transmitted power.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__2.html", + "source": "https://50ohm.de/NEA_bandreite_3.html#AE101", "confidence": 10 }, "AE201": { - "revision": 1, + "revision": 2, "explanation": "At 100% AM modulation the envelope just reaches zero at its minimum but does not cross or flatten; that is the largest undistorted AM modulation depth.", - "source": "https://50ohm.de/A_am_2.html", + "source": "https://50ohm.de/NEA_am_2.html#AE201", "confidence": 7 }, "AE202": { - "revision": 1, + "revision": 2, "explanation": "AM modulation depth is the modulation-envelope amplitude divided by the carrier amplitude; the oscilloscope shows about 3 V modulation on a 6 V carrier, giving 0.5 or 50%.", - "source": "https://50ohm.de/A_am_2.html", + "source": "https://50ohm.de/NEA_am_2.html#AE202", "confidence": 7 }, "AE203": { - "revision": 1, + "revision": 2, "explanation": "Overmodulation is AM with modulation depth above 100%; the envelope is driven through zero or pinched off, which causes distortion and sideband splatter.", - "source": "https://50ohm.de/A_am_2.html", + "source": "https://50ohm.de/NEA_am_2.html#AE203", "confidence": 7 }, "AE204": { - "revision": 1, + "revision": 2, "explanation": "AM above 100% modulation overdrives the envelope and creates distortion products, so the modulation depth must stay below 100% to avoid splatter.", - "source": "https://50ohm.de/A_am_2.html", + "source": "https://50ohm.de/NEA_am_2.html#AE204", "confidence": 8 }, "AE205": { - "revision": 1, + "revision": 2, "explanation": "Overmodulating SSB makes the signal path nonlinear; the resulting distortion spreads energy outside the intended sideband as splatter.", - "source": "https://50ohm.de/A_ssb_3.html", + "source": "https://50ohm.de/NEA_ssb_3.html#AE205", "confidence": 8 }, "AE206": { - "revision": 1, + "revision": 2, "explanation": "A balanced mixer can cancel the carrier while leaving the two sidebands, producing a double-sideband suppressed-carrier signal for SSB generation.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AE206", "confidence": 8 }, "AE207": { - "revision": 1, + "revision": 2, "explanation": "A two-tone SSB test produces a characteristic varying RF envelope used to judge linearity and PEP; it is not a constant-envelope FM or simple CW trace.", - "source": "https://50ohm.de/A_ssb_3.html", + "source": "https://50ohm.de/NEA_ssb_3.html#AE207", "confidence": 7 }, "AE208": { - "revision": 1, + "revision": 2, "explanation": "The RF bandwidth of an SSB phone signal is approximately the bandwidth of the applied audio, so limiting speech audio to about 2.7 kHz keeps the SSB signal narrow.", - "source": "https://50ohm.de/A_ssb_3.html", + "source": "https://50ohm.de/NEA_ssb_3.html#AE208", "confidence": 8 }, "AE209": { - "revision": 1, - "explanation": "SSB phone is normally limited to about 2.7 kHz, so about 3 kHz spacing gives a small guard margin between adjacent SSB signals.", - "source": "https://50ohm.de/A_ssb_3.html", + "revision": 3, + "explanation": "SSB phone is normally limited to about 2.7 kHz, so about 3 kHz spacing gives a small guard margin between adjacent SSB signals. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ssb_3.html#AE209", "confidence": 8 }, "AE210": { - "revision": 1, + "revision": 2, "explanation": "An audio dynamic compressor reduces the difference between loud and quiet speech parts, so the modulation has a smaller dynamic range.", - "source": "https://50ohm.de/A_ssb_3.html", + "source": "https://50ohm.de/NEA_dynamik_compressor_2.html#AE210", "confidence": 8 }, "AE211": { - "revision": 1, + "revision": 2, "explanation": "By lifting quieter speech components and reducing dynamic range, compression raises the average SSB output power without requiring higher peaks when set correctly.", - "source": "https://50ohm.de/A_ssb_3.html", + "source": "https://50ohm.de/NEA_dynamik_compressor_2.html#AE211", "confidence": 8 }, "AE212": { - "revision": 1, + "revision": 2, "explanation": "Too much compression overprocesses the speech and can drive distortion/splatter, so the received audio becomes less intelligible rather than clearer.", - "source": "https://50ohm.de/A_ssb_3.html", + "source": "https://50ohm.de/NEA_dynamik_compressor_2.html#AE212", "confidence": 8 }, "AE213": { - "revision": 1, + "revision": 2, "explanation": "An equalizer shapes the microphone audio spectrum, letting the transmitter emphasize or reduce frequency ranges to suit the operator's voice.", - "source": "https://50ohm.de/A_ssb_3.html", + "source": "https://50ohm.de/NEA_ssb_3.html#AE213", "confidence": 8 }, "AE214": { - "revision": 1, + "revision": 2, "explanation": "Amplitude changes that are slower and less abrupt occupy less spectrum; the shown signal with the gentlest amplitude variation therefore has the smallest bandwidth.", - "source": "https://50ohm.de/NEA_symbolumschaltung_bandbreite.html", + "source": "https://50ohm.de/NEA_symbolumschaltung_bandbreite.html#AE214", "confidence": 7 }, "AE301": { - "revision": 2, + "revision": 3, "explanation": "In FM, the modulating signal frequency sets how often the RF carrier is moved back and forth. The modulation amplitude sets how far it moves; that frequency swing is called deviation, German Hub or Frequenzhub.", - "source": "https://50ohm.de/A_fm_3.html", + "source": "https://50ohm.de/NEA_fm_3.html#AE301", "confidence": 8 }, "AE302": { - "revision": 2, + "revision": 3, "explanation": "Impulse noise mainly changes amplitude. FM carries the information in frequency deviation, German Hub/Frequenzhub, so a limiter can remove much of the amplitude disturbance before the FM demodulator.", - "source": "https://50ohm.de/A_fm_3.html", + "source": "https://50ohm.de/NEA_fm_3.html#AE302", "confidence": 8 }, "AE303": { - "revision": 1, + "revision": 2, "explanation": "A varicap changes capacitance with the applied audio/control voltage; in an oscillator tank this shifts the oscillator frequency, producing FM.", - "source": "https://50ohm.de/A_fm_3.html", + "source": "https://50ohm.de/NEA_fm_3.html#AE303", "confidence": 8 }, "AE304": { - "revision": 2, + "revision": 3, "explanation": "Carson's rule estimates FM bandwidth as $B \\approx 2(\\Delta f + f_{mod,max})$. Here $\\Delta f$ is the deviation, German Hub/Frequenzhub. Higher audio frequency or larger Hub makes the RF bandwidth too large.", - "source": "https://50ohm.de/A_fm_3.html", + "source": "https://50ohm.de/NEA_fm_3.html#AE304", "confidence": 8 }, "AE305": { - "revision": 2, + "revision": 3, "explanation": "For FM speech, audio amplitude is represented by deviation, German Hub/Frequenzhub. A larger Hub means the carrier swings farther from centre, and after demodulation that corresponds to louder received audio.", - "source": "https://50ohm.de/A_fm_3.html", + "source": "https://50ohm.de/NEA_fm_3.html#AE305", "confidence": 8 }, "AE306": { - "revision": 2, + "revision": 3, "explanation": "Excessive FM deviation, German Hub/Frequenzhub, means the carrier swings too far from its centre frequency. That widens the transmitted spectrum and can spill into adjacent channels, causing interference.", - "source": "https://50ohm.de/A_fm_3.html", + "source": "https://50ohm.de/NEA_fm_3.html#AE306", "confidence": 8 }, "AE307": { - "revision": 2, + "revision": 3, "explanation": "Stronger FM modulator drive increases deviation, German Hub/Frequenzhub: the carrier swings farther away from centre. Larger Hub increases occupied RF bandwidth, so overdriving the modulator makes the signal too wide.", - "source": "https://50ohm.de/A_fm_3.html", + "source": "https://50ohm.de/NEA_fm_3.html#AE307", "confidence": 8 }, "AE308": { - "revision": 2, - "explanation": "Carson's rule gives $B \\approx 2(\\Delta f + f_{mod,max})$, where $\\Delta f$ is FM deviation, German Hub/Frequenzhub. With $\\Delta f=2.5 kHz$ and $f_{mod,max}=2.7 kHz$, $B=2(2.5+2.7)=10.4 kHz$.", - "source": "https://50ohm.de/A_fm_3.html", + "revision": 4, + "explanation": "Carson's rule gives $B \\approx 2(\\Delta f + f_{mod,max})$, where $\\Delta f$ is FM deviation, German Hub/Frequenzhub. With $\\Delta f=2.5 kHz$ and $f_{mod,max}=2.7 kHz$, $B=2(2.5+2.7)=10.4 kHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_fm_3.html#AE308", "confidence": 8 }, "AE309": { - "revision": 1, - "explanation": "Using Carson's rule, $B = 2 x (1.8 kHz + 2.0 kHz) = 7.6 kHz$; the 145 MHz carrier frequency does not enter this bandwidth estimate.", - "source": "https://50ohm.de/A_fm_3.html", + "revision": 3, + "explanation": "Using Carson's rule, $B = 2 x (1.8 kHz + 2.0 kHz) = 7.6 kHz$; the 145 MHz carrier frequency does not enter this bandwidth estimate. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_fm_3.html#AE309", "confidence": 8 }, "AE310": { - "revision": 2, - "explanation": "Narrowband FM in a 12.5 kHz channel uses a typical peak deviation, German Hub/Frequenzhub, of about 2.5 kHz. That leaves room for the modulation sidebands inside the channel spacing.", - "source": "https://50ohm.de/A_fm_3.html", + "revision": 4, + "explanation": "Narrowband FM in a 12.5 kHz channel uses a typical peak deviation, German Hub/Frequenzhub, of about 2.5 kHz. That leaves room for the modulation sidebands inside the channel spacing. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_fm_3.html#AE310", "confidence": 8 }, "AE311": { - "revision": 2, - "explanation": "Rearrange Carson's rule $B \\approx 2(\\Delta f + f_{mod})$. Here $\\Delta f$ is deviation, German Hub/Frequenzhub, so $f_{mod}=B/2-\\Delta f=10 kHz/2-2.5 kHz=2.5 kHz$.", - "source": "https://50ohm.de/A_fm_3.html", + "revision": 4, + "explanation": "Rearrange Carson's rule $B \\approx 2(\\Delta f + f_{mod})$. Here $\\Delta f$ is deviation, German Hub/Frequenzhub, so $f_{mod}=B/2-\\Delta f=10 kHz/2-2.5 kHz=2.5 kHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_fm_3.html#AE311", "confidence": 8 }, "AE312": { - "revision": 2, - "explanation": "Rearrange Carson's rule $B \\approx 2(\\Delta f + f_{mod})$. The deviation $\\Delta f$, German Hub/Frequenzhub, is $B/2-f_{mod}=10 kHz/2-2.7 kHz=2.3 kHz$.", - "source": "https://50ohm.de/A_fm_3.html", + "revision": 4, + "explanation": "Rearrange Carson's rule $B \\approx 2(\\Delta f + f_{mod})$. The deviation $\\Delta f$, German Hub/Frequenzhub, is $B/2-f_{mod}=10 kHz/2-2.7 kHz=2.3 kHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_fm_3.html#AE312", "confidence": 8 }, "AE313": { - "revision": 1, + "revision": 2, "explanation": "PM means phase modulation: the information signal changes the phase of the carrier rather than its amplitude or polarization.", - "source": "https://50ohm.de/EA_pm.html", + "source": "https://50ohm.de/NEA_pm.html#AE313", "confidence": 8 }, "AE401": { - "revision": 1, + "revision": 2, "explanation": "PSK keeps the carrier amplitude essentially constant but introduces abrupt phase changes; the correct trace is the one where the sine wave jumps phase rather than changing amplitude or frequency smoothly.", - "source": "https://50ohm.de/NEA_psk.html", + "source": "https://50ohm.de/NEA_psk.html#AE401", "confidence": 7 }, "AE402": { - "revision": 1, + "revision": 2, "explanation": "BPSK has two phase states, so each symbol carries one bit; QPSK has four phase states, so each symbol carries two bits.", - "source": "https://50ohm.de/A_mehrwertige_verfahren.html", + "source": "https://50ohm.de/NEA_mehrwertige_verfahren.html#AE402", "confidence": 8 }, "AE403": { - "revision": 1, + "revision": 2, "explanation": "QAM maps data onto combinations of carrier amplitude and carrier phase, giving more possible symbols than amplitude-only modulation.", - "source": "https://50ohm.de/A_qam.html", + "source": "https://50ohm.de/NEA_qam.html#AE403", "confidence": 8 }, "AE404": { - "revision": 1, + "revision": 2, "explanation": "QAM is commonly generated by amplitude-modulating two carriers that are 90 degrees apart, then adding them as I and Q components.", - "source": "https://50ohm.de/EA_iq_verfahren.html", + "source": "https://50ohm.de/NEA_iq_verfahren.html#AE404", "confidence": 8 }, "AE405": { - "revision": 1, + "revision": 2, "explanation": "With two symbol frequencies, each symbol represents one bit, so 45.45 baud corresponds directly to 45.45 bit/s.", - "source": "https://50ohm.de/A_mehrwertige_verfahren.html", + "source": "https://50ohm.de/NEA_mehrwertige_verfahren.html#AE405", "confidence": 8 }, "AE406": { - "revision": 1, + "revision": 2, "explanation": "Four symbol frequencies encode two bits per symbol; data rate is symbol rate times bits per symbol, so $23.4 x 2 = 46.8 bit/s$.", - "source": "https://50ohm.de/A_mehrwertige_verfahren.html", + "source": "https://50ohm.de/NEA_mehrwertige_verfahren.html#AE406", "confidence": 8 }, "AE407": { - "revision": 1, + "revision": 2, "explanation": "Synchronization means sender and receiver agree on timing, so the receiver knows where symbols or frames begin and can decode them correctly.", - "source": "https://50ohm.de/NEA_synchronisation.html", + "source": "https://50ohm.de/NEA_synchronisation.html#AE407", "confidence": 8 }, "AE408": { - "revision": 1, + "revision": 2, "explanation": "Source coding reduces the original message data, for example by removing redundancy or irrelevant information through compression.", - "source": "https://50ohm.de/NEA_quellencodierung.html", + "source": "https://50ohm.de/NEA_quellencodierung.html#AE408", "confidence": 8 }, "AE409": { - "revision": 1, + "revision": 2, "explanation": "Channel coding deliberately adds redundancy before transmission so the receiver can detect or correct errors caused by the channel.", - "source": "https://50ohm.de/NEA_kanalcodierung.html", + "source": "https://50ohm.de/NEA_kanalcodierung.html#AE409", "confidence": 8 }, "AE410": { - "revision": 1, + "revision": 2, "explanation": "CRC is a checksum-like error detection method for data blocks; it computes redundant check information from the block contents.", - "source": "https://50ohm.de/NEA_fehlererkennung.html", + "source": "https://50ohm.de/NEA_fehlererkennung.html#AE410", "confidence": 8 }, "AE411": { - "revision": 1, + "revision": 2, "explanation": "A single parity bit flips its check result when an odd number of bits is wrong; even numbers of bit errors preserve the parity and can pass undetected.", - "source": "https://50ohm.de/NEA_fehlererkennung.html", + "source": "https://50ohm.de/NEA_fehlererkennung.html#AE411", "confidence": 8 }, "AE412": { - "revision": 1, + "revision": 2, "explanation": "A passing parity check only proves the parity is unchanged; that can mean no error or an even number of bit errors including the parity bit.", - "source": "https://50ohm.de/NEA_fehlererkennung.html", + "source": "https://50ohm.de/NEA_fehlererkennung.html#AE412", "confidence": 8 }, "AE413": { - "revision": 1, + "revision": 2, "explanation": "Without FEC the receiver cannot reconstruct corrupted packet contents from redundancy, so correction requires requesting or receiving the packet again.", - "source": "https://50ohm.de/EA_fehlerkorrektur.html", + "source": "https://50ohm.de/NEA_fehlerkorrektur.html#AE413", "confidence": 8 }, "AE414": { - "revision": 1, + "revision": 2, "explanation": "Forward error correction needs redundant information in the transmitted data, so the receiver has enough extra checks to locate and correct errors.", - "source": "https://50ohm.de/EA_fehlerkorrektur.html", + "source": "https://50ohm.de/NEA_fehlerkorrektur.html#AE414", "confidence": 8 }, "AE415": { - "revision": 1, + "revision": 2, "explanation": "Faster symbol changes mean faster amplitude, frequency, or phase transitions, and faster transitions require a wider spectrum.", - "source": "https://50ohm.de/NEA_symbolumschaltung_bandbreite.html", + "source": "https://50ohm.de/NEA_symbolumschaltung_bandbreite.html#AE415", "confidence": 8 }, "AE416": { - "revision": 1, + "revision": 2, "explanation": "Shannon-Hartley gives the theoretical maximum error-free data rate for a channel from its bandwidth and signal-to-noise ratio.", - "source": "https://50ohm.de/A_shannon_hartley_gesetzt.html", + "source": "https://50ohm.de/NEA_shannon_hartley_gesetzt.html#AE416", "confidence": 8 }, "AE417": { - "revision": 1, + "revision": 2, "explanation": "At 0 dB SNR the linear SNR is 1, so $C = B x log2(1 + 1) = B$; 2.7 kHz therefore gives about 2.7 kbit/s.", - "source": "https://50ohm.de/A_shannon_hartley_gesetzt.html", + "source": "https://50ohm.de/NEA_shannon_hartley_gesetzt.html#AE417", "confidence": 8 }, "AE418": { - "revision": 1, + "revision": 2, "explanation": "At 0 dB SNR, Shannon-Hartley reduces to capacity approximately equal to bandwidth in bit/s, so 10 MHz gives about 10 Mbit/s.", - "source": "https://50ohm.de/A_shannon_hartley_gesetzt.html", + "source": "https://50ohm.de/NEA_shannon_hartley_gesetzt.html#AE418", "confidence": 8 }, "AE419": { - "revision": 1, + "revision": 2, "explanation": "30 dB SNR is a linear ratio of 1000, so capacity is $10 MHz x log2(1001)$, about $10 MHz x 10 = 100 Mbit/s$.", - "source": "https://50ohm.de/A_shannon_hartley_gesetzt.html", + "source": "https://50ohm.de/NEA_shannon_hartley_gesetzt.html#AE419", "confidence": 8 }, "AE420": { - "revision": 1, + "revision": 2, "explanation": "-20 dB SNR is a linear ratio of 0.01; $2700 x log2(1.01)$ is about 39 bit/s, so transmission is possible but very slow.", - "source": "https://50ohm.de/A_shannon_hartley_gesetzt.html", + "source": "https://50ohm.de/NEA_shannon_hartley_gesetzt.html#AE420", "confidence": 8 }, "AE421": { - "revision": 1, + "revision": 2, "explanation": "OFDM spreads data across many narrow subcarriers; a narrowband interferer damages only some carriers, and redundancy can recover the lost information.", - "source": "https://50ohm.de/EA_ofdm.html", + "source": "https://50ohm.de/NEA_ofdm.html#AE421", "confidence": 8 }, "AE422": { - "revision": 1, + "revision": 2, "explanation": "OFDM uses longer symbols on many subcarriers, so delayed copies from multipath overlap less destructively and can be handled better with redundant coding.", - "source": "https://50ohm.de/EA_ofdm.html", + "source": "https://50ohm.de/NEA_ofdm.html#AE422", "confidence": 8 }, "AF101": { - "revision": 1, + "revision": 2, "explanation": "Increasing power from 25 W to 100 W is a factor of 4, or +6 dB; one S-unit corresponds to 6 dB.", - "source": "https://50ohm.de/NEA_s_meter.html", + "source": "https://50ohm.de/NEA_s_meter.html#AF101", "confidence": 8 }, "AF102": { - "revision": 1, + "revision": 2, "explanation": "Increasing power from 100 W to 400 W is again a factor of 4, which is +6 dB, equal to one S-unit.", - "source": "https://50ohm.de/NEA_s_meter.html", + "source": "https://50ohm.de/NEA_s_meter.html#AF102", "confidence": 8 }, "AF103": { - "revision": 1, - "explanation": "A tenfold power increase is +10 dB. From S8, +6 dB reaches S9 and the remaining +4 dB gives S9+4 dB.", - "source": "https://50ohm.de/NEA_s_meter.html", + "revision": 3, + "explanation": "A tenfold power increase is +10 dB. From S8, +6 dB reaches S9 and the remaining +4 dB gives S9+4 dB. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_s_meter.html#AF103", "confidence": 8 }, "AF104": { - "revision": 1, + "revision": 2, "explanation": "S7 to S9 is two S-units, or 12 dB; S9+8 dB makes the total increase 20 dB, which is a 100-fold power ratio.", - "source": "https://50ohm.de/NEA_s_meter.html", + "source": "https://50ohm.de/NEA_s_meter.html#AF104", "confidence": 8 }, "AF105": { - "revision": 1, + "revision": 2, "explanation": "One S-unit lower is -6 dB in voltage, i.e. half the input voltage; half of 50 microvolt is 25 microvolt.", - "source": "https://50ohm.de/NEA_s_meter.html", + "source": "https://50ohm.de/NEA_s_meter.html#AF105", "confidence": 8 }, "AF106": { - "revision": 1, + "revision": 2, "explanation": "In a simple superhet, the wanted signal and its image are on opposite sides of the local oscillator by one IF each, so their separation is twice the IF.", - "source": "https://50ohm.de/EA_spiegelfrequenzen.html", + "source": "https://50ohm.de/NEA_spiegelfrequenzen.html#AF106", "confidence": 8 }, "AF107": { - "revision": 1, - "explanation": "The IF is $24.94 MHz - 14.24 MHz = 10.70 MHz$; the image on the other side of the oscillator is $24.94 MHz + 10.70 MHz = 35.64 MHz$.", - "source": "https://50ohm.de/EA_spiegelfrequenzen.html", + "revision": 3, + "explanation": "The IF is $24.94 MHz - 14.24 MHz = 10.70 MHz$; the image on the other side of the oscillator is $24.94 MHz + 10.70 MHz = 35.64 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spiegelfrequenzen.html#AF107", "confidence": 7 }, "AF108": { - "revision": 1, - "explanation": "With high-side injection the oscillator is $28.5 MHz + 10.7 MHz = 39.2 MHz$; the image is another IF above that, $39.2 MHz + 10.7 MHz = 49.9 MHz$.", - "source": "https://50ohm.de/EA_spiegelfrequenzen.html", + "revision": 3, + "explanation": "With high-side injection the oscillator is $28.5 MHz + 10.7 MHz = 39.2 MHz$; the image is another IF above that, $39.2 MHz + 10.7 MHz = 49.9 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spiegelfrequenzen.html#AF108", "confidence": 7 }, "AF109": { - "revision": 1, + "revision": 2, "explanation": "A very high first IF moves the image by twice that IF, placing the image far away from the wanted HF band where RF filtering can reject it more easily.", - "source": "https://50ohm.de/A_ueberlagerungsempfaenger_einfachsuper_2.html", + "source": "https://50ohm.de/NEA_spiegelfrequenzen.html#AF109", "confidence": 8 }, "AF110": { - "revision": 1, + "revision": 2, "explanation": "Image frequency separation is twice the IF, so the IF value mainly determines how far the image is from the wanted frequency and how easily it can be filtered.", - "source": "https://50ohm.de/EA_spiegelfrequenzen.html", + "source": "https://50ohm.de/NEA_spiegelfrequenzen.html#AF110", "confidence": 8 }, "AF111": { - "revision": 1, + "revision": 2, "explanation": "A high first IF gives a large spacing between wanted and image frequencies, improving image-frequency rejection before the mixer.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_spiegelfrequenzen.html#AF111", "confidence": 8 }, "AF112": { - "revision": 1, + "revision": 2, "explanation": "In a double superhet, the high first IF is chosen mainly for image rejection, while later lower IF stages can provide selectivity.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_doppelueberlagerungsempfaenger_doppelsuper.html#AF112", "confidence": 8 }, "AF113": { - "revision": 1, + "revision": 2, "explanation": "A low second IF allows narrow, high-selectivity filters, so it is useful for good adjacent-signal separation.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_doppelueberlagerungsempfaenger_doppelsuper.html#AF113", "confidence": 8 }, "AF114": { - "revision": 1, + "revision": 2, "explanation": "The high first IF helps image rejection; after roofing-filter preselection, conversion to a lower second IF makes narrow filtering and selectivity easier.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_doppelueberlagerungsempfaenger_doppelsuper.html#AF114", "confidence": 8 }, "AF115": { - "revision": 1, + "revision": 2, "explanation": "Near selectivity is the ability to separate nearby signals, and that is set by the receiver's IF filters rather than by RF gain stages.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_ueberlagerungsempfaenger_einfachsuper_2.html#AF115", "confidence": 8 }, "AF116": { - "revision": 1, + "revision": 2, "explanation": "The first IF filter must not cut off any intended mode, so its bandwidth must be at least as wide as the widest receive mode the receiver is meant to handle.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_doppelueberlagerungsempfaenger_doppelsuper.html#AF116", "confidence": 8 }, "AF117": { - "revision": 1, + "revision": 2, "explanation": "The first mixer is driven by the tunable VFO, the second conversion by a fixed crystal oscillator, and the final product detector needs the BFO to recover SSB/CW audio.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_doppelueberlagerungsempfaenger_doppelsuper.html#AF117", "confidence": 7 }, "AF118": { - "revision": 1, + "revision": 2, "explanation": "High-side first conversion needs $21.1 MHz + 9 MHz = 30.1 MHz$ for the VFO; low-side conversion from 9 MHz to 460 kHz needs $9 MHz - 0.460 MHz = 8.54 MHz$ for the CO.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_doppelueberlagerungsempfaenger_doppelsuper.html#AF118", "confidence": 7 }, "AF119": { - "revision": 1, + "revision": 2, "explanation": "With both oscillators above their input signals, the VFO is $28.00 MHz + 10.70 MHz = 38.70 MHz$ and the second oscillator is $10.70 MHz + 0.460 MHz = 11.16 MHz$.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_doppelueberlagerungsempfaenger_doppelsuper.html#AF119", "confidence": 7 }, "AF120": { - "revision": 1, + "revision": 2, "explanation": "The chain can mix $3.65 MHz + 46.35 MHz$ to a 50 MHz first IF, then $50 MHz - 41 MHz$ to 9 MHz, then $9.455 MHz - 9 MHz$ to 455 kHz.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_doppelueberlagerungsempfaenger_doppelsuper.html#AF120", "confidence": 7 }, "AF201": { - "revision": 1, + "revision": 2, "explanation": "The wanted signal and image produce the same IF on opposite sides of the local oscillator, so their frequency spacing is twice the IF.", - "source": "https://50ohm.de/A_spiegelfrequenzen.html", + "source": "https://50ohm.de/NEA_spiegelfrequenzen.html#AF201", "confidence": 7 }, "AF202": { - "revision": 1, - "explanation": "The IF is $145.6 MHz - 134.9 MHz = 10.7 MHz$; the image is the other signal 10.7 MHz from the oscillator, $134.9 MHz - 10.7 MHz = 124.2 MHz$.", - "source": "https://50ohm.de/A_spiegelfrequenzen.html", + "revision": 3, + "explanation": "The IF is $145.6 MHz - 134.9 MHz = 10.7 MHz$; the image is the other signal 10.7 MHz from the oscillator, $134.9 MHz - 10.7 MHz = 124.2 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spiegelfrequenzen.html#AF202", "confidence": 7 }, "AF203": { - "revision": 1, - "explanation": "The image is mirrored around the oscillator frequency: $2 x 39 MHz - 28.3 MHz = 49.7 MHz$.", - "source": "https://50ohm.de/A_spiegelfrequenzen.html", + "revision": 3, + "explanation": "The image is mirrored around the oscillator frequency: $2 x 39 MHz - 28.3 MHz = 49.7 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spiegelfrequenzen.html#AF203", "confidence": 8 }, "AF204": { - "revision": 1, + "revision": 2, "explanation": "Image rejection must happen before the mixer, because the wanted signal and image become the same IF after mixing; therefore RF preselection determines image attenuation.", - "source": "https://50ohm.de/A_spiegelfrequenzen.html", + "source": "https://50ohm.de/NEA_spiegelfrequenzen.html#AF204", "confidence": 8 }, "AF205": { - "revision": 1, + "revision": 2, "explanation": "Receiver selectivity is set by the IF filters, because nearby signals are separated after conversion to the fixed intermediate frequency.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_trennschaerfe_2.html#AF205", "confidence": 8 }, "AF206": { - "revision": 1, + "revision": 2, "explanation": "Typical receiver IF bandwidths match the mode: about 2.7 kHz for SSB speech, about 500 Hz for narrow RTTY/CW-like signals, and about 12 kHz for FM speech.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_trennschaerfe_2.html#AF206", "confidence": 8 }, "AF207": { - "revision": 1, + "revision": 2, "explanation": "The shown narrow passband is around the audio bandwidth used for SSB, much narrower than FM and not shaped for wide digital OFDM.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_trennschaerfe_2.html#AF207", "confidence": 7 }, "AF208": { - "revision": 1, + "revision": 2, "explanation": "Crystal filters can have very high Q and steep skirts, so they are best suited for narrow IF bandwidths at a given center frequency.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_trennschaerfe_2.html#AF208", "confidence": 8 }, "AF209": { - "revision": 1, + "revision": 2, "explanation": "In a double superhet, the first two conversion blocks are mixers, and the final block before audio is a product detector for SSB/CW demodulation.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "source": "https://50ohm.de/NEA_doppelueberlagerungsempfaenger_doppelsuper.html#AF209", "confidence": 7 }, "AF210": { - "revision": 1, - "explanation": "For a 50 MHz first IF and a 3 to 30 MHz receive range, the VFO can use either difference mixing $50 - f_rx$ = 47 to 20 MHz or sum mixing $50 + f_rx$ = 53 to 80 MHz.", - "source": "https://50ohm.de/A_doppelueberlagerungsempfaenger_doppelsuper.html", + "revision": 3, + "explanation": "For a 50 MHz first IF and a 3 to 30 MHz receive range, the VFO can use either difference mixing $50 - f_rx$ = 47 to 20 MHz or sum mixing $50 + f_rx$ = 53 to 80 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_doppelueberlagerungsempfaenger_doppelsuper.html#AF210", "confidence": 7 }, "AF211": { - "revision": 1, - "explanation": "For CW, the BFO is offset from the last IF by an audible tone frequency; about 800 Hz gives a comfortable received beat note.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "revision": 3, + "explanation": "For CW, the BFO is offset from the last IF by an audible tone frequency; about 800 Hz gives a comfortable received beat note. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_bfo_2.html#AF211", "confidence": 8 }, "AF212": { - "revision": 1, + "revision": 2, "explanation": "A mixer must be nonlinear so it creates sum and difference products from the input and local oscillator frequencies.", - "source": "https://50ohm.de/A_mischer_2.html", + "source": "https://50ohm.de/NEA_mischer_2.html#AF212", "confidence": 8 }, "AF213": { - "revision": 1, + "revision": 2, "explanation": "A balanced mixer cancels some unwanted components such as carrier/oscillator feedthrough, so fewer unwanted output signals remain than with simple unbalanced mixers.", - "source": "https://50ohm.de/A_mischer_2.html", + "source": "https://50ohm.de/NEA_mischer_2.html#AF213", "confidence": 8 }, "AF214": { - "revision": 1, + "revision": 2, "explanation": "A balanced ring mixer has strong symmetry, which suppresses unwanted feedthrough and many unwanted mixer products better than simple unbalanced mixer circuits.", - "source": "https://50ohm.de/A_mischer_2.html", + "source": "https://50ohm.de/NEA_mischer_2.html#AF214", "confidence": 8 }, "AF215": { - "revision": 1, + "revision": 2, "explanation": "Even a temperature-compensated VFO can drift if heated unevenly, so it should be thermally isolated from power stages and other heat sources.", - "source": "https://50ohm.de/A_oszillator_tcxo_ocxo.html", + "source": "https://50ohm.de/NEA_oszillator_tcxo_ocxo.html#AF215", "confidence": 8 }, "AF216": { - "revision": 1, + "revision": 2, "explanation": "An SSB BFO must be frequency-stable because its frequency defines the reinserted carrier position; a crystal-controlled oscillator is the stable choice.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_bfo_2.html#AF216", "confidence": 8 }, "AF217": { - "revision": 1, + "revision": 2, "explanation": "Two signals in a nonlinear receiver stage generate sum, difference, and higher-order products; that phenomenon is intermodulation.", - "source": "https://50ohm.de/A_intermodulation_kreuzmodulation.html", + "source": "https://50ohm.de/NEA_intermodulation_kreuzmodulation.html#AF217", "confidence": 8 }, "AF218": { - "revision": 1, + "revision": 2, "explanation": "Intermodulation is caused by nonlinearity: strong input signals push the RF stage out of its linear range and create extra frequency products.", - "source": "https://50ohm.de/A_intermodulation_kreuzmodulation.html", + "source": "https://50ohm.de/NEA_intermodulation_kreuzmodulation.html#AF218", "confidence": 8 }, "AF219": { - "revision": 1, + "revision": 2, "explanation": "Cross modulation occurs when a strong unwanted signal affects the receiver stage and transfers its modulation onto the desired signal.", - "source": "https://50ohm.de/A_intermodulation_kreuzmodulation.html", + "source": "https://50ohm.de/NEA_intermodulation_kreuzmodulation.html#AF219", "confidence": 8 }, "AF220": { - "revision": 1, + "revision": 2, "explanation": "An input attenuator reduces the level of all incoming strong signals, keeping the receiver front end more linear and reducing intermodulation and cross modulation.", - "source": "https://50ohm.de/A_intermodulation_kreuzmodulation.html", + "source": "https://50ohm.de/NEA_intermodulation_kreuzmodulation.html#AF220", "confidence": 8 }, "AF221": { - "revision": 1, - "explanation": "IP3 is a measure of third-order intermodulation behavior, so it indicates how well the receiver handles large signals without generating distortion products.", - "source": "https://50ohm.de/A_intermodulation_kreuzmodulation.html", + "revision": 2, + "explanation": "IP3 is a measure of third-order intermodulation behavior, so it indicates how well the receiver handles large signals without generating distortion products. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_intermodulation_kreuzmodulation.html#AF221", "confidence": 8 }, "AF222": { - "revision": 1, + "revision": 2, "explanation": "A strong nearby RF signal can overload or desensitize receiver stages, producing intermodulation or cross modulation that degrades the wanted signal.", - "source": "https://50ohm.de/A_intermodulation_kreuzmodulation.html", + "source": "https://50ohm.de/NEA_intermodulation_kreuzmodulation.html#AF222", "confidence": 8 }, "AF223": { - "revision": 1, + "revision": 2, "explanation": "A notch or trap tuned to the unwanted signal at the receiver input can reject that interferer before it reaches the sensitive front end.", - "source": "https://50ohm.de/A_intermodulation_kreuzmodulation.html", + "source": "https://50ohm.de/NEA_intermodulation_kreuzmodulation.html#AF223", "confidence": 7 }, "AF224": { - "revision": 1, + "revision": 2, "explanation": "AGC keeps receiver output level more constant; for strong input signals it reduces gain in receiver amplifier stages.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_agc_2.html#AF224", "confidence": 8 }, "AF225": { - "revision": 1, + "revision": 2, "explanation": "Squelch decides whether useful modulation or carrier/noise is present by evaluating IF or audio-derived signals, then mutes or unmutes the receiver audio.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_squelch_2.html#AF225", "confidence": 8 }, "AF226": { - "revision": 2, + "revision": 3, "explanation": "In FM, information is in frequency deviation, German Hub/Frequenzhub, not in RF amplitude. A limiter can therefore remove amplitude variations and suppress AM noise before the FM demodulator recovers the audio.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_begrenzerverstaerker.html#AF226", "confidence": 8 }, "AF227": { - "revision": 1, + "revision": 2, "explanation": "SNR is the ratio of wanted signal power to noise power; a higher SNR means the wanted signal stands out more clearly from noise.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_snr_rauschzahl.html#AF227", "confidence": 8 }, "AF228": { - "revision": 1, + "revision": 2, "explanation": "Noise figure in dB states how much the amplifier worsens SNR; 1.8 dB means the output SNR is 1.8 dB lower than the input SNR.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_snr_rauschzahl.html#AF228", "confidence": 8 }, "AF229": { - "revision": 1, + "revision": 2, "explanation": "A noise factor of 2 corresponds to $10 log10(2) = 3 dB$, meaning the amplifier degrades the signal-to-noise ratio by 3 dB.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_snr_rauschzahl.html#AF229", "confidence": 8 }, "AF230": { - "revision": 1, + "revision": 2, "explanation": "The LNB amplifies the weak microwave signal at the antenna and converts it to a lower IF, so the long coax no longer carries the original 10 GHz signal with its high cable loss.", - "source": "https://50ohm.de/A_low_noise_block.html", + "source": "https://50ohm.de/NEA_low_noise_block.html#AF230", "confidence": 7 }, "AF231": { - "revision": 1, + "revision": 2, "explanation": "Satellite LNBs commonly use different supply voltages to select polarization; raising the Bias-T supply to 18 V commands a polarization change.", - "source": "https://50ohm.de/A_low_noise_block.html", + "source": "https://50ohm.de/NEA_low_noise_block.html#AF231", "confidence": 7 }, "AF301": { - "revision": 1, + "revision": 2, "explanation": "A mixer can add the 5.3 MHz signal and a 9 MHz oscillator to produce 14.3 MHz; a bandfilter then selects that desired product.", - "source": "https://50ohm.de/A_transverter_2.html", + "source": "https://50ohm.de/NEA_transverter_2.html#AF301", "confidence": 8 }, "AF302": { - "revision": 1, + "revision": 2, "explanation": "A balanced mixer/modulator suppresses the carrier by symmetry while leaving the two sidebands, producing DSB with suppressed carrier.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AF302", "confidence": 8 }, "AF303": { - "revision": 1, + "revision": 2, "explanation": "The usual analog SSB chain first creates DSB with a balanced modulator, then a sideband filter passes only one of the two sidebands.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AF303", "confidence": 8 }, "AF304": { - "revision": 1, + "revision": 2, "explanation": "Analog SSB generation suppresses the carrier in the balanced modulator and removes the unwanted sideband with a filter.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AF304", "confidence": 8 }, "AF305": { - "revision": 1, - "explanation": "After the balanced modulator has made DSB, the marked filter must be a narrow bandpass, commonly a crystal filter, that selects the desired sideband.", - "source": "https://50ohm.de/A_modulatoren.html", + "revision": 2, + "explanation": "After the balanced modulator has made DSB, the marked filter must be a narrow bandpass, commonly a crystal filter, that selects the desired sideband. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_modulatoren.html#AF305", "confidence": 7 }, "AF306": { - "revision": 1, + "revision": 2, "explanation": "The block after the audio amplifier multiplies the audio with the carrier oscillator; in an SSB transmitter that function is the balanced mixer/modulator.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AF306", "confidence": 7 }, "AF307": { - "revision": 1, - "explanation": "The USB carrier frequency is symmetric to the LSB carrier around the 9 MHz filter center: $9.0000 MHz - (9.0015 - 9.0000) MHz = 8.9985 MHz$.", - "source": "https://50ohm.de/A_modulatoren.html", + "revision": 3, + "explanation": "The USB carrier frequency is symmetric to the LSB carrier around the 9 MHz filter center: $9.0000 MHz - (9.0015 - 9.0000) MHz = 8.9985 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_modulatoren.html#AF307", "confidence": 7 }, "AF308": { - "revision": 1, + "revision": 2, "explanation": "The balanced diode modulator cancels the carrier and leaves the modulation sidebands, so it generates AM with suppressed carrier.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AF308", "confidence": 7 }, "AF309": { - "revision": 1, - "explanation": "The balancing network trims amplitude and phase so the carrier components cancel as well as possible in the balanced modulator.", - "source": "https://50ohm.de/A_modulatoren.html", + "revision": 2, + "explanation": "The balancing network trims amplitude and phase so the carrier components cancel as well as possible in the balanced modulator. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_modulatoren.html#AF309", "confidence": 7 }, "AF310": { - "revision": 1, + "revision": 2, "explanation": "The diode is a varicap in the oscillator tank; the audio voltage changes its capacitance, shifting the resonant frequency and producing FM.", - "source": "https://50ohm.de/A_modulatoren.html", + "source": "https://50ohm.de/NEA_modulatoren.html#AF310", "confidence": 7 }, "AF311": { - "revision": 1, + "revision": 2, "explanation": "Analog frequency multiplication deliberately drives a nonlinear stage to create harmonics, then filters out the desired harmonic frequency.", - "source": "https://50ohm.de/A_frequenzvervielfacher_2.html", + "source": "https://50ohm.de/NEA_frequenzvervielfacher_2.html#AF311", "confidence": 8 }, "AF312": { - "revision": 1, + "revision": 2, "explanation": "The stage is biased and tuned to use distortion harmonics rather than linear amplification, which identifies it as a frequency multiplier.", - "source": "https://50ohm.de/A_frequenzvervielfacher_2.html", + "source": "https://50ohm.de/NEA_frequenzvervielfacher_2.html#AF312", "confidence": 7 }, "AF313": { - "revision": 1, + "revision": 2, "explanation": "Frequency multipliers intentionally generate harmonics, including unwanted ones, so shielding is important to prevent those signals from being radiated.", - "source": "https://50ohm.de/A_frequenzvervielfacher_2.html", + "source": "https://50ohm.de/NEA_frequenzvervielfacher_2.html#AF313", "confidence": 8 }, "AF314": { - "revision": 1, - "explanation": "Only the sequence $12 MHz x 2 x 2 x 3 x 3$ passes through 144 MHz as an intermediate result: 24 MHz, 48 MHz, 144 MHz, then 432 MHz.", - "source": "https://50ohm.de/A_frequenzvervielfacher_2.html", + "revision": 2, + "explanation": "Only the sequence $12 MHz x 2 x 2 x 3 x 3$ passes through 144 MHz as an intermediate result: 24 MHz, 48 MHz, 144 MHz, then 432 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzvervielfacher_2.html#AF314", "confidence": 8 }, "AF401": { - "revision": 1, + "revision": 2, "explanation": "HF amplifier efficiency is useful RF output power divided by the DC power taken from the supply.", - "source": "https://50ohm.de/A_verstaerker_wirkungsgrad.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF401", "confidence": 8 }, "AF402": { - "revision": 1, + "revision": 2, "explanation": "Class C conducts for less than half the RF cycle, making it highly nonlinear and therefore rich in harmonics.", - "source": "https://50ohm.de/A_verstaerker_klasse.html", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AF402", "confidence": 8 }, "AF403": { - "revision": 1, + "revision": 2, "explanation": "Class C stages and their output networks can contain strong harmonics, so the matching and filtering circuits should be enclosed in a shielded metal housing.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AF403", "confidence": 8 }, "AF404": { - "revision": 1, + "revision": 2, "explanation": "An LC output network transforms the PA output impedance to the antenna impedance and, because it is frequency-selective, also attenuates harmonics.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF404", "confidence": 8 }, "AF405": { - "revision": 1, + "revision": 2, "explanation": "A pi output filter acts as an impedance transformer and a low-pass network, so it improves matching while suppressing harmonics.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF405", "confidence": 8 }, "AF406": { - "revision": 1, + "revision": 2, "explanation": "The marked output network is the matching section; it transforms the external load impedance to the impedance the transistor stage needs.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF406", "confidence": 7 }, "AF407": { - "revision": 1, + "revision": 2, "explanation": "The marked input matching parts transform the previous stage's output impedance to the transistor's required input impedance for proper drive.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF407", "confidence": 7 }, "AF408": { - "revision": 1, + "revision": 2, "explanation": "The tuned resonant circuits in the RF signal path make the stage frequency-selective, so it is a selective RF amplifier rather than a broadband or audio amplifier.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF408", "confidence": 7 }, "AF409": { - "revision": 1, + "revision": 2, "explanation": "A tapped resonant circuit can provide impedance transformation, letting the preceding stage drive the tuned amplifier input at a suitable impedance point.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF409", "confidence": 7 }, "AF410": { - "revision": 1, - "explanation": "C1 and C2 are part of the matching network, setting the impedance transformation between the transistor stage and the connected circuit.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "C1 and C2 are part of the matching network, setting the impedance transformation between the transistor stage and the connected circuit. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF410", "confidence": 7 }, "AF411": { - "revision": 1, + "revision": 2, "explanation": "The marked supply decoupling path gives RF a low-impedance route to ground, preventing RF from entering the DC supply line.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF411", "confidence": 7 }, "AF412": { - "revision": 1, + "revision": 2, "explanation": "The push-pull transformer-coupled layout is intended for broadband RF amplification rather than a narrow tuned stage, so it is a broadband push-pull amplifier.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF412", "confidence": 7 }, "AF413": { - "revision": 1, + "revision": 2, "explanation": "The two cascaded broadband transformer-coupled stages identify the circuit as a two-stage broadband RF amplifier.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF413", "confidence": 7 }, "AF414": { - "revision": 1, - "explanation": "The transformer couples stages while transforming the output impedance of one emitter stage to the input impedance of the following emitter stage.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "The transformer couples stages while transforming the output impedance of one emitter stage to the input impedance of the following emitter stage. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF414", "confidence": 7 }, "AF415": { - "revision": 1, - "explanation": "Large capacitors are effective at low frequencies but poorer at very high RF; small capacitors keep low impedance at high frequencies, so the parallel pair decouples over a wider range.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "Large capacitors are effective at low frequencies but poorer at very high RF; small capacitors keep low impedance at high frequencies, so the parallel pair decouples over a wider range. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF415", "confidence": 7 }, "AF416": { - "revision": 1, - "explanation": "The resistor damps the transformer winding, reducing excessive Q and helping prevent parasitic oscillations.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "The resistor damps the transformer winding, reducing excessive Q and helping prevent parasitic oscillations. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_parasitaere_schwingungen.html#AF416", "confidence": 7 }, "AF417": { - "revision": 1, - "explanation": "The transformers provide broadband impedance transformation between the 50 ohm system and the low transistor input and output impedances.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "The transformers provide broadband impedance transformation between the 50 ohm system and the low transistor input and output impedances. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF417", "confidence": 7 }, "AF418": { - "revision": 1, - "explanation": "An inductor in series with shunt capacitors forms an LC low-pass section: it passes DC/low-frequency supply current but diverts RF to ground.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "An inductor in series with shunt capacitors forms an LC low-pass section: it passes DC/low-frequency supply current but diverts RF to ground. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF418", "confidence": 7 }, "AF419": { - "revision": 1, - "explanation": "The choke and bypass capacitors form supply-line filtering, reducing RF components on the DC supply line rather than filtering the transmitted RF path itself.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "The choke and bypass capacitors form supply-line filtering, reducing RF components on the DC supply line rather than filtering the transmitted RF path itself. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF419", "confidence": 7 }, "AF420": { - "revision": 1, - "explanation": "Moving R3 toward position 3 lowers the gate bias for both LDMOS devices in the DC equivalent circuit, so both drain currents decrease.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "Moving R3 toward position 3 lowers the gate bias for both LDMOS devices in the DC equivalent circuit, so both drain currents decrease. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF420", "confidence": 7 }, "AF421": { - "revision": 1, - "explanation": "For DC bias, the gates draw negligible current and the resistor network acts as a voltage divider; at stop 1 the divider sets the gate-source voltage to 3.5 V.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "For DC bias, the gates draw negligible current and the resistor network acts as a voltage divider; at stop 1 the divider sets the gate-source voltage to 3.5 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF421", "confidence": 7 }, "AF422": { - "revision": 1, + "revision": 2, "explanation": "The coils are RF chokes in the supply feeds; they pass DC but present high impedance to RF, keeping RF out of the supply line.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF422", "confidence": 7 }, "AF423": { - "revision": 1, - "explanation": "Increasing LDMOS quiescent current means raising both gate-bias voltages, so both bias controls are moved toward UBIAS.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "Increasing LDMOS quiescent current means raising both gate-bias voltages, so both bias controls are moved toward UBIAS. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF423", "confidence": 7 }, "AF424": { - "revision": 1, - "explanation": "R4 affects only the bias path for transistor 1 in the shown circuit; moving its wiper toward UBIAS raises that gate bias and drain current, while transistor 2 is unchanged.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 2, + "explanation": "R4 affects only the bias path for transistor 1 in the shown circuit; moving its wiper toward UBIAS raises that gate bias and drain current, while transistor 2 is unchanged. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF424", "confidence": 7 }, "AF425": { - "revision": 1, - "explanation": "The resistor must drop $13.5 V - 4 V = 9.5 V$ at 10 mA, so $R = 9.5 V / 0.010 A = 950 ohm$.", - "source": "https://50ohm.de/A_integrierte_schaltkreise.html", + "revision": 2, + "explanation": "The resistor must drop $13.5 V - 4 V = 9.5 V$ at 10 mA, so $R = 9.5 V / 0.010 A = 950 ohm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_integrierte_schaltkreise.html#AF425", "confidence": 7 }, "AF426": { - "revision": 1, - "explanation": "The bias resistor drops $13.8 V - 4 V = 9.8 V$ at 15 mA; $9.8 V / 0.015 A = 653 ohm$, so the nearest listed standard value is 680 ohm.", - "source": "https://50ohm.de/A_integrierte_schaltkreise.html", + "revision": 2, + "explanation": "The bias resistor drops $13.8 V - 4 V = 9.8 V$ at 15 mA; $9.8 V / 0.015 A = 653 ohm$, so the nearest listed standard value is 680 ohm. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_integrierte_schaltkreise.html#AF426", "confidence": 7 }, "AF427": { - "revision": 1, - "explanation": "With a 4 V MMIC drop, the resistor current is $(9 V - 4 V) / 470 ohm = 10.6 mA$; MMIC heat is $4 V x 10.6 mA = 42.6 mW$, about 43 mW.", - "source": "https://50ohm.de/A_integrierte_schaltkreise.html", + "revision": 2, + "explanation": "With a 4 V MMIC drop, the resistor current is $(9 V - 4 V) / 470 ohm = 10.6 mA$; MMIC heat is $4 V x 10.6 mA = 42.6 mW$, about 43 mW. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_integrierte_schaltkreise.html#AF427", "confidence": 7 }, "AF428": { - "revision": 1, - "explanation": "Overall gain in dB is the output level minus the input level in dBm; the diagram's level difference is 48 dB when cable losses are ignored.", - "source": "https://50ohm.de/NEA_leistungsvertaerker.html", + "revision": 3, + "explanation": "Overall gain in dB is the output level minus the input level in dBm; the diagram's level difference is 48 dB when cable losses are ignored. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistungsvertaerker.html#AF428", "confidence": 7 }, "AF501": { - "revision": 1, - "explanation": "The converter uses the 9th harmonic of the crystal oscillator and maps the 436 to 440 MHz range to 28 to 30 MHz, so $f_Q = (f_rx - f_IF) / 9$ gives 45.333 MHz and 45.556 MHz.", - "source": "https://50ohm.de/A_transverter_2.html", + "revision": 2, + "explanation": "The converter uses the 9th harmonic of the crystal oscillator and maps the 436 to 440 MHz range to 28 to 30 MHz, so $f_Q = (f_rx - f_IF) / 9$ gives 45.333 MHz and 45.556 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transverter_2.html#AF501", "confidence": 7 }, "AF502": { - "revision": 1, - "explanation": "For the lower 70 cm segment, the same conversion maps 430 to 434 MHz down to 28 to 30 MHz using the 9th harmonic, so $(430 - 28) / 9 = 44.667 MHz$ and $(434 - 30) / 9 = 44.889 MHz$.", - "source": "https://50ohm.de/A_transverter_2.html", + "revision": 2, + "explanation": "For the lower 70 cm segment, the same conversion maps 430 to 434 MHz down to 28 to 30 MHz using the 9th harmonic, so $(430 - 28) / 9 = 44.667 MHz$ and $(434 - 30) / 9 = 44.889 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transverter_2.html#AF502", "confidence": 7 }, "AF601": { - "revision": 1, + "revision": 2, "explanation": "A continuous analog waveform is uninterrupted in time and amplitude, so it is both time-continuous and value-continuous.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_sampling_quantisierung.html#AF601", "confidence": 8 }, "AF602": { - "revision": 1, + "revision": 2, "explanation": "Time stays continuous when the curve is drawn without sample instants, but quantized amplitude levels make the value axis discrete.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_sampling_quantisierung.html#AF602", "confidence": 8 }, "AF603": { - "revision": 1, + "revision": 2, "explanation": "Sampling selects separate instants in time; if the samples can still take arbitrary amplitudes, only the time axis is discrete.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_sampling_quantisierung.html#AF603", "confidence": 8 }, "AF604": { - "revision": 1, + "revision": 2, "explanation": "A digital sample stream is discrete twice: samples occur at fixed instants and each sample is rounded to one of the available amplitude codes.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_sampling_quantisierung.html#AF604", "confidence": 8 }, "AF605": { - "revision": 1, + "revision": 2, "explanation": "Quantization maps a continuous amplitude range onto a finite set of amplitude levels.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_quantisierung.html#AF605", "confidence": 8 }, "AF606": { - "revision": 1, + "revision": 2, "explanation": "Sampling is the time operation: a continuous signal is observed at discrete time instants.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_sampling.html#AF606", "confidence": 8 }, "AF607": { - "revision": 1, + "revision": 2, "explanation": "An A/D converter has only finitely many output codes, so most input voltages must be rounded to the nearest code and a quantization error remains.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_analog_digital_umsetzer.html#AF607", "confidence": 8 }, "AF608": { - "revision": 1, + "revision": 2, "explanation": "An 8-bit converter has $2^8 = 256$ possible codes, so it can separate at most 256 input ranges.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_analog_digital_umsetzer.html#AF608", "confidence": 8 }, "AF609": { - "revision": 1, + "revision": 2, "explanation": "Ten digital bits give $2^{10} = 1024$ different output codes or voltage steps.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_digital_analog_umsetzer.html#AF609", "confidence": 8 }, "AF610": { - "revision": 1, - "explanation": "Eight bits give 256 steps across 1 V; $1 V / 256$ is about 3.9 mV.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "revision": 3, + "explanation": "Eight bits give 256 steps across 1 V; $1 V / 256$ is about 3.9 mV. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_digital_analog_umsetzer.html#AF610", "confidence": 8 }, "AF611": { - "revision": 1, - "explanation": "Ten bits give 1024 steps across 1 V; $1 V / 1024$ is about 0.98 mV.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "revision": 3, + "explanation": "Ten bits give 1024 steps across 1 V; $1 V / 1024$ is about 0.98 mV. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_digital_analog_umsetzer.html#AF611", "confidence": 8 }, "AF612": { - "revision": 1, + "revision": 2, "explanation": "With only 4 bits the sine stays within range but is represented by coarse voltage steps, so the output is visibly stair-stepped.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_anwendung_dac_adc.html#AF612", "confidence": 8 }, "AF613": { - "revision": 1, + "revision": 2, "explanation": "A 12-bit converter over +/-2 V has enough range for a 1.5 V peak sine and fine quantization, so the reconstructed output closely follows the input.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_anwendung_dac_adc.html#AF613", "confidence": 8 }, "AF614": { - "revision": 1, + "revision": 2, "explanation": "The converter range is only +/-1 V, so a 1.5 V peak sine clips at the limits even though the 12-bit resolution is fine.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_anwendung_dac_adc.html#AF614", "confidence": 8 }, "AF615": { - "revision": 1, + "revision": 2, "explanation": "Sampling rate is a rate: number of samples taken per unit time, usually samples per second.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_sampling.html#AF615", "confidence": 8 }, "AF616": { - "revision": 1, + "revision": 2, "explanation": "The sampling theorem gives the theoretical minimum sampling rate needed to reconstruct a band-limited signal without aliasing.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_abtasttheorem.html#AF616", "confidence": 8 }, "AF617": { - "revision": 1, + "revision": 2, "explanation": "Frequency components above half the sampling frequency fold back into the sampled spectrum; that foldback is aliasing.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_abtasttheorem.html#AF617", "confidence": 8 }, "AF618": { - "revision": 1, - "explanation": "Nyquist requires a sampling rate greater than twice the highest signal frequency, so the smallest safe rate is just above $2 f_{max}$.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "revision": 2, + "explanation": "Nyquist requires a sampling rate greater than twice the highest signal frequency, so the smallest safe rate is just above $2 f_{max}$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_abtasttheorem.html#AF618", "confidence": 8 }, "AF619": { - "revision": 1, + "revision": 2, "explanation": "A 4 kHz speech bandwidth needs just over 8 ksample/s by Nyquist; 9600 samples/s is the smallest listed rate above that limit.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_abtasttheorem.html#AF619", "confidence": 8 }, "AF620": { - "revision": 1, + "revision": 2, "explanation": "A direct-sampling receiver first band-limits the analog input, then the sampling clock controls when the A/D converter takes samples.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_analog_digital_umsetzer.html#AF620", "confidence": 8 }, "AF621": { - "revision": 1, + "revision": 2, "explanation": "Clock jitter moves the sampling instant; with a changing input voltage that timing error becomes amplitude error and appears as added noise.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_analog_digital_umsetzer.html#AF621", "confidence": 8 }, "AF622": { - "revision": 1, + "revision": 2, "explanation": "An anti-alias filter must remove too-high analog frequencies before the A/D converter samples them, so it is a low-pass ahead of the converter.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_anti_alias_filter.html#AF622", "confidence": 8 }, "AF623": { - "revision": 1, - "explanation": "For an 8 ksample/s speech ADC, the useful passband must end below the 4 kHz Nyquist limit and then attenuate sharply.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "revision": 2, + "explanation": "For an 8 ksample/s speech ADC, the useful passband must end below the 4 kHz Nyquist limit and then attenuate sharply. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_anti_alias_filter.html#AF623", "confidence": 8 }, "AF624": { - "revision": 1, + "revision": 2, "explanation": "After D/A conversion, a reconstruction low-pass removes sampling images and smooths the stepped output waveform.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_rekonstruktionsfilter.html#AF624", "confidence": 8 }, "AF625": { - "revision": 1, - "explanation": "The reconstruction filter should pass the wanted speech band but reject images above the 4 kHz Nyquist frequency for an 8 ksample/s stream.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "revision": 2, + "explanation": "The reconstruction filter should pass the wanted speech band but reject images above the 4 kHz Nyquist frequency for an 8 ksample/s stream. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_rekonstruktionsfilter.html#AF625", "confidence": 8 }, "AF626": { - "revision": 1, + "revision": 2, "explanation": "Digital voice transmission encodes speech into bits before modulation; the RF chain then converts the digital waveform to the transmitted signal.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_sende_empfangsketten.html#AF626", "confidence": 8 }, "AF627": { - "revision": 1, + "revision": 2, "explanation": "DATV transmission must encode/compress the video program into a digital transport stream before RF modulation.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_sende_empfangsketten.html#AF627", "confidence": 8 }, "AF628": { - "revision": 1, + "revision": 2, "explanation": "A digital voice receiver reverses the transmit chain: demodulate bits, decode the voice data, then convert it back to audio.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_sende_empfangsketten.html#AF628", "confidence": 8 }, "AF629": { - "revision": 1, + "revision": 2, "explanation": "A DATV receiver first recovers the digital transport stream from RF and then decodes the video and audio content.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_sende_empfangsketten.html#AF629", "confidence": 8 }, "AF630": { - "revision": 1, + "revision": 2, "explanation": "The FFT is an efficient discrete Fourier transform, used to convert sampled time-domain data into frequency-domain bins.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_fourier_transformation.html#AF630", "confidence": 8 }, "AF631": { - "revision": 1, + "revision": 2, "explanation": "Digital filters are implemented as algorithms or logic, and the two standard response classes are FIR and IIR.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_digitale_filter.html#AF631", "confidence": 8 }, "AF632": { - "revision": 1, - "explanation": "Quadrature modulation needs two carriers in quadrature; quadrature means a 90 degree phase difference.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "revision": 2, + "explanation": "Quadrature modulation needs two carriers in quadrature; quadrature means a 90 degree phase difference. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_iq_verfahren.html#AF632", "confidence": 8 }, "AF633": { - "revision": 1, + "revision": 2, "explanation": "I is the in-phase component relative to the reference oscillator, while Q is the component shifted by 90 degrees.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_iq_verfahren.html#AF633", "confidence": 8 }, "AF634": { - "revision": 1, - "explanation": "Complex I/Q sampling represents positive and negative baseband frequencies around the carrier, so 48 ksample/s covers -24 kHz to +24 kHz.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "revision": 3, + "explanation": "Complex I/Q sampling represents positive and negative baseband frequencies around the carrier, so 48 ksample/s covers -24 kHz to +24 kHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_iq_verfahren.html#AF634", "confidence": 8 }, "AF635": { - "revision": 1, - "explanation": "For complex I/Q data, the displayed baseband span equals the sample rate, split symmetrically around zero: 96 ksample/s gives +/-48 kHz.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "revision": 3, + "explanation": "For complex I/Q data, the displayed baseband span equals the sample rate, split symmetrically around zero: 96 ksample/s gives +/-48 kHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_iq_verfahren.html#AF635", "confidence": 8 }, "AF636": { - "revision": 1, - "explanation": "With I and Q each sampled at 10 Msample/s, the complex baseband span is 10 MHz total, i.e. -5 MHz to +5 MHz.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "revision": 3, + "explanation": "With I and Q each sampled at 10 Msample/s, the complex baseband span is 10 MHz total, i.e. -5 MHz to +5 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_iq_verfahren.html#AF636", "confidence": 8 }, "AF637": { - "revision": 1, + "revision": 2, "explanation": "Latency is elapsed delay through a link or processing chain, so it is a time quantity measured in seconds or fractions of a second.", - "source": "https://50ohm.de/future/NEA_slide_nea_digitale_signalverarbeitung.html", + "source": "https://50ohm.de/NEA_latenz.html#AF637", "confidence": 8 }, "AF701": { - "revision": 1, + "revision": 2, "explanation": "Block 1 is on the operator side, so it is the local computer or control head used to create audio and control data.", - "source": "https://50ohm.de/EA_remote_station.html", + "source": "https://50ohm.de/NEA_remote_station.html#AF701", "confidence": 8 }, "AF702": { - "revision": 1, + "revision": 2, "explanation": "Block 2 is at the remote site and bridges the network to radio control/audio, which is the job of a computer or remote interface.", - "source": "https://50ohm.de/EA_remote_station.html", + "source": "https://50ohm.de/NEA_remote_station.html#AF702", "confidence": 8 }, "AF703": { - "revision": 1, + "revision": 2, "explanation": "The operator-side block packetizes local audio and control commands before sending them through the network.", - "source": "https://50ohm.de/EA_remote_station.html", + "source": "https://50ohm.de/NEA_remote_station.html#AF703", "confidence": 8 }, "AF704": { - "revision": 1, + "revision": 2, "explanation": "At the remote site, block 2 converts incoming network packets back into audio and control signals for the radio equipment.", - "source": "https://50ohm.de/EA_remote_station.html", + "source": "https://50ohm.de/NEA_remote_station.html#AF704", "confidence": 8 }, "AF705": { - "revision": 1, + "revision": 2, "explanation": "The RF carrier is generated by the actual transceiver in block 3, not by the network or control interface.", - "source": "https://50ohm.de/EA_remote_station.html", + "source": "https://50ohm.de/NEA_remote_station.html#AF705", "confidence": 8 }, "AF706": { - "revision": 1, + "revision": 2, "explanation": "Self-interference occurs at the remote site, so it can disturb the transceiver and remote-control electronics located there.", - "source": "https://50ohm.de/EA_remote_station.html", + "source": "https://50ohm.de/NEA_remote_station.html#AF706", "confidence": 8 }, "AF707": { - "revision": 1, + "revision": 2, "explanation": "If the transceiver stops accepting control commands, removing its supply power remotely is the direct way to stop transmission.", - "source": "https://50ohm.de/EA_remote_station.html", + "source": "https://50ohm.de/NEA_remote_station.html#AF707", "confidence": 8 }, "AF708": { - "revision": 1, + "revision": 2, "explanation": "A watchdog detects missing keep-alive communication and forces a safe state, preventing stuck transmission after link failure.", - "source": "https://50ohm.de/EA_remote_station.html", + "source": "https://50ohm.de/NEA_remote_station.html#AF708", "confidence": 8 }, "AF709": { - "revision": 1, + "revision": 2, "explanation": "Remote operation adds network, buffering, codec and control delays, so received and transmitted signals arrive later.", - "source": "https://50ohm.de/EA_remote_station.html", + "source": "https://50ohm.de/NEA_remote_station.html#AF709", "confidence": 8 }, "AF710": { - "revision": 1, + "revision": 2, "explanation": "In remote operation, latency is the time delay between user action or audio and the corresponding event at the remote station.", - "source": "https://50ohm.de/EA_remote_station.html", + "source": "https://50ohm.de/NEA_remote_station.html#AF710", "confidence": 8 }, "AG101": { - "revision": 1, - "explanation": "A half-wave dipole has total length $0.95 c/(2f)$; at 14.2 MHz that is about 10.04 m total, or 5.02 m per side.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A half-wave dipole has total length $0.95 c/(2f)$; at 14.2 MHz that is about 10.04 m total, or 5.02 m per side. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_2.html#AG101", "confidence": 8 }, "AG102": { - "revision": 1, - "explanation": "Using $0.95 c/(2f)$ at 7.1 MHz gives about 20.08 m total dipole length, so each half is about 10.04 m.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "Using $0.95 c/(2f)$ at 7.1 MHz gives about 20.08 m total dipole length, so each half is about 10.04 m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_2.html#AG102", "confidence": 8 }, "AG103": { - "revision": 1, - "explanation": "For a shortened half-wave dipole, $f = 0.95 c/(2l)$; with 20 m total length this is about 7.125 MHz.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 3, + "explanation": "For a shortened half-wave dipole, $f = 0.95 c/(2l)$; with 20 m total length this is about 7.125 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_2.html#AG103", "confidence": 8 }, "AG104": { - "revision": 1, - "explanation": "A quarter-wave groundplane uses quarter-wave radiator and radials; $0.95 c/(4 \\cdot 7.1 MHz)$ is about 10.04 m.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A quarter-wave groundplane uses quarter-wave radiator and radials; $0.95 c/(4 \\cdot 7.1 MHz)$ is about 10.04 m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_2.html#AG104", "confidence": 8 }, "AG105": { - "revision": 1, - "explanation": "A 5/8-wave vertical length is $0.97 \\cdot 5/8 \\cdot c/f$; at 14.2 MHz this is about 12.8 m.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A 5/8-wave vertical length is $0.97 \\cdot 5/8 \\cdot c/f$; at 14.2 MHz this is about 12.8 m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_2.html#AG105", "confidence": 8 }, "AG106": { - "revision": 1, + "revision": 2, "explanation": "A loading coil adds inductive reactance, making a physically short radiator behave electrically longer.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_elektrische_verlaengerung_verkuerzung.html#AG106", "confidence": 8 }, "AG107": { - "revision": 1, + "revision": 2, "explanation": "Series or top capacitance can offset excess inductive electrical length, so the radiator behaves electrically shorter.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_elektrische_verlaengerung_verkuerzung.html#AG107", "confidence": 8 }, "AG108": { - "revision": 1, + "revision": 2, "explanation": "A twice-15 m dipole is physically short for 3.6 MHz; loading coils in both arms add inductance and bring it to resonance.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_elektrische_verlaengerung_verkuerzung.html#AG108", "confidence": 8 }, "AG109": { - "revision": 1, + "revision": 2, "explanation": "The inserted parallel resonant traps isolate or load parts of the dipole by band, which is the defining feature of a trap dipole.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_traps.html#AG109", "confidence": 8 }, "AG110": { - "revision": 1, + "revision": 2, "explanation": "A trap presents high impedance near its resonance and different reactance away from it, allowing one dipole to work on multiple bands.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_traps.html#AG110", "confidence": 8 }, "AG111": { - "revision": 1, + "revision": 2, "explanation": "Below the trap resonance the LC trap behaves mainly inductively, adding electrical length for the lower-frequency band.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_traps.html#AG111", "confidence": 8 }, "AG112": { - "revision": 1, + "revision": 2, "explanation": "At its resonant frequency a parallel LC trap has high impedance, so it blocks the rest of the wire and acts as a band stop.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_traps.html#AG112", "confidence": 8 }, "AG113": { - "revision": 1, + "revision": 2, "explanation": "Above the trap resonance the trap's equivalent reactance is capacitive, reducing the effective electrical length for the higher band.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_traps.html#AG113", "confidence": 8 }, "AG114": { - "revision": 1, - "explanation": "In a 20/15/10 m trap dipole, the inner trap pair must stop the 15 m current, so it is tuned near 21.2 MHz.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 3, + "explanation": "In a 20/15/10 m trap dipole, the inner trap pair must stop the 15 m current, so it is tuned near 21.2 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_traps.html#AG114", "confidence": 8 }, "AG115": { - "revision": 1, - "explanation": "The outer trap pair separates the 10 m section, so it is tuned near the 10 m operating frequency around 29 MHz.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 3, + "explanation": "The outer trap pair separates the 10 m section, so it is tuned near the 10 m operating frequency around 29 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_traps.html#AG115", "confidence": 8 }, "AG116": { - "revision": 1, - "explanation": "For 80 m a half-wave section is roughly 40 m, and traps for a 160/80 m antenna are tuned near the 80 m band around 3.65 MHz.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "For 80 m a half-wave section is roughly 40 m, and traps for a 160/80 m antenna are tuned near the 80 m band around 3.65 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_traps.html#AG116", "confidence": 8 }, "AG117": { - "revision": 1, + "revision": 2, "explanation": "A triangular full-wave wire loop is conventionally called a delta loop.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_antennenformen_3.html#AG117", "confidence": 8 }, "AG118": { - "revision": 1, + "revision": 2, "explanation": "A full-wave loop length is approximately $1.02 c/f$; at 7.1 MHz this gives about 43.1 m of wire.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_2.html#AG118", "confidence": 8 }, "AG119": { - "revision": 1, + "revision": 2, "explanation": "A quad loop is a full-wave loop divided into four equal sides, so each side is one quarter wavelength electrically.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_antennenformen_3.html#AG119", "confidence": 8 }, "AG120": { - "revision": 1, + "revision": 2, "explanation": "A Zeppelin antenna is the classic end-fed wire fed through a parallel-wire feeder at one end.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_antennenformen_3.html#AG120", "confidence": 8 }, "AG121": { - "revision": 1, + "revision": 2, "explanation": "The G5RV is recognized by its specified dipole length and matching section of open-wire feedline before the coax transition.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_antennenformen_3.html#AG121", "confidence": 8 }, "AG122": { - "revision": 1, + "revision": 2, "explanation": "A Windom antenna is an off-center-fed wire dipole, so the unequal wire lengths identify it.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_antennenformen_3.html#AG122", "confidence": 8 }, "AG123": { - "revision": 1, + "revision": 2, "explanation": "An end-fed multiband wire uses an end feed and matching/choking at the feed point; the sketch labels that end-fed multiband layout.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_antennenformen_3.html#AG123", "confidence": 8 }, "AG124": { - "revision": 1, + "revision": 2, "explanation": "An end-fed half-wave style multiband antenna is resonant on its intended bands and uses the matching unit plus choke at the end feed.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_antennenformen_3.html#AG124", "confidence": 8 }, "AG125": { - "revision": 1, + "revision": 2, "explanation": "NVIS needs high-angle radiation, which low horizontal wires produce when kept around a quarter wavelength or less above ground.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_nvis.html#AG125", "confidence": 8 }, "AG126": { - "revision": 1, - "explanation": "Circular polarization requires two perpendicular linear fields with equal amplitude and 90 degree phase difference, so one Yagi must be delayed by a quarter wavelength.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "Circular polarization requires two perpendicular linear fields with equal amplitude and 90 degree phase difference, so one Yagi must be delayed by a quarter wavelength. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_yagi_uda_3.html#AG126", "confidence": 8 }, "AG127": { - "revision": 1, + "revision": 2, "explanation": "An offset dish moves the feed out of the aperture, avoiding feed blockage and improving illumination compared with a centered feed.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_offsetspiegel.html#AG127", "confidence": 8 }, "AG201": { - "revision": 1, + "revision": 2, "explanation": "On HF, both horizontal and vertical antennas are common; the ionosphere may change polarization anyway, so neither is exclusive.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_polarisation_3.html#AG201", "confidence": 8 }, "AG202": { - "revision": 1, + "revision": 2, "explanation": "Real conductors have diameter and environmental capacitance, which increase electrical length, so the physical wire must be shortened from the ideal free-space value.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_2.html#AG202", "confidence": 8 }, "AG203": { - "revision": 1, + "revision": 2, "explanation": "The 28 MHz case is the highest listed harmonic, so it shows the largest number of current half-waves on the same dipole.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_frequenzabhaengige_stromverteilung.html#AG203", "confidence": 8 }, "AG204": { - "revision": 1, + "revision": 2, "explanation": "At 14 MHz the 20 m dipole is excited at the next lower shown harmonic pattern, with fewer current lobes than at 28 MHz.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_frequenzabhaengige_stromverteilung.html#AG204", "confidence": 8 }, "AG205": { - "revision": 1, + "revision": 2, "explanation": "At 7 MHz the same 20 m wire is near one full wavelength overall, matching the intermediate current distribution.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_frequenzabhaengige_stromverteilung.html#AG205", "confidence": 8 }, "AG206": { - "revision": 1, + "revision": 2, "explanation": "At 3.5 MHz the 20 m dipole is near its half-wave fundamental, so it has the simplest current distribution with the central maximum.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_frequenzabhaengige_stromverteilung.html#AG206", "confidence": 8 }, "AG207": { - "revision": 1, - "explanation": "A center-fed half-wave dipole and its odd harmonics have current maximum at the feed point, giving series resonance and low feed impedance.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A center-fed half-wave dipole and its odd harmonics have current maximum at the feed point, giving series resonance and low feed impedance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_strom_spannung_speisung_2.html#AG207", "confidence": 8 }, "AG208": { - "revision": 1, - "explanation": "At even harmonics the center feed lies at a voltage maximum/current minimum, so the dipole is voltage-fed and high impedance.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "At even harmonics the center feed lies at a voltage maximum/current minimum, so the dipole is voltage-fed and high impedance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_strom_spannung_speisung_2.html#AG208", "confidence": 8 }, "AG209": { - "revision": 1, - "explanation": "At resonance the reactive parts cancel, leaving the feedpoint impedance mainly resistive.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "At resonance the reactive parts cancel, leaving the feedpoint impedance mainly resistive. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_fusspunktimpedanz_2.html#AG209", "confidence": 8 }, "AG210": { - "revision": 1, - "explanation": "Below resonance a dipole is electrically too short and capacitive; above resonance it is electrically too long and inductive.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "Below resonance a dipole is electrically too short and capacitive; above resonance it is electrically too long and inductive. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_fusspunktimpedanz_2.html#AG210", "confidence": 8 }, "AG211": { - "revision": 1, - "explanation": "A half-wave dipole high enough above ground has a feed resistance close to the textbook free-space value, roughly 65 to 75 ohms.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A half-wave dipole high enough above ground has a feed resistance close to the textbook free-space value, roughly 65 to 75 ohms. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_fusspunktimpedanz_2.html#AG211", "confidence": 8 }, "AG212": { - "revision": 1, + "revision": 2, "explanation": "Yagi feed impedance depends strongly on mutual coupling, which is set by spacing between driven element, reflector and directors.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_yagi_uda_3.html#AG212", "confidence": 8 }, "AG213": { - "revision": 1, - "explanation": "Antenna gain over a dipole compares the power needed by the reference dipole with the power needed by the directional antenna for the same field strength.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "Antenna gain over a dipole compares the power needed by the reference dipole with the power needed by the directional antenna for the same field strength. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_vor_rueck_verhaeltnis.html#AG213", "confidence": 8 }, "AG214": { - "revision": 1, - "explanation": "Front-to-back ratio compares radiation in the main direction with radiation in the opposite rear direction.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "Front-to-back ratio compares radiation in the main direction with radiation in the opposite rear direction. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_vor_rueck_verhaeltnis.html#AG214", "confidence": 8 }, "AG215": { - "revision": 1, - "explanation": "The rear ERP is transmit power times forward gain divided by front-to-back ratio: 100 W x 10 / 100 = 10 W.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 3, + "explanation": "The rear ERP is transmit power times forward gain divided by front-to-back ratio: 100 W x 10 / 100 = 10 W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_vor_rueck_verhaeltnis.html#AG215", "confidence": 8 }, "AG216": { - "revision": 1, - "explanation": "15 dBd is a factor 31.6 and 25 dB front-to-back is a factor 316; $6 W \\cdot 31.6 / 316$ is about 0.6 W rear ERP.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 3, + "explanation": "15 dBd is a factor 31.6 and 25 dB front-to-back is a factor 316; $6 W \\cdot 31.6 / 316$ is about 0.6 W rear ERP. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_vor_rueck_verhaeltnis.html#AG216", "confidence": 8 }, "AG217": { - "revision": 1, - "explanation": "Front-to-back ratio is a power ratio: $10 log10(15/0.6)$ is about 14 dB.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 3, + "explanation": "Front-to-back ratio is a power ratio: $10 log10(15/0.6)$ is about 14 dB. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_vor_rueck_verhaeltnis.html#AG217", "confidence": 8 }, "AG218": { - "revision": 1, - "explanation": "For field strengths, use 20 log10 of the voltage ratio: 300/128 gives 7.4 dBd, and 300/20 gives 23.5 dB front-to-back.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 3, + "explanation": "For field strengths, use 20 log10 of the voltage ratio: 300/128 gives 7.4 dBd, and 300/20 gives 23.5 dB front-to-back. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_vor_rueck_verhaeltnis.html#AG218", "confidence": 8 }, "AG219": { - "revision": 1, - "explanation": "Half-power is 3 dB down; field strength is proportional to the square root of power, so the boundary is $1/sqrt(2) = 0.707$ of maximum field.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "Half-power is 3 dB down; field strength is proportional to the square root of power, so the boundary is $1/sqrt(2) = 0.707$ of maximum field. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_halbwertsbreite.html#AG219", "confidence": 8 }, "AG220": { - "revision": 1, - "explanation": "The half-power beamwidth is read at the 0.707 relative-field circle, which is the point marked c in the diagram.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "The half-power beamwidth is read at the 0.707 relative-field circle, which is the point marked c in the diagram. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_halbwertsbreite.html#AG220", "confidence": 8 }, "AG221": { - "revision": 1, + "revision": 2, "explanation": "Beamwidth is the angular separation between the two intersections of the main lobe with the 0.707 field-strength circle; the sketch gives about 55 degrees.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_halbwertsbreite.html#AG221", "confidence": 8 }, "AG222": { - "revision": 1, + "revision": 2, "explanation": "Adding Yagi elements increases directivity, which narrows the main lobe and therefore reduces the opening angle.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_yagi_uda_3.html#AG222", "confidence": 8 }, "AG223": { - "revision": 1, - "explanation": "A 5/8-wave vertical over ground has a low elevation-angle maximum, useful for flat long-distance HF radiation.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A 5/8-wave vertical over ground has a low elevation-angle maximum, useful for flat long-distance HF radiation. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_antennenformen_3.html#AG223", "confidence": 8 }, "AG224": { - "revision": 1, + "revision": 2, "explanation": "A low horizontal NVIS antenna sends most energy upward, so the returned sky wave fills the normal skip zone near the transmitter.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_nvis.html#AG224", "confidence": 8 }, "AG225": { - "revision": 1, + "revision": 2, "explanation": "Dish feeds need to illuminate the reflector efficiently at microwave frequencies; dipoles, helices and horn antennas are standard feed types.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_parbolspiegel_2.html#AG225", "confidence": 8 }, "AG226": { - "revision": 1, - "explanation": "Parabolic gain rises with aperture diameter over wavelength: with 30 cm at 5.7 GHz and ideal efficiency, $G=(pi D/lambda)^2$ gives about 25 dBi.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "Parabolic gain rises with aperture diameter over wavelength: with 30 cm at 5.7 GHz and ideal efficiency, $G=(pi D/lambda)^2$ gives about 25 dBi. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_parbolspiegel_2.html#AG226", "confidence": 8 }, "AG227": { - "revision": 1, - "explanation": "At the same frequency, increasing dish diameter to 80 cm increases aperture area strongly; the ideal-gain formula gives about 33.6 dBi.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "At the same frequency, increasing dish diameter to 80 cm increases aperture area strongly; the ideal-gain formula gives about 33.6 dBi. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_parbolspiegel_2.html#AG227", "confidence": 8 }, "AG228": { - "revision": 1, - "explanation": "For a fixed 80 cm dish, the shorter 10.4 GHz wavelength increases aperture gain to about 38.8 dBi.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "For a fixed 80 cm dish, the shorter 10.4 GHz wavelength increases aperture gain to about 38.8 dBi. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_parbolspiegel_2.html#AG228", "confidence": 8 }, "AG229": { - "revision": 1, - "explanation": "A 1.2 m dish at 10.4 GHz has a large diameter-to-wavelength ratio, so the ideal parabolic-gain formula gives about 42.3 dBi.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A 1.2 m dish at 10.4 GHz has a large diameter-to-wavelength ratio, so the ideal parabolic-gain formula gives about 42.3 dBi. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_parbolspiegel_2.html#AG229", "confidence": 8 }, "AG301": { - "revision": 1, - "explanation": "A shielded feed line keeps high RF fields inside the cable and reduces coupling into building wiring and equipment.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A shielded feed line keeps high RF fields inside the cable and reduces coupling into building wiring and equipment. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_3.html#AG301", "confidence": 8 }, "AG302": { - "revision": 1, + "revision": 2, "explanation": "Common coax dielectrics are low-loss RF plastics: PTFE, solid polyethylene and foamed polyethylene.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_3.html#AG302", "confidence": 8 }, "AG303": { - "revision": 1, + "revision": 2, "explanation": "The important RF cable properties are characteristic impedance, attenuation and velocity factor, because they determine matching, loss and electrical length.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_3.html#AG303", "confidence": 8 }, "AG304": { - "revision": 1, + "revision": 2, "explanation": "A line is matched when the load equals its characteristic impedance; then no reflected wave is produced.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_wellenwiderstand.html#AG304", "confidence": 8 }, "AG305": { - "revision": 1, - "explanation": "For open wire line, $Z_0$ rises with conductor spacing and falls with conductor diameter; the given 20 cm spacing and 2 mm wire give about 635 ohms.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "For open wire line, $Z_0$ rises with conductor spacing and falls with conductor diameter; the given 20 cm spacing and 2 mm wire give about 635 ohms. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wellenwiderstand.html#AG305", "confidence": 8 }, "AG306": { - "revision": 1, - "explanation": "For air coax, $Z_0 = 60 ln(D/d)$; with 5 mm over 1 mm this is about 97 ohms.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "For air coax, $Z_0 = 60 ln(D/d)$; with 5 mm over 1 mm this is about 97 ohms. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wellenwiderstand.html#AG306", "confidence": 8 }, "AG307": { - "revision": 1, + "revision": 2, "explanation": "Polyethylene lowers coax impedance by the dielectric factor; the given dimensions correspond to a common 75 ohm cable geometry.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_wellenwiderstand.html#AG307", "confidence": 8 }, "AG308": { - "revision": 1, + "revision": 2, "explanation": "Over 60 m at 29 MHz, the cable must stay below 2 dB total loss; the 10.3 mm PE-foam cable is the thinnest listed type meeting that limit.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_kabeldaempfung_2.html#AG308", "confidence": 8 }, "AG309": { - "revision": 1, + "revision": 2, "explanation": "At 2.35 GHz coax loss is high, so a 20 m run needs the low-loss 12.7 mm PE-foam cable to stay within 4 dB.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_kabeldaempfung_2.html#AG309", "confidence": 8 }, "AG310": { - "revision": 1, + "revision": 2, "explanation": "At 5.7 GHz even short coax is lossy; among the listed cables, only the 12.7 mm PE-foam type keeps 8 m below 3 dB.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_kabeldaempfung_2.html#AG310", "confidence": 8 }, "AG311": { - "revision": 1, + "revision": 2, "explanation": "Wide-spaced open-wire line has little dielectric loss and lower RF resistance for the same conductor size, so it has the lowest HF loss.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_kabeldaempfung_2.html#AG311", "confidence": 8 }, "AG312": { - "revision": 1, + "revision": 2, "explanation": "A balanced two-wire line carries equal and opposite currents and voltages; without common-mode current the external fields mostly cancel.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_3.html#AG312", "confidence": 8 }, "AG313": { - "revision": 1, + "revision": 2, "explanation": "Air has nearly the same wave speed as free space, so an air-insulated parallel line has velocity factor close to 1.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_2.html#AG313", "confidence": 8 }, "AG314": { - "revision": 1, + "revision": 2, "explanation": "The dielectric in coax slows wave propagation compared with free space, so its physical wavelength is shorter.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_3.html#AG314", "confidence": 8 }, "AG315": { - "revision": 1, + "revision": 2, "explanation": "Solid polyethylene has a relative permittivity that gives a typical coax velocity factor near 0.66.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_2.html#AG315", "confidence": 8 }, "AG316": { - "revision": 1, + "revision": 2, "explanation": "Free-space wavelength at 145 MHz is about 2.07 m; multiplying by velocity factor 0.66 gives about 1.37 m.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_2.html#AG316", "confidence": 8 }, "AG317": { - "revision": 1, - "explanation": "A quarter wave at 145 MHz is about 0.517 m in free space; with velocity factor 0.66 it is about 0.342 m.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A quarter wave at 145 MHz is about 0.517 m in free space; with velocity factor 0.66 it is about 0.342 m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_3.html#AG317", "confidence": 8 }, "AG318": { - "revision": 1, + "revision": 2, "explanation": "At high frequency, current crowds toward the conductor surface; this is the skin effect.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_skineffekt.html#AG318", "confidence": 8 }, "AG319": { - "revision": 1, + "revision": 2, "explanation": "Skin effect reduces the effective conducting cross-section, so RF resistance and cable loss increase with frequency.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_skineffekt.html#AG319", "confidence": 8 }, "AG320": { - "revision": 1, + "revision": 2, "explanation": "A Lecher line resonates when its physical/electrical length fits a standing-wave condition, so length is the key parameter.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_lecherleitung.html#AG320", "confidence": 8 }, "AG401": { - "revision": 1, + "revision": 2, "explanation": "Maximum power transfer occurs when load impedance equals the source impedance; a 50 ohm source therefore wants a 50 ohm load.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_innenwiderstand.html#AG401", "confidence": 8 }, "AG402": { - "revision": 1, - "explanation": "A 3 dB line loss halves the power on the way to the far end; with open or short circuit, that 50 W reaching the end is reflected.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 3, + "explanation": "A 3 dB line loss halves the power on the way to the far end; with open or short circuit, that 50 W reaching the end is reflected. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_swr_3.html#AG402", "confidence": 8 }, "AG403": { - "revision": 1, + "revision": 2, "explanation": "The line looks matched with a dummy load but not with the antenna, so the fault is at the antenna or its termination, not in the line.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_swr_3.html#AG403", "confidence": 8 }, "AG404": { - "revision": 1, + "revision": 2, "explanation": "With the end open, reflection travels down and back through 5 dB each way; the 10 dB round-trip loss makes the input SWR look only about 1.9.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_swr_3.html#AG404", "confidence": 8 }, "AG405": { - "revision": 1, + "revision": 2, "explanation": "A folded dipole is roughly 240 to 300 ohms, so feeding it with 75 ohm coax gives an impedance ratio around 3.2 to 4.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_swr_3.html#AG405", "confidence": 8 }, "AG406": { - "revision": 1, + "revision": 2, "explanation": "A pi network can transform impedance while its capacitors and inductor also form a low-pass path that suppresses harmonics.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_impedanztransformation.html#AG406", "confidence": 8 }, "AG407": { - "revision": 1, - "explanation": "A quarter wavelength is one quarter of a full 360 degree RF cycle, so the phase shift is 90 degrees.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A quarter wavelength is one quarter of a full 360 degree RF cycle, so the phase shift is 90 degrees. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leitung_phasenverschiebung.html#AG407", "confidence": 8 }, "AG408": { - "revision": 1, - "explanation": "One full wavelength produces a 360 degree phase shift, which is equivalent to 0 degrees at the input reference.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "One full wavelength produces a 360 degree phase shift, which is equivalent to 0 degrees at the input reference. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leitung_phasenverschiebung.html#AG408", "confidence": 8 }, "AG409": { - "revision": 1, - "explanation": "A quarter-wave line inverts impedance: a short circuit at one end appears as very high impedance at the other.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A quarter-wave line inverts impedance: a short circuit at one end appears as very high impedance at the other. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_lecherleitung.html#AG409", "confidence": 8 }, "AG410": { - "revision": 1, - "explanation": "The quarter-wave section transforms the far-end condition so point X is at a current maximum and nearly zero impedance.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "The quarter-wave section transforms the far-end condition so point X is at a current maximum and nearly zero impedance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_lecherleitung.html#AG410", "confidence": 8 }, "AG411": { - "revision": 1, + "revision": 2, "explanation": "A lossless quarter-wave line transforms an open circuit into a short-circuit-like low impedance at the other end.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_lecherleitung.html#AG411", "confidence": 8 }, "AG412": { - "revision": 1, + "revision": 2, "explanation": "A half-wave line repeats its load impedance at the input, so 50 ohms remains 50 ohms.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_impedanztransformation.html#AG412", "confidence": 8 }, "AG413": { - "revision": 1, - "explanation": "A half-wave dipole is low impedance at its feed, and a half-wave feed line repeats that low impedance at its input.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A half-wave dipole is low impedance at its feed, and a half-wave feed line repeats that low impedance at its input. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_impedanztransformation.html#AG413", "confidence": 8 }, "AG414": { - "revision": 1, - "explanation": "A full-wave dipole is voltage-fed and high impedance at the feed point, and a half-wave line repeats that high impedance.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A full-wave dipole is voltage-fed and high impedance at the feed point, and a half-wave line repeats that high impedance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_impedanztransformation.html#AG414", "confidence": 8 }, "AG415": { - "revision": 1, - "explanation": "A quarter-wave line transforms impedance, so a high-impedance full-wave dipole becomes low impedance at the line input.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A quarter-wave line transforms impedance, so a high-impedance full-wave dipole becomes low impedance at the line input. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_impedanztransformation.html#AG415", "confidence": 8 }, "AG416": { - "revision": 1, - "explanation": "A half-wave transmission line repeats the load impedance independent of its own characteristic impedance, so the input remains 70 ohms.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A half-wave transmission line repeats the load impedance independent of its own characteristic impedance, so the input remains 70 ohms. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_impedanztransformation.html#AG416", "confidence": 8 }, "AG417": { - "revision": 1, - "explanation": "For a quarter-wave transformer, $Z_t = sqrt(Z_1 Z_2)$; $sqrt(60 \\cdot 240)$ is 120 ohms.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "For a quarter-wave transformer, $Z_t = sqrt(Z_1 Z_2)$; $sqrt(60 \\cdot 240)$ is 120 ohms. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_impedanztransformation.html#AG417", "confidence": 8 }, "AG418": { - "revision": 1, - "explanation": "The quarter-wave transformer impedance is $sqrt(240 \\cdot 600)$, which is about 380 ohms.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "The quarter-wave transformer impedance is $sqrt(240 \\cdot 600)$, which is about 380 ohms. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_impedanztransformation.html#AG418", "confidence": 8 }, "AG419": { - "revision": 1, - "explanation": "An end-fed resonant wire has a high feed impedance when its length is a half wavelength or an integer multiple of that.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "An end-fed resonant wire has a high feed impedance when its length is a half wavelength or an integer multiple of that. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_antennenformen_3.html#AG419", "confidence": 8 }, "AG420": { - "revision": 1, - "explanation": "A coax feed is unbalanced while a dipole is balanced, so a balun or equivalent phasing line provides the symmetry transition.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A coax feed is unbalanced while a dipole is balanced, so a balun or equivalent phasing line provides the symmetry transition. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_umwegleitung.html#AG420", "confidence": 8 }, "AG421": { - "revision": 1, + "revision": 2, "explanation": "A 2:1 turns ratio gives a 4:1 impedance ratio; transforming 50 ohms by 4 gives 200 ohms.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_mantelwellen_2.html#AG421", "confidence": 8 }, "AG422": { - "revision": 1, + "revision": 2, "explanation": "The balun uses the winding ratio to transform the 200 ohm balanced load down by 4:1, so the coax-side impedance is 50 ohms.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_mantelwellen_2.html#AG422", "confidence": 8 }, "AG423": { - "revision": 1, - "explanation": "The half-wave bypass line provides both impedance transformation and phase reversal, matching the folded dipole's high balanced impedance to lower unbalanced coax.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "The half-wave bypass line provides both impedance transformation and phase reversal, matching the folded dipole's high balanced impedance to lower unbalanced coax. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_umwegleitung.html#AG423", "confidence": 8 }, "AG424": { - "revision": 1, - "explanation": "Each folded-dipole terminal is about 120 ohms to ground; the half-wave detour preserves magnitude but reverses phase, so the two 120 ohm paths combine to 60 ohms.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "Each folded-dipole terminal is about 120 ohms to ground; the half-wave detour preserves magnitude but reverses phase, so the two 120 ohm paths combine to 60 ohms. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_umwegleitung.html#AG424", "confidence": 8 }, "AG425": { - "revision": 1, + "revision": 2, "explanation": "Common-mode current on the outside of the coax shield is the mantle-wave condition; differential current inside the coax is normal feed current.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_mantelwellen_2.html#AG425", "confidence": 8 }, "AG426": { - "revision": 1, + "revision": 2, "explanation": "A current-compensated choke cancels differential fields but presents high impedance to common-mode current on the outside of the feed line.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_mantelwellen_2.html#AG426", "confidence": 8 }, "AG427": { - "revision": 1, - "explanation": "Common-mode current arises when the antenna/feed system is unbalanced or nearby objects couple RF onto the outside of the coax shield.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "Common-mode current arises when the antenna/feed system is unbalanced or nearby objects couple RF onto the outside of the coax shield. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_mantelwellen_2.html#AG427", "confidence": 8 }, "AG428": { - "revision": 1, - "explanation": "A common-mode choke or suitable balun raises the impedance for the unwanted shield current while leaving the wanted differential feed current mostly unaffected.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "A common-mode choke or suitable balun raises the impedance for the unwanted shield current while leaving the wanted differential feed current mostly unaffected. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_mantelwellen_2.html#AG428", "confidence": 8 }, "AG429": { - "revision": 1, + "revision": 2, "explanation": "A voltage balun enforces terminal voltage symmetry but cannot remove every environmental imbalance; asymmetric surroundings can still drive shield current.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_mantelwellen_2.html#AG429", "confidence": 8 }, "AG501": { - "revision": 1, + "revision": 2, "explanation": "ERP is radiated power referenced to a half-wave dipole, so it is antenna input power times gain relative to a dipole in the specified direction.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_effektive_strahlungsleistung_erp_2.html#AG501", "confidence": 8 }, "AG502": { - "revision": 1, - "explanation": "First subtract feed-line loss from transmitter power to get antenna input power; multiplying by antenna gain relative to a dipole gives ERP.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 2, + "explanation": "First subtract feed-line loss from transmitter power to get antenna input power; multiplying by antenna gain relative to a dipole gives ERP. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_effektive_strahlungsleistung_erp_2.html#AG502", "confidence": 8 }, "AG503": { - "revision": 1, - "explanation": "A 20 dB loss is a factor of 100; 50 W divided by 100 gives 0.5 W ERP.", - "source": "https://50ohm.de/future/NEA_slide_nea_antennen_uebertragungsleitungen.html", + "revision": 3, + "explanation": "A 20 dB loss is a factor of 100; 50 W divided by 100 gives 0.5 W ERP. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_effektive_strahlungsleistung_erp_2.html#AG503", "confidence": 8 }, "AH101": { - "revision": 1, + "revision": 2, "explanation": "Solar UV radiation ionizes molecules in the ionosphere; the resulting free electrons refract radio waves back toward Earth.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH101", "confidence": 8 }, "AH102": { - "revision": 1, + "revision": 2, "explanation": "Solar flux is the Sun's radio emission around the GHz range; higher values indicate stronger solar activity and more ionization for upper-HF propagation.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH102", "confidence": 8 }, "AH103": { - "revision": 1, + "revision": 2, "explanation": "The D region is the lowest ionospheric region relevant to HF propagation, typically around 50 to 90 km altitude.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH103", "confidence": 8 }, "AH104": { - "revision": 1, + "revision": 2, "explanation": "The E region sits above the D region and below the F region, roughly 90 to 130 km altitude.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH104", "confidence": 8 }, "AH105": { - "revision": 1, + "revision": 2, "explanation": "In daytime the F1 region forms below F2, typically around 130 to 200 km altitude.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH105", "confidence": 8 }, "AH106": { - "revision": 1, + "revision": 2, "explanation": "The F2 region is the highest regular HF-refraction region and can reach roughly 250 to 450 km on a summer day.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH106", "confidence": 8 }, "AH107": { - "revision": 1, + "revision": 2, "explanation": "For DX, F2 refraction is usually wanted; an intervening F1 region can absorb or bend the wave before it reaches F2 effectively.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH107", "confidence": 8 }, "AH108": { - "revision": 1, + "revision": 2, "explanation": "Solar heating is strongest around summer midday, so the F2 region expands upward then.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH108", "confidence": 8 }, "AH201": { - "revision": 1, + "revision": 2, "explanation": "Hamburg to Munich is a relatively short HF path; around midday, 40 m commonly supports such regional ionospheric links.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH201", "confidence": 8 }, "AH202": { - "revision": 1, - "explanation": "In a sunspot minimum the higher HF bands open less reliably, while 20 m often remains the best daily long-distance band.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "revision": 3, + "explanation": "In a sunspot minimum the higher HF bands open less reliably, while 20 m often remains the best daily long-distance band. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH202", "confidence": 8 }, "AH203": { - "revision": 1, + "revision": 2, "explanation": "At night the lower HF bands suffer less D-region absorption, making 160, 80 and 40 m the best choices among the options.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH203", "confidence": 8 }, "AH204": { - "revision": 1, + "revision": 2, "explanation": "The F2 critical frequency is defined for vertical incidence: it is the highest frequency still returned by F2 when sent straight upward.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_muf_luf_2.html#AH204", "confidence": 8 }, "AH205": { - "revision": 1, + "revision": 2, "explanation": "At 90 degree incidence the path is vertical, so the maximum returned frequency equals the critical frequency, here 12 MHz.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_muf_luf_2.html#AH205", "confidence": 8 }, "AH206": { - "revision": 1, - "explanation": "MUF literally means maximum usable frequency: the highest frequency that can still support the specified ionospheric path.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "revision": 2, + "explanation": "MUF literally means maximum usable frequency: the highest frequency that can still support the specified ionospheric path. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_muf_luf_2.html#AH206", "confidence": 8 }, "AH207": { - "revision": 1, + "revision": 2, "explanation": "For a given path, MUF is the top of the usable range; above it the wave penetrates the ionosphere instead of returning.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_muf_luf_2.html#AH207", "confidence": 8 }, "AH208": { - "revision": 1, + "revision": 2, "explanation": "Oblique incidence effectively lengthens the path through the ionized region, so the usable frequency rises above the vertical critical frequency as the angle becomes flatter.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_muf_luf_2.html#AH208", "confidence": 8 }, "AH209": { - "revision": 1, - "explanation": "Using $MUF = f_k/sin(45°)$ gives about 4.2 MHz; the optimum working frequency is about 85% of MUF, or 3.6 MHz.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "revision": 2, + "explanation": "Using $MUF = f_k/sin(45°)$ gives about 4.2 MHz; the optimum working frequency is about 85% of MUF, or 3.6 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_muf_luf_2.html#AH209", "confidence": 8 }, "AH210": { - "revision": 1, + "revision": 2, "explanation": "LUF is the lower edge of the usable range: below it, absorption and noise make the sky-wave path unusable.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_muf_luf_2.html#AH210", "confidence": 8 }, "AH211": { - "revision": 1, + "revision": 2, "explanation": "If the LUF is 6 MHz, frequencies below 6 MHz are not considered usable for that sky-wave path under those conditions.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_muf_luf_2.html#AH211", "confidence": 8 }, "AH212": { - "revision": 1, + "revision": 2, "explanation": "Skip distance is set by geometry, ionospheric height/refraction and radiation angle; changing transmitter power affects strength, not where the ray returns.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_sprungdistanz_2.html#AH212", "confidence": 8 }, "AH213": { - "revision": 1, + "revision": 2, "explanation": "A single F2-hop can span several thousand kilometres because F2 is high; the usual rule of thumb is about 4000 km maximum.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_sprungdistanz_2.html#AH213", "confidence": 8 }, "AH214": { - "revision": 1, + "revision": 2, "explanation": "The E region is lower than F2, so a single hop returns sooner and covers only about 2200 km at most.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_sporadic_e_3.html#AH214", "confidence": 8 }, "AH215": { - "revision": 1, + "revision": 2, "explanation": "The nearby station lies beyond the ground wave but before the first sky-wave return point, so it is in the skip zone.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_tote_zone_2.html#AH215", "confidence": 8 }, "AH216": { - "revision": 1, + "revision": 2, "explanation": "The long path is the great-circle direction opposite the short path, so the beam heading differs by 180 degrees.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_langer_kurzer_weg_2.html#AH216", "confidence": 8 }, "AH217": { - "revision": 1, + "revision": 2, "explanation": "Long path is short-path azimuth plus 180 degrees modulo 360; 38 degrees becomes 218 degrees.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_langer_kurzer_weg_2.html#AH217", "confidence": 8 }, "AH218": { - "revision": 1, + "revision": 2, "explanation": "Long path is the reciprocal heading: 231 degrees plus 180 degrees wraps to 51 degrees.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_langer_kurzer_weg_2.html#AH218", "confidence": 8 }, "AH219": { - "revision": 1, + "revision": 2, "explanation": "Ionospheric refraction occurs in a magnetized, non-uniform plasma, so wave polarization is rotated and changed during sky-wave propagation.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH219", "confidence": 8 }, "AH220": { - "revision": 1, + "revision": 2, "explanation": "Sporadic-E creates intense E-region patches that return higher HF signals closer to the transmitter, shrinking or removing the skip zone.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_sporadic_e_3.html#AH220", "confidence": 8 }, "AH221": { - "revision": 1, + "revision": 2, "explanation": "Solar flares increase UV and X-ray ionization especially in the D region, and D-region absorption can wipe out HF sky-wave propagation.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_ionosphaere_3.html#AH221", "confidence": 8 }, "AH222": { - "revision": 1, + "revision": 2, "explanation": "Two paths arrive with different phases and delays; their superposition produces constructive and destructive interference.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_mehrwegeausbreitung.html#AH222", "confidence": 8 }, "AH223": { - "revision": 1, + "revision": 2, "explanation": "Backscatter signals return from irregular ionospheric regions, so their field strength fluctuates rapidly and irregularly.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_scatter.html#AH223", "confidence": 8 }, "AH301": { - "revision": 1, + "revision": 2, "explanation": "Sporadic-E propagation comes from small, strongly ionized E-region patches that can refract VHF signals.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_sporadic_e_3.html#AH301", "confidence": 8 }, "AH302": { - "revision": 1, + "revision": 2, "explanation": "Auroral ionization occurs at high geomagnetic latitudes, mainly in the E-region height range near the poles.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_aurora_2.html#AH302", "confidence": 8 }, "AH303": { - "revision": 1, + "revision": 2, "explanation": "Aurora is driven by charged solar particles guided into the polar atmosphere by Earth's magnetic field.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_aurora_2.html#AH303", "confidence": 8 }, "AH304": { - "revision": 1, + "revision": 2, "explanation": "The auroral zone becomes strongly ionized, and those irregular ionized regions can reflect or scatter VHF and UHF signals.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_aurora_2.html#AH304", "confidence": 8 }, "AH305": { - "revision": 1, + "revision": 2, "explanation": "An aurora contact on 2 m means the VHF signal was scattered or reflected by ionized auroral regions near the polar zone.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_aurora_2.html#AH305", "confidence": 8 }, "AH306": { - "revision": 1, + "revision": 2, "explanation": "From Europe the auroral oval is generally to the north, so the VHF antenna is pointed north for aurora operation.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_aurora_2.html#AH306", "confidence": 8 }, "AH307": { - "revision": 1, + "revision": 2, "explanation": "Aurora heavily distorts wide voice modes; CW remains readable because it is narrow and robust against the fluttery tone.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_aurora_2.html#AH307", "confidence": 8 }, "AH308": { - "revision": 1, + "revision": 2, "explanation": "Auroral scattering causes rapid Doppler and multipath changes, giving CW a rough, fluttering, buzzy tone.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_aurora_2.html#AH308", "confidence": 8 }, "AH309": { - "revision": 1, + "revision": 2, "explanation": "Tropospheric inversion layers can form ducts that guide VHF/UHF signals beyond the normal radio horizon.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_troposphaere_3.html#AH309", "confidence": 8 }, "AH310": { - "revision": 1, + "revision": 2, "explanation": "Aircraft scatter uses aircraft bodies as temporary reflectors for VHF, UHF or SHF signals beyond line of sight.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_scatter.html#AH310", "confidence": 8 }, "AH311": { - "revision": 1, + "revision": 2, "explanation": "Rainscatter is microwave scattering from rain and storm cells, most useful at short wavelengths such as the 3 cm band.", - "source": "https://50ohm.de/future/NEA_slide_nea_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_scatter.html#AH311", "confidence": 8 }, "AI101": { - "revision": 1, + "revision": 2, "explanation": "Voltage is measured in parallel with the PA input, while current is measured in series with the supply path, so the voltmeter and ammeter go at those positions.", - "source": "https://50ohm.de/EA_slide_ea_strom_spannung_widerstand_leistung_energie.html", + "source": "https://50ohm.de/NEA_strom_spannung_messung_3.html#AI101", "confidence": 8 }, "AI102": { - "revision": 1, + "revision": 2, "explanation": "An ammeter must be inserted in series; the instruments located in series paths are the current meters in the drawing.", - "source": "https://50ohm.de/EA_slide_ea_strom_spannung_widerstand_leistung_energie.html", + "source": "https://50ohm.de/NEA_strom_spannung_messung_3.html#AI102", "confidence": 8 }, "AI103": { - "revision": 1, + "revision": 2, "explanation": "Power is $U \\cdot I$; if both readings are 95% of true value, measured power is $0.95 \\cdot 0.95 = 0.9025$, or 9.75% low.", - "source": "https://50ohm.de/EA_slide_ea_strom_spannung_widerstand_leistung_energie.html", + "source": "https://50ohm.de/NEA_strom_spannung_messung_3.html#AI103", "confidence": 8 }, "AI104": { - "revision": 1, - "explanation": "The meter input current is $I = U/R = 0.5 V / 10 MOhm = 50 nA$.", - "source": "https://50ohm.de/EA_slide_ea_strom_spannung_widerstand_leistung_energie.html", + "revision": 3, + "explanation": "The meter input current is $I = U/R = 0.5 V / 10 MOhm = 50 nA$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_strom_spannung_messung_3.html#AI104", "confidence": 8 }, "AI105": { - "revision": 1, + "revision": 2, "explanation": "A thermal power sensor converts RF heating into a measurement, so it reads true effective power over a wide frequency range into the GHz region.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_wechselstrom_leistung.html#AI105", "confidence": 8 }, "AI201": { - "revision": 1, + "revision": 2, "explanation": "A VNA sweeps a known RF signal into the device under test and measures amplitude and phase of the response, deriving impedance, phase and SWR curves.", - "source": "https://50ohm.de/A_vna_2.html", + "source": "https://50ohm.de/NEA_vna_2.html#AI201", "confidence": 8 }, "AI202": { - "revision": 1, + "revision": 2, "explanation": "A trap is a resonant circuit; a VNA can sweep it and show the resonance directly from impedance or reflection behaviour.", - "source": "https://50ohm.de/A_vna_2.html", + "source": "https://50ohm.de/NEA_vna_2.html#AI202", "confidence": 8 }, "AI203": { - "revision": 1, + "revision": 2, "explanation": "A VNA is suited to HF resonant circuits because it measures the frequency-dependent impedance or transmission response across a sweep.", - "source": "https://50ohm.de/A_vna_2.html", + "source": "https://50ohm.de/NEA_vna_2.html#AI203", "confidence": 8 }, "AI204": { - "revision": 1, + "revision": 2, "explanation": "In complex impedance, negative $jX$ is capacitive reactance; the real part remains the 54 ohm resistance.", - "source": "https://50ohm.de/A_vna_2.html", + "source": "https://50ohm.de/NEA_vna_2.html#AI204", "confidence": 8 }, "AI205": { - "revision": 1, + "revision": 2, "explanation": "R = 50 ohm and jX = 0 means a purely resistive 50 ohm antenna impedance, matching a normal 50 ohm VHF transmitter output.", - "source": "https://50ohm.de/A_vna_2.html", + "source": "https://50ohm.de/NEA_vna_2.html#AI205", "confidence": 8 }, "AI206": { - "revision": 1, + "revision": 2, "explanation": "Positive $jX$ denotes inductive reactance, while R is the ohmic part of the impedance.", - "source": "https://50ohm.de/A_vna_2.html", + "source": "https://50ohm.de/NEA_vna_2.html#AI206", "confidence": 8 }, "AI207": { - "revision": 1, + "revision": 2, "explanation": "The shown resonance is below the target band; shortening a dipole raises its resonant frequency toward 80 m.", - "source": "https://50ohm.de/A_vna_2.html", + "source": "https://50ohm.de/NEA_vna_2.html#AI207", "confidence": 8 }, "AI208": { - "revision": 1, + "revision": 2, "explanation": "The shown resonance is above the target band; lengthening both dipole ends lowers the resonant frequency into 80 m.", - "source": "https://50ohm.de/A_vna_2.html", + "source": "https://50ohm.de/NEA_vna_2.html#AI208", "confidence": 8 }, "AI301": { - "revision": 1, + "revision": 2, "explanation": "An oscilloscope displays voltage versus time, so it is the instrument for checking waveform shape.", - "source": "https://50ohm.de/EA_oszilloskop_2.html", + "source": "https://50ohm.de/NEA_oszilloskop_2.html#AI301", "confidence": 8 }, "AI302": { - "revision": 1, + "revision": 2, "explanation": "A trigger starts each sweep at the same signal condition, making a repetitive waveform stand still on the display.", - "source": "https://50ohm.de/EA_oszilloskop_2.html", + "source": "https://50ohm.de/NEA_oszilloskop_2.html#AI302", "confidence": 8 }, "AI303": { - "revision": 1, + "revision": 2, "explanation": "Pulse width is conventionally measured between the points where the waveform crosses 50% of its peak amplitude.", - "source": "https://50ohm.de/EA_oszilloskop_2.html", + "source": "https://50ohm.de/NEA_oszilloskop_2.html#AI303", "confidence": 8 }, "AI304": { - "revision": 1, + "revision": 2, "explanation": "The RF envelope is a time-varying waveform; a sufficiently broadband oscilloscope can display that envelope directly.", - "source": "https://50ohm.de/EA_oszilloskop_2.html", + "source": "https://50ohm.de/NEA_ssb_3.html#AI304", "confidence": 8 }, "AI305": { - "revision": 1, - "explanation": "From the trace the peak voltage is 100 V; $P_{PEP} = (100/sqrt(2))^2 / 50$ gives 100 W.", - "source": "https://50ohm.de/EA_oszilloskop_2.html", + "revision": 3, + "explanation": "From the trace the peak voltage is 100 V; $P_{PEP} = (100/sqrt(2))^2 / 50$ gives 100 W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ssb_3.html#AI305", "confidence": 8 }, "AI306": { - "revision": 1, - "explanation": "A 10:1 probe means the real peak voltage is ten times the displayed value; $P_{PEP} = (60/sqrt(2))^2 / 50$ gives 36 W.", - "source": "https://50ohm.de/EA_oszilloskop_2.html", + "revision": 3, + "explanation": "A 10:1 probe means the real peak voltage is ten times the displayed value; $P_{PEP} = (60/sqrt(2))^2 / 50$ gives 36 W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ssb_3.html#AI306", "confidence": 8 }, "AI401": { - "revision": 1, - "explanation": "An SWR meter uses directional couplers to sample forward and reflected line voltages and compares them.", - "source": "https://50ohm.de/A_swr_meter_2.html", + "revision": 2, + "explanation": "An SWR meter uses directional couplers to sample forward and reflected line voltages and compares them. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_swr_meter_2.html#AI401", "confidence": 8 }, "AI402": { - "revision": 1, + "revision": 2, "explanation": "The two directional detector branches for forward and reverse power identify the circuit as an SWR meter.", - "source": "https://50ohm.de/A_swr_meter_2.html", + "source": "https://50ohm.de/NEA_swr_meter_2.html#AI402", "confidence": 8 }, "AI403": { - "revision": 1, + "revision": 2, "explanation": "For a purely resistive mismatch, SWR is the impedance ratio; $150/50 = 3$.", - "source": "https://50ohm.de/A_swr_meter_2.html", + "source": "https://50ohm.de/NEA_swr_meter_2.html#AI403", "confidence": 8 }, "AI501": { - "revision": 1, + "revision": 2, "explanation": "A modulated carrier moves or varies around the carrier frequency, so an unmodulated carrier gives the cleanest frequency-counter reading.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_frequenzmessung_2.html#AI501", "confidence": 8 }, "AI502": { - "revision": 1, + "revision": 2, "explanation": "A CW transmitter emits a steady RF carrier, and with suitable attenuation that carrier can be measured safely by a frequency counter.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_frequenzmessung_2.html#AI502", "confidence": 8 }, "AI503": { - "revision": 1, + "revision": 2, "explanation": "A frequency counter is the direct instrument for carrier frequency, and FM modulation should be absent to avoid measurement variation.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_frequenzmessung_2.html#AI503", "confidence": 8 }, "AI504": { - "revision": 1, + "revision": 2, "explanation": "The counter accuracy ultimately follows its timebase; stabilizing the main oscillator improves the frequency measurement.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_frequenzmessung_2.html#AI504", "confidence": 8 }, "AI505": { - "revision": 1, + "revision": 2, "explanation": "A longer gate time counts more cycles, so the least significant count represents a smaller frequency increment and resolution improves.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_frequenzmessung_2.html#AI505", "confidence": 8 }, "AI506": { - "revision": 1, - "explanation": "0.01% is $10^{-4}$; $29 MHz \\cdot 10^{-4} = 2900 Hz$.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "revision": 3, + "explanation": "0.01% is $10^{-4}$; $29 MHz \\cdot 10^{-4} = 2900 Hz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzgenauigkeit.html#AI506", "confidence": 8 }, "AI507": { - "revision": 1, - "explanation": "0.00001% is $10^{-7}$; $14100 kHz \\cdot 10^{-7}$ gives a maximum error of 1.410 Hz.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "revision": 2, + "explanation": "0.00001% is $10^{-7}$; $14100 kHz \\cdot 10^{-7}$ gives a maximum error of 1.410 Hz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzgenauigkeit.html#AI507", "confidence": 8 }, "AI508": { - "revision": 1, - "explanation": "One ppm is one part in a million; at 100 MHz that is 100 Hz.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "revision": 2, + "explanation": "One ppm is one part in a million; at 100 MHz that is 100 Hz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzgenauigkeit.html#AI508", "confidence": 8 }, "AI509": { - "revision": 1, - "explanation": "10 ppm of 145 MHz is 1450 Hz, so the counter may read 145 MHz plus or minus 0.00145 MHz.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "revision": 3, + "explanation": "10 ppm of 145 MHz is 1450 Hz, so the counter may read 145 MHz plus or minus 0.00145 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzgenauigkeit.html#AI509", "confidence": 8 }, "AI510": { - "revision": 1, - "explanation": "Protecting the 144.400 MHz beacon edge needs room for 2.7 kHz USB audio plus 1 ppm frequency error of 144 Hz, totaling 2.844 kHz below the edge.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "revision": 3, + "explanation": "Protecting the 144.400 MHz beacon edge needs room for 2.7 kHz USB audio plus 1 ppm frequency error of 144 Hz, totaling 2.844 kHz below the edge. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzgenauigkeit.html#AI510", "confidence": 8 }, "AI511": { - "revision": 1, + "revision": 2, "explanation": "A GPS-disciplined generator or OCXO provides a much more accurate reference than an ordinary LC or RC oscillator.", - "source": "https://50ohm.de/A_slide_a_empfaenger.html", + "source": "https://50ohm.de/NEA_frequenzmessung_2.html#AI511", "confidence": 8 }, "AI601": { - "revision": 1, - "explanation": "The resistor network uses 48 one-watt resistors to obtain about 50 ohms while sharing dissipation, so the continuous rating is 48 W.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 3, + "explanation": "The resistor network uses 48 one-watt resistors to obtain about 50 ohms while sharing dissipation, so the continuous rating is 48 W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_dummy_load_2.html#AI601", "confidence": 8 }, "AI602": { - "revision": 1, + "revision": 2, "explanation": "A peak rectifier on a dummy load samples RF voltage; with the load resistance known, that voltage gives RF power indirectly.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_dummy_load_2.html#AI602", "confidence": 8 }, "AI603": { - "revision": 1, + "revision": 2, "explanation": "A 5 ohm tap provides a reduced RF voltage sample, which can be read with a DMM through an HF probe to estimate output power.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_dummy_load_2.html#AI603", "confidence": 8 }, "AI604": { - "revision": 1, + "revision": 2, "explanation": "The diode-capacitor probe rectifies RF into a DC indication, useful as a simple measuring head while aligning RF circuits.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_sender_messungen.html#AI604", "confidence": 8 }, "AI605": { - "revision": 1, + "revision": 2, "explanation": "The diode, capacitor and high-impedance DC output are the standard structure of an RF probe.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_sender_messungen.html#AI605", "confidence": 8 }, "AI606": { - "revision": 1, - "explanation": "Correcting the 15.3 V reading for the Schottky drop gives the sampled RF peak; scaling from the 5 ohm tap to the 50 ohm load yields about 60 W.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 2, + "explanation": "Correcting the 15.3 V reading for the Schottky drop gives the sampled RF peak; scaling from the 5 ohm tap to the 50 ohm load yields about 60 W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_sender_messungen.html#AI606", "confidence": 8 }, "AI607": { - "revision": 1, - "explanation": "The detector voltage plus Schottky drop gives the RF peak at the measurement point; applying $P = U_{rms}^2/R$ gives roughly 600 mW.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 2, + "explanation": "The detector voltage plus Schottky drop gives the RF peak at the measurement point; applying $P = U_{rms}^2/R$ gives roughly 600 mW. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_sender_messungen.html#AI607", "confidence": 8 }, "AI608": { - "revision": 1, + "revision": 2, "explanation": "The circuit terminates the RF path and rectifies a known sample voltage, so it is a measuring head for RF power.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_sender_messungen.html#AI608", "confidence": 8 }, "AI609": { - "revision": 1, - "explanation": "The measuring head is not rated for the full expected 15 W directly; a 20 dB, 20 W attenuator reduces both level and risk.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 3, + "explanation": "The measuring head is not rated for the full expected 15 W directly; a 20 dB, 20 W attenuator reduces both level and risk. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_sender_messungen.html#AI609", "confidence": 8 }, "AI610": { - "revision": 1, - "explanation": "For 1 W into 50 ohms, $U_{rms}=sqrt(50)$ and peak voltage is about 10 V; the divider and diode drop leave about 4.8 V DC at the output.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 2, + "explanation": "For 1 W into 50 ohms, $U_{rms}=sqrt(50)$ and peak voltage is about 10 V; the divider and diode drop leave about 4.8 V DC at the output. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_sender_messungen.html#AI610", "confidence": 8 }, "AI611": { - "revision": 1, - "explanation": "Add the silicon diode drop to the DC reading to recover peak RF voltage, convert to RMS, then use $P=U^2/R$ with 54.1 ohms to get about 9.7 W.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 2, + "explanation": "Add the silicon diode drop to the DC reading to recover peak RF voltage, convert to RMS, then use $P=U^2/R$ with 54.1 ohms to get about 9.7 W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_sender_messungen.html#AI611", "confidence": 8 }, "AI612": { - "revision": 1, - "explanation": "Detector diodes, resistors and layout introduce systematic errors, so accurate RF power readings require calibration correction values.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 2, + "explanation": "Detector diodes, resistors and layout introduce systematic errors, so accurate RF power readings require calibration correction values. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_sender_messungen.html#AI612", "confidence": 8 }, "AI613": { - "revision": 1, + "revision": 2, "explanation": "The simple detector and meter respond to induced RF voltage without a direct connection, which is the function of a field-strength indicator.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_sender_messungen.html#AI613", "confidence": 8 }, "AI614": { - "revision": 1, + "revision": 2, "explanation": "A spectrum analyzer displays signal amplitude versus frequency, so it can measure the amplitudes of individual harmonics.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_nicht_sinus_signale.html#AI614", "confidence": 8 }, "AI615": { - "revision": 1, + "revision": 2, "explanation": "Harmonics appear as separate frequency components above the fundamental, which a spectrum analyzer is designed to reveal.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_nicht_sinus_signale.html#AI615", "confidence": 8 }, "AJ101": { - "revision": 1, + "revision": 2, "explanation": "Using only the power needed for reliable communication reduces unnecessary field strength at other receivers and therefore lowers interference risk.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ101", "confidence": 8 }, "AJ102": { - "revision": 1, + "revision": 2, "explanation": "An RF ground is useful only if it gives RF current a low-impedance return path at the operating frequency.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ102", "confidence": 8 }, "AJ103": { - "revision": 1, + "revision": 2, "explanation": "A grounded metal enclosure shields the receiver circuitry from external RF fields and reduces direct pickup by the board.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ103", "confidence": 8 }, "AJ104": { - "revision": 1, + "revision": 2, "explanation": "A tuner improves the match and filters suppress unwanted RF paths, both reducing unintended radiation from the antenna system.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ104", "confidence": 8 }, "AJ105": { - "revision": 1, + "revision": 2, "explanation": "Direct radiation into an IF stage bypasses the intended front-end selectivity; this direct pickup is called Direkteinstrahlung.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ105", "confidence": 8 }, "AJ106": { - "revision": 1, + "revision": 2, "explanation": "A transistor base-emitter junction behaves like a diode, so strong RF can be rectified there into audible interference.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ106", "confidence": 8 }, "AJ107": { - "revision": 1, + "revision": 2, "explanation": "SSB and CW have strong amplitude changes; weakly immune audio amplifiers can demodulate those changes into audible signals.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ107", "confidence": 8 }, "AJ108": { - "revision": 1, + "revision": 2, "explanation": "A broadband, unselective TV preamplifier has little rejection of nearby strong RF, so overload from a close transmitter is likely.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ108", "confidence": 8 }, "AJ109": { - "revision": 1, + "revision": 2, "explanation": "A very strong 432 MHz signal aimed at the TV antenna can overload the receiver front end even if it is not on the wanted TV channel.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ109", "confidence": 8 }, "AJ110": { - "revision": 1, + "revision": 2, "explanation": "A nearby VHF transmitter can drive the DAB receiver input beyond its linear range, causing overload rather than a true harmonic problem.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ110", "confidence": 8 }, "AJ111": { - "revision": 1, + "revision": 2, "explanation": "Digital receivers often conceal errors until correction fails; then the audio becomes noisy or mutes instead of fading smoothly.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ111", "confidence": 8 }, "AJ112": { - "revision": 1, + "revision": 2, "explanation": "A high-pass at the antenna blocks HF signals below the broadcast bands, while ferrite chokes suppress common-mode RF on every attached lead.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ112", "confidence": 8 }, "AJ113": { - "revision": 1, + "revision": 2, "explanation": "DVB-T2 starts far above 144 MHz, so a high-pass around 460 MHz rejects the 2 m transmitter while passing TV signals.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ113", "confidence": 8 }, "AJ114": { - "revision": 1, + "revision": 2, "explanation": "A TV high-pass should reject the interference but add little loss in the wanted band; more than a few dB would noticeably weaken reception.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ114", "confidence": 8 }, "AJ115": { - "revision": 1, + "revision": 2, "explanation": "An RF isolation transformer can interrupt common-mode currents in a receive antenna lead while passing the wanted differential signal.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_mantelwellen_2.html#AJ115", "confidence": 8 }, "AJ116": { - "revision": 1, + "revision": 2, "explanation": "If the TV is still disturbed with the antenna unplugged, the likely coupling path is mains or cabling, so a mains filter near the device is the first remedy.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ116", "confidence": 8 }, "AJ117": { - "revision": 1, + "revision": 2, "explanation": "Once the mains lead is identified as the coupling path, a mains filter is the targeted way to block RF entering through that path.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ117", "confidence": 8 }, "AJ118": { - "revision": 1, + "revision": 2, "explanation": "A mains RF filter combines series choking and capacitors to shunt common- and differential-mode RF before it enters the equipment.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ118", "confidence": 8 }, "AJ119": { - "revision": 1, + "revision": 2, "explanation": "Ceramic capacitors have low inductance at RF, so they bypass high-frequency voltages better than wound film or electrolytic capacitors.", - "source": "https://50ohm.de/A_stoerungen_elektronischer_geraete_2.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ119", "confidence": 8 }, "AJ201": { - "revision": 1, - "explanation": "The second harmonic is twice the fundamental: $2 \\cdot 3.730 MHz = 7.460 MHz$.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 3, + "explanation": "The second harmonic is twice the fundamental: $2 \\cdot 3.730 MHz = 7.460 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_nicht_sinus_signale.html#AJ201", "confidence": 8 }, "AJ202": { - "revision": 1, - "explanation": "The third harmonic is three times the fundamental: $3 \\cdot 7.050 MHz = 21.150 MHz$.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 3, + "explanation": "The third harmonic is three times the fundamental: $3 \\cdot 7.050 MHz = 21.150 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_nicht_sinus_signale.html#AJ202", "confidence": 8 }, "AJ203": { - "revision": 1, - "explanation": "The third overtone is the fourth harmonic, so $4 \\cdot 7.20 MHz = 28.80 MHz$.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 3, + "explanation": "The third overtone is the fourth harmonic, so $4 \\cdot 7.20 MHz = 28.80 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ203", "confidence": 8 }, "AJ204": { - "revision": 1, + "revision": 2, "explanation": "The third harmonic is $3 \\cdot 29.5 MHz = 88.5 MHz$, which lies in the FM broadcast band.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ204", "confidence": 8 }, "AJ205": { - "revision": 1, - "explanation": "Odd harmonics are 1st, 3rd, 5th, ...; the second odd harmonic is the 3rd, so $3 \\cdot 144.690 MHz = 434.070 MHz$.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 3, + "explanation": "Odd harmonics are 1st, 3rd, 5th, ...; the second odd harmonic is the 3rd, so $3 \\cdot 144.690 MHz = 434.070 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_nicht_sinus_signale.html#AJ205", "confidence": 8 }, "AJ206": { - "revision": 2, - "explanation": "Of the harmonics of 144.300 MHz, the 3rd at 432.900 MHz lands in the 70 cm amateur band and the 9th at 1298.700 MHz lands in the 23 cm band; other harmonics fall outside amateur allocations and don't disturb amateur operation.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "revision": 4, + "explanation": "Of the harmonics of 144.300 MHz, the 3rd at 432.900 MHz lands in the 70 cm amateur band and the 9th at 1298.700 MHz lands in the 23 cm band; other harmonics fall outside amateur allocations and don't disturb amateur operation. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_nicht_sinus_signale.html#AJ206", "confidence": 8 }, "AJ207": { - "revision": 1, + "revision": 2, "explanation": "Flattened or clipped waveform peaks indicate overdrive; clipping adds harmonic content to the transmitter output.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ207", "confidence": 8 }, "AJ208": { - "revision": 1, + "revision": 2, "explanation": "A single-band transmitter needs a low-pass-style output curve that passes the wanted band and attenuates higher harmonics.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ208", "confidence": 8 }, "AJ209": { - "revision": 1, + "revision": 2, "explanation": "For VHF, unwanted components can be both below and above the wanted channel, so a band-pass after the transmitter is appropriate.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ209", "confidence": 8 }, "AJ210": { - "revision": 1, + "revision": 2, "explanation": "A trap or notch circuit has high attenuation at one selected frequency, making it suitable for suppressing one specific harmonic.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ210", "confidence": 8 }, "AJ211": { - "revision": 1, + "revision": 2, "explanation": "A mixer produces sum, difference and other products; a band-pass passes only the wanted mixer product to the following stages.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ211", "confidence": 8 }, "AJ212": { - "revision": 1, + "revision": 2, "explanation": "Parasitic oscillations are self-oscillations of the circuit, not harmonics, so their frequencies need not have a fixed relation to the operating frequency.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_parasitaere_schwingungen.html#AJ212", "confidence": 8 }, "AJ213": { - "revision": 1, + "revision": 2, "explanation": "Small jumps in output while tuning are a classic symptom of a parasitic oscillation starting or stopping in the amplifier.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_parasitaere_schwingungen.html#AJ213", "confidence": 8 }, "AJ214": { - "revision": 1, + "revision": 2, "explanation": "RF chokes have stray capacitance, so their inductance and capacitance can form unintended self-resonances.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_2.html#AJ214", "confidence": 8 }, "AJ215": { - "revision": 1, + "revision": 2, "explanation": "Unwanted feedback from output to input can sustain oscillation; good input-output isolation reduces that loop gain.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_verstaerker_eigenschwingung.html#AJ215", "confidence": 8 }, "AJ216": { - "revision": 1, + "revision": 2, "explanation": "Shielding each RF stage reduces unintended capacitive and inductive coupling between stages, lowering the chance of self-oscillation.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_verstaerker_eigenschwingung.html#AJ216", "confidence": 8 }, "AJ217": { - "revision": 1, + "revision": 2, "explanation": "A ferrite bead adds lossy RF impedance in the transistor lead, damping VHF parasitic oscillation without affecting DC much.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_parasitaere_schwingungen.html#AJ217", "confidence": 8 }, "AJ218": { - "revision": 1, + "revision": 2, "explanation": "SSB has an amplitude-varying envelope and needs linear amplification; class C is nonlinear and would distort it badly.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_verstaerker_klasse.html#AJ218", "confidence": 8 }, "AJ219": { - "revision": 1, + "revision": 2, "explanation": "Excess microphone gain overdrives the SSB chain, broadening the signal and creating nearby intermodulation products known as splatter.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ219", "confidence": 8 }, "AJ220": { - "revision": 1, + "revision": 2, "explanation": "Abrupt CW keying has sharp envelope edges; sharp transitions contain wide sidebands heard as key clicks.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_symbolumschaltung_bandbreite.html#AJ220", "confidence": 8 }, "AJ221": { - "revision": 1, + "revision": 2, "explanation": "The least disturbing CW waveform has rounded rise and fall times, limiting high-frequency sidebands from keying transients.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_symbolumschaltung_bandbreite.html#AJ221", "confidence": 8 }, "AJ222": { - "revision": 1, + "revision": 2, "explanation": "A varying supply voltage changes the RF stage gain or amplitude, so it unintentionally amplitude-modulates the carrier.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ222", "confidence": 8 }, "AJ223": { - "revision": 1, + "revision": 2, "explanation": "NF ripple on the final-stage supply varies output amplitude at audio rate, which is unwanted AM on the transmitted signal.", - "source": "https://50ohm.de/future/NEA_slide_nea_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ223", "confidence": 8 }, "AJ224": { - "revision": 1, + "revision": 2, "explanation": "For 1.7 to 35 MHz, the cited unwanted-emission rule uses the 0.25 µW threshold and at least 40 dB attenuation relative to maximum PEP.", - "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ224", "confidence": 8 }, "AJ225": { - "revision": 1, + "revision": 2, "explanation": "For 50 to 1000 MHz, the stricter cited limit is at least 60 dB attenuation for unwanted emissions above 0.25 µW.", - "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_3.html#AJ225", "confidence": 8 }, "AK101": { - "revision": 1, + "revision": 2, "explanation": "In the near field, electric and magnetic fields are not locked to the fixed far-field phase and impedance relationship, so E and H cannot be simply converted.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "source": "https://50ohm.de/NEA_nahfeld.html#AK101", "confidence": 8 }, "AK102": { - "revision": 1, + "revision": 2, "explanation": "In the far field, E and H are tied by the wave impedance of the medium, about 377 ohms in free space.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "source": "https://50ohm.de/NEA_personenschutzabstand_3.html#AK102", "confidence": 8 }, "AK103": { - "revision": 1, - "explanation": "The simple distance formula assumes far-field behaviour; below roughly $lambda/(2 pi)$ or for electrically small antennas, measurement or near-field modelling is needed.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "revision": 2, + "explanation": "The simple distance formula assumes far-field behaviour; below roughly $lambda/(2 pi)$ or for electrically small antennas, measurement or near-field modelling is needed. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_nahfeld.html#AK103", "confidence": 8 }, "AK104": { - "revision": 1, - "explanation": "Feed-line loss reduces transmitter power before it reaches the antenna, so antenna input power is transmitter power multiplied by the loss factor.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "revision": 2, + "explanation": "Feed-line loss reduces transmitter power before it reaches the antenna, so antenna input power is transmitter power multiplied by the loss factor. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_personenschutzabstand_3.html#AK104", "confidence": 8 }, "AK105": { - "revision": 2, + "revision": 3, "explanation": "Safety distance scales as $d \\propto \\sqrt{P_{EIRP}}/E$. A 6 dB pattern attenuation cuts EIRP in that direction by a factor of 4, so the distance shrinks by $\\sqrt{4}=2$: 20 m becomes 10 m.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "source": "https://50ohm.de/NEA_personenschutzabstand_richtantennen.html#AK105", "confidence": 8 }, "AK106": { - "revision": 1, + "revision": 2, "explanation": "Use the person-protection distance formula with dipole gain and 100 W; solving against the 28 V/m limit gives about 2.50 m.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "source": "https://50ohm.de/NEA_naeherungsformel_2.html#AK106", "confidence": 8 }, "AK107": { - "revision": 1, - "explanation": "Rearranging the field-strength formula for power with 5 m distance, 28 V/m limit and 6 dBd gain gives roughly 100 W transmitter output.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "revision": 3, + "explanation": "Rearranging the field-strength formula for power with 5 m distance, 28 V/m limit and 6 dBd gain gives roughly 100 W transmitter output. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_personenschutzabstand_3.html#AK107", "confidence": 8 }, "AK108": { - "revision": 1, + "revision": 2, "explanation": "After 0.5 dB cable loss, the dipole ERP/EIRP term in the safety-distance formula gives about 4.10 m for the 28 V/m limit.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "source": "https://50ohm.de/NEA_naeherungsformel_2.html#AK108", "confidence": 8 }, "AK109": { - "revision": 1, + "revision": 2, "explanation": "The same distance formula scales with the square root of power; raising input power from 300 W to 700 W increases the distance to about 6.26 m.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "source": "https://50ohm.de/NEA_naeherungsformel_2.html#AK109", "confidence": 8 }, "AK110": { - "revision": 1, - "explanation": "Convert 11.5 dBd gain and 1.5 dB cable loss to linear factors, then apply $d = sqrt(30 P_{EIRP})/E$ to get about 6.86 m.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "revision": 2, + "explanation": "Convert 11.5 dBd gain and 1.5 dB cable loss to linear factors, then apply $d = sqrt(30 P_{EIRP})/E$ to get about 6.86 m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_naeherungsformel_2.html#AK110", "confidence": 8 }, "AK111": { - "revision": 1, + "revision": 2, "explanation": "With 100 W, 10.5 dBd gain and 1.5 dB cable loss, the far-field safety-distance formula against 28 V/m gives about 7.1 m.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "source": "https://50ohm.de/NEA_naeherungsformel_2.html#AK111", "confidence": 8 }, "AK112": { - "revision": 1, + "revision": 2, "explanation": "The 18 dBd dish gain minus 2 dB feed loss gives the EIRP term; using the 61 V/m limit yields about 4.6 m in the main beam.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "source": "https://50ohm.de/NEA_naeherungsformel_2.html#AK112", "confidence": 8 }, "AK113": { - "revision": 1, - "explanation": "12.15 dBi is a linear gain of about 16.4; $sqrt(30 \\cdot 250 W \\cdot 16.4)/30 m$ is about 11.7 V/m.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "revision": 3, + "explanation": "12.15 dBi is a linear gain of about 16.4; $sqrt(30 \\cdot 250 W \\cdot 16.4)/30 m$ is about 11.7 V/m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_personenschutzabstand_3.html#AK113", "confidence": 8 }, "AK114": { - "revision": 1, - "explanation": "A vertical dipole has about 2.15 dBi gain; applying the free-space field formula at 10 W and 10 m gives roughly 2.2 V/m.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "revision": 3, + "explanation": "A vertical dipole has about 2.15 dBi gain; applying the free-space field formula at 10 W and 10 m gives roughly 2.2 V/m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_personenschutzabstand_3.html#AK114", "confidence": 8 }, "AK115": { - "revision": 1, - "explanation": "Convert 100 W ERP to about 164 W EIRP, then $sqrt(30 \\cdot 164 W)/100 m$ gives about 0.7 V/m.", - "source": "https://50ohm.de/future/NEA_slide_nea_personenschutzabstand.html", + "revision": 3, + "explanation": "Convert 100 W ERP to about 164 W EIRP, then $sqrt(30 \\cdot 164 W)/100 m$ gives about 0.7 V/m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_personenschutzabstand_3.html#AK115", "confidence": 8 }, "AK201": { - "revision": 1, + "revision": 2, "explanation": "Charged power-supply capacitors can remain dangerous after unplugging; a suitably rated high-value resistor discharges them without a violent short-circuit current.", - "source": "https://50ohm.de/future/NEA_slide_nea_sicherheit.html", + "source": "https://50ohm.de/NEA_elektrische_geaete_oeffnen_2.html#AK201", "confidence": 8 }, "AK202": { - "revision": 1, + "revision": 2, "explanation": "Low-resistance bonding keeps exposed conductive parts at nearly the same potential, reducing touch-voltage risk to people.", - "source": "https://50ohm.de/future/NEA_slide_nea_sicherheit.html", + "source": "https://50ohm.de/NEA_schutzerdung_2.html#AK202", "confidence": 8 }, "AK203": { - "revision": 1, + "revision": 2, "explanation": "A separate earth lead near a quarter wavelength can resonate as an RF conductor, creating a voltage maximum at the equipment end.", - "source": "https://50ohm.de/future/NEA_slide_nea_sicherheit.html", + "source": "https://50ohm.de/NEA_schutzerdung_2.html#AK203", "confidence": 8 }, "AK204": { - "revision": 1, + "revision": 2, "explanation": "A transmitting antenna can have high RF voltage at current nodes or voltage maxima even with only a few watts, so touching it is unsafe.", - "source": "https://50ohm.de/future/NEA_slide_nea_sicherheit.html", + "source": "https://50ohm.de/NEA_antennen_beruehrung_2.html#AK204", "confidence": 8 }, "BA101": { - "revision": 2, + "revision": 3, "explanation": "DD4UQ spells D as Delta, U as Uniform and Q as Quebec; the traps are country-style words such as Denmark, Uruguay and Queen, which are not the ITU code words.", - "source": "https://life.itu.int/radioclub/rr/ap14.pdf", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#BA101", "confidence": 9 }, "BA102": { - "revision": 2, + "revision": 3, "explanation": "DK1KC uses Delta for D, Kilo for K and Charlie for C; Kilowatt, Denmark and Caesar are distractors, not ITU spelling-alphabet words.", - "source": "https://life.itu.int/radioclub/rr/ap14.pdf", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#BA102", "confidence": 9 }, "BA103": { - "revision": 2, + "revision": 3, "explanation": "DK5WP maps to Delta Kilo 5 Whiskey Papa; Kilowatt, William and Paris are common-looking substitutes but not the ITU words for K, W and P.", - "source": "https://life.itu.int/radioclub/rr/ap14.pdf", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#BA103", "confidence": 9 }, "BA104": { - "revision": 2, + "revision": 3, "explanation": "DL1FLO maps D/L/F/L/O to Delta, Lima, Foxtrot, Lima, Oscar; London, Florida and Oslo are distractors rather than ITU code words.", - "source": "https://life.itu.int/radioclub/rr/ap14.pdf", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#BA104", "confidence": 9 }, "BA105": { - "revision": 2, + "revision": 3, "explanation": "DL4YBZ uses Yankee, Bravo and Zulu for Y, B and Z; Ypsilon, Baker and Zebra are the non-ITU traps in the answer choices.", - "source": "https://life.itu.int/radioclub/rr/ap14.pdf", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#BA105", "confidence": 9 }, "BA106": { - "revision": 2, + "revision": 3, "explanation": "DM4EAX spells M as Mike, E as Echo, A as Alfa and X as X-ray; Madagascar, Ecuador and Amerika are distractors outside the ITU alphabet.", - "source": "https://life.itu.int/radioclub/rr/ap14.pdf", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#BA106", "confidence": 9 }, "BA107": { - "revision": 2, + "revision": 3, "explanation": "DN9RO/p uses Romeo and Oscar for R and O, while '/' is spoken as Stroke before the portable suffix; Radio, Oslo and Nordpol are distractors.", - "source": "https://life.itu.int/radioclub/rr/ap14.pdf", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#BA107", "confidence": 9 }, "BA108": { - "revision": 2, + "revision": 3, "explanation": "DN9STV maps S/T/V to Sierra, Tango and Victor; Santiago, Texas and Vulcano are plausible-sounding but not ITU code words.", - "source": "https://life.itu.int/radioclub/rr/ap14.pdf", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#BA108", "confidence": 9 }, "BA109": { - "revision": 2, + "revision": 3, "explanation": "DO9XJZ uses X-ray, Juliett and Zulu for X, J and Z; Xavier, Japan and Zebra are the distractor words.", - "source": "https://life.itu.int/radioclub/rr/ap14.pdf", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#BA109", "confidence": 9 }, "BA110": { - "revision": 2, + "revision": 3, "explanation": "IG9/DL4HR starts India Golf and uses Stroke for '/', with Hotel and Romeo at the end; Italy, Guatemala and Honolulu are distractors.", - "source": "https://life.itu.int/radioclub/rr/ap14.pdf", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#BA110", "confidence": 9 }, "BB101": { - "revision": 2, + "revision": 3, "explanation": "Abbreviations and Q groups compress common operating messages, so slow text modes carry more meaning per character and keep contacts concise.", - "source": "https://50ohm.de/NE_betriebliche_abkuerzungen.html", + "source": "https://50ohm.de/NEA_funkfernschreiben.html#BB101", "confidence": 8 }, "BB102": { - "revision": 2, + "revision": 3, "explanation": "CQ is the standard open invitation to any station, not a call to one named station.", - "source": "https://50ohm.de/NE_betriebliche_abkuerzungen.html", + "source": "https://50ohm.de/NEA_betriebsabwicklung.html#BB102", "confidence": 8 }, "BB103": { - "revision": 2, + "revision": 3, "explanation": "DX is operating shorthand for a distant station or long-distance contact; the distance threshold depends on band and propagation.", - "source": "https://50ohm.de/NE_betriebliche_abkuerzungen.html", + "source": "https://50ohm.de/NEA_dx.html#BB103", "confidence": 8 }, "BB104": { - "revision": 2, + "revision": 3, "explanation": "On VHF/UHF, normal local coverage is limited, so DX means stations well beyond local range, typically more than a few hundred kilometres away.", - "source": "https://50ohm.de/NE_betriebliche_abkuerzungen.html", + "source": "https://50ohm.de/NEA_dx.html#BB104", "confidence": 8 }, "BB105": { - "revision": 2, + "revision": 3, "explanation": "On 80 m at night, intercontinental propagation is plausible, so 'CQ DX' asks for stations from other continents rather than nearby stations.", - "source": "https://50ohm.de/NE_betriebliche_abkuerzungen.html", + "source": "https://50ohm.de/NEA_dx.html#BB105", "confidence": 8 }, "BB106": { - "revision": 2, + "revision": 3, "explanation": "TX, RX, and TRX follow the transmit/receive naming convention: transmitter, receiver, and a combined transceiver.", - "source": "https://50ohm.de/NE_betriebliche_abkuerzungen.html", + "source": "https://50ohm.de/NEA_betriebliche_abkuerzungen.html#BB106", "confidence": 8 }, "BB107": { - "revision": 2, + "revision": 3, "explanation": "CW names the continuous carrier used for Morse telegraphy; the information is keyed by interrupting or shifting that carrier.", - "source": "https://50ohm.de/NE_betriebliche_abkuerzungen.html", + "source": "https://50ohm.de/NEA_betriebliche_abkuerzungen.html#BB107", "confidence": 8 }, "BB108": { - "revision": 2, + "revision": 3, "explanation": "BK is the telegraphy break signal: it interrupts the current transmission or hands over informally without the full closing sequence.", - "source": "https://50ohm.de/NE_betriebliche_abkuerzungen.html", + "source": "https://50ohm.de/NEA_funkfernschreiben.html#BB108", "confidence": 8 }, "BB109": { - "revision": 2, + "revision": 3, "explanation": "K is the procedural invitation to transmit, so it marks that the other station may answer.", - "source": "https://50ohm.de/NE_betriebliche_abkuerzungen.html", + "source": "https://50ohm.de/NEA_funkfernschreiben.html#BB109", "confidence": 8 }, "BB110": { - "revision": 2, + "revision": 3, "explanation": "R at the start of a telegraphy over means 'received', confirming that the previous transmission was copied.", - "source": "https://50ohm.de/NE_betriebliche_abkuerzungen.html", + "source": "https://50ohm.de/NEA_funkfernschreiben.html#BB110", "confidence": 8 }, "BB201": { - "revision": 2, + "revision": 3, "explanation": "These Q groups encode common reception conditions: QRM is man-made interference, QRN is atmospheric noise, and QSB asks about fading.", - "source": "https://50ohm.de/N_q_schluessel.html", + "source": "https://50ohm.de/NEA_q_schluessel.html#BB201", "confidence": 8 }, "BB202": { - "revision": 2, + "revision": 3, "explanation": "With a question mark, QRO asks about increasing power, QSO asks about direct communication, and QRX asks when the next call should happen.", - "source": "https://50ohm.de/N_q_schluessel.html", + "source": "https://50ohm.de/NEA_q_schluessel.html#BB202", "confidence": 8 }, "BB203": { - "revision": 2, + "revision": 3, "explanation": "QRT orders stopping transmission, QRZ asks who is calling, and QSL? asks whether reception can be confirmed.", - "source": "https://50ohm.de/N_q_schluessel.html", + "source": "https://50ohm.de/NEA_q_schluessel.html#BB203", "confidence": 8 }, "BB204": { - "revision": 2, + "revision": 3, "explanation": "QRV states readiness, QRM? asks whether interference is present, and QTH gives a station location.", - "source": "https://50ohm.de/N_q_schluessel.html", + "source": "https://50ohm.de/NEA_q_schluessel.html#BB204", "confidence": 8 }, "BB205": { - "revision": 2, + "revision": 3, "explanation": "QRP is the operating signal for reducing transmitter power, so 'PSE QRP' is a polite request to turn it down.", - "source": "https://50ohm.de/N_q_schluessel.html", + "source": "https://50ohm.de/NEA_q_schluessel.html#BB205", "confidence": 8 }, "BB206": { - "revision": 2, + "revision": 3, "explanation": "QSY is the operating signal for changing frequency, so 'PSE QSY' asks you to move to another frequency.", - "source": "https://50ohm.de/N_q_schluessel.html", + "source": "https://50ohm.de/NEA_q_schluessel.html#BB206", "confidence": 8 }, "BC101": { - "revision": 1, - "explanation": "The 10 m amateur band is around 28 MHz, which lies in the 3-30 MHz HF shortwave range.", - "source": "ITU Radio Regulations, Article 2", + "revision": 2, + "explanation": "The 10 m amateur band is around 28 MHz, which lies in the 3-30 MHz HF shortwave range. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_frequenzspektrum.html#BC101", "confidence": 9 }, "BC102": { - "revision": 1, - "explanation": "The 2 m band is around 144-146 MHz, which lies in the 30-300 MHz VHF range.", - "source": "ITU Radio Regulations, Article 2", + "revision": 2, + "explanation": "The 2 m band is around 144-146 MHz, which lies in the 30-300 MHz VHF range. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_frequenzspektrum.html#BC102", "confidence": 9 }, "BC103": { - "revision": 1, - "explanation": "The 70 cm band is around 430-440 MHz, which lies in the 300-3000 MHz UHF range.", - "source": "ITU Radio Regulations, Article 2", + "revision": 2, + "explanation": "The 70 cm band is around 430-440 MHz, which lies in the 300-3000 MHz UHF range. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_frequenzspektrum.html#BC103", "confidence": 9 }, "BC104": { - "revision": 1, - "explanation": "HF is defined as 3-30 MHz; those wavelengths are roughly 100 m to 10 m, hence shortwave/KW.", - "source": "ITU Radio Regulations, Article 2", + "revision": 2, + "explanation": "HF is defined as 3-30 MHz; those wavelengths are roughly 100 m to 10 m, hence shortwave/KW. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_frequenzspektrum.html#BC104", "confidence": 9 }, "BC105": { - "revision": 1, - "explanation": "VHF is defined as 30-300 MHz; in German amateur practice this is the UKW range.", - "source": "ITU Radio Regulations, Article 2", + "revision": 2, + "explanation": "VHF is defined as 30-300 MHz; in German amateur practice this is the UKW range. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_frequenzspektrum.html#BC105", "confidence": 9 }, "BC106": { - "revision": 1, - "explanation": "UHF is defined as 300-3000 MHz; its wavelengths are in the decimetre range.", - "source": "ITU Radio Regulations, Article 2", + "revision": 2, + "explanation": "UHF is defined as 300-3000 MHz; its wavelengths are in the decimetre range. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_frequenzspektrum.html#BC106", "confidence": 9 }, "BC201": { - "revision": 1, - "explanation": "IARU band plans are coordination recommendations, not law, but following them prevents incompatible modes from crowding each other.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2021/06/hf_r1_bandplan.pdf", + "revision": 2, + "explanation": "IARU band plans are coordination recommendations, not law, but following them prevents incompatible modes from crowding each other. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan.html#BC201", "confidence": 7 }, "BC202": { - "revision": 1, - "explanation": "The HF band-plan convention uses lower sideband below 10 MHz, so 80 m normally uses LSB.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2021/06/hf_r1_bandplan.pdf", + "revision": 2, + "explanation": "The HF band-plan convention uses lower sideband below 10 MHz, so 80 m normally uses LSB. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_trxmodulation.html#BC202", "confidence": 7 }, "BC203": { - "revision": 1, - "explanation": "The HF band-plan convention uses upper sideband above 10 MHz, so 20 m normally uses USB.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2021/06/hf_r1_bandplan.pdf", + "revision": 2, + "explanation": "The HF band-plan convention uses upper sideband above 10 MHz, so 20 m normally uses USB. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_trxmodulation.html#BC203", "confidence": 7 }, "BC204": { - "revision": 1, - "explanation": "Band plans put narrow Morse activity at the lower edge of most bands, leaving wider modes farther up the band.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2021/06/hf_r1_bandplan.pdf", + "revision": 2, + "explanation": "Band plans put narrow Morse activity at the lower edge of most bands, leaving wider modes farther up the band. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan.html#BC204", "confidence": 7 }, "BC205": { - "revision": 1, - "explanation": "The Region 1 VHF plan marks 145.500 MHz as the 2 m FM calling frequency, so it is used for general FM calls.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "The Region 1 VHF plan marks 145.500 MHz as the 2 m FM calling frequency, so it is used for general FM calls. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_2m.html#BC205", "confidence": 7 }, "BC206": { - "revision": 1, - "explanation": "The Region 1 UHF plan marks 433.500 MHz as the 70 cm FM calling frequency, so it is used for general FM calls.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "The Region 1 UHF plan marks 433.500 MHz as the 70 cm FM calling frequency, so it is used for general FM calls. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_70cm.html#BC206", "confidence": 7 }, "BC207": { - "revision": 1, - "explanation": "The 2 m band plan lists 145.375 MHz for digital voice calling, separating it from analogue FM calling traffic.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "The 2 m band plan lists 145.375 MHz for digital voice calling, separating it from analogue FM calling traffic. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_2m.html#BC207", "confidence": 7 }, "BC208": { - "revision": 1, - "explanation": "The 70 cm band plan lists 433.450 MHz for digital voice calling, separating it from analogue FM calling traffic.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "The 70 cm band plan lists 433.450 MHz for digital voice calling, separating it from analogue FM calling traffic. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_70cm.html#BC208", "confidence": 7 }, "BC209": { - "revision": 1, - "explanation": "145.450 MHz falls in the 2 m FM simplex channel area, so it is suitable for an FM voice contact under the band plan.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "145.450 MHz falls in the 2 m FM simplex channel area, so it is suitable for an FM voice contact under the band plan. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_2m.html#BC209", "confidence": 7 }, "BC210": { - "revision": 1, - "explanation": "144.310 MHz sits near the 144.300 MHz SSB centre of activity, so it is appropriate for 2 m SSB voice.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "144.310 MHz sits near the 144.300 MHz SSB centre of activity, so it is appropriate for 2 m SSB voice. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_2m.html#BC210", "confidence": 7 }, "BC211": { - "revision": 1, - "explanation": "The 2 m band plan uses 144.300 MHz as the SSB centre of activity.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "The 2 m band plan uses 144.300 MHz as the SSB centre of activity. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_2m.html#BC211", "confidence": 7 }, "BC212": { - "revision": 1, - "explanation": "The 70 cm band plan uses 432.200 MHz as the SSB centre of activity.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "The 70 cm band plan uses 432.200 MHz as the SSB centre of activity. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_70cm.html#BC212", "confidence": 7 }, "BC213": { - "revision": 1, - "explanation": "144.075 MHz lies in the narrow Morse-preferred segment, so wider or keyboard digital modes should use their own segments.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "144.075 MHz lies in the narrow Morse-preferred segment, so wider or keyboard digital modes should use their own segments. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_2m.html#BC213", "confidence": 7 }, "BC214": { - "revision": 1, - "explanation": "Around 144.125 MHz the 2 m band plan is for Morse and narrow digital work, not local FM voice.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "Around 144.125 MHz the 2 m band plan is for Morse and narrow digital work, not local FM voice. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_2m.html#BC214", "confidence": 7 }, "BC215": { - "revision": 1, - "explanation": "Around 144.450 MHz the 2 m band plan reserves beacon use, so an ordinary local FM QSO would occupy the wrong segment.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "Around 144.450 MHz the 2 m band plan reserves beacon use, so an ordinary local FM QSO would occupy the wrong segment. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_2m.html#BC215", "confidence": 7 }, "BC216": { - "revision": 1, - "explanation": "The 145.500-145.5625 MHz FM simplex area is channelised for narrow FM, so keeping to about 12 kHz avoids adjacent-channel interference.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "The 145.500-145.5625 MHz FM simplex area is channelised for narrow FM, so keeping to about 12 kHz avoids adjacent-channel interference. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_fm.html#BC216", "confidence": 7 }, "BC217": { - "revision": 1, - "explanation": "145.600 MHz is in the 2 m repeater output area, so a direct local FM contact would interfere with repeater operation.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "145.600 MHz is in the 2 m repeater output area, so a direct local FM contact would interfere with repeater operation. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_2m.html#BC217", "confidence": 7 }, "BC218": { - "revision": 1, - "explanation": "145.800 MHz belongs to the 2 m space-communication segment, so it should be kept clear for satellite and other space contacts.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "145.800 MHz belongs to the 2 m space-communication segment, so it should be kept clear for satellite and other space contacts. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_2m.html#BC218", "confidence": 7 }, "BC219": { - "revision": 1, - "explanation": "432.040 MHz lies in the 70 cm Morse/narrow digital segment, so local FM voice would be the wrong bandwidth and mode there.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "432.040 MHz lies in the 70 cm Morse/narrow digital segment, so local FM voice would be the wrong bandwidth and mode there. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_70cm.html#BC219", "confidence": 7 }, "BC220": { - "revision": 1, - "explanation": "432.450 MHz is assigned to beacon activity in the 70 cm plan, so it should not be used for an ordinary local FM contact.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "432.450 MHz is assigned to beacon activity in the 70 cm plan, so it should not be used for an ordinary local FM contact. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_70cm.html#BC220", "confidence": 7 }, "BC221": { - "revision": 1, - "explanation": "435.500 MHz lies in the 70 cm satellite segment, so terrestrial local FM would risk interfering with satellite operation.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "435.500 MHz lies in the 70 cm satellite segment, so terrestrial local FM would risk interfering with satellite operation. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_70cm.html#BC221", "confidence": 7 }, "BC222": { - "revision": 1, - "explanation": "439.200 MHz is in the 70 cm repeater output area, so a direct local FM contact would occupy repeater spectrum.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "revision": 2, + "explanation": "439.200 MHz is in the 70 cm repeater output area, so a direct local FM contact would occupy repeater spectrum. Hilfsmittel: the IARU band plan reproduced in the official exam aids (Hilfsmittel) gives this directly, so it can be looked up in the exam rather than memorized.", + "source": "https://50ohm.de/NEA_iaru_bandplan_70cm.html#BC222", "confidence": 7 }, "BD101": { - "revision": 1, - "explanation": "German club-station call signs use zero in the numeral position; DA0ABC therefore identifies a club station.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__10.html", + "revision": 3, + "explanation": "German club-station call signs use zero in the numeral position; DA0ABC therefore identifies a club station. Hilfsmittel: the German call-sign plan (Rufzeichenplan) in the official exam aids (Hilfsmittel) lists which call-sign series belong to which class and use, so this is a lookup in the exam rather than a memory item.", + "source": "https://50ohm.de/NEA_klubstationen.html#BD101", "confidence": 9 }, "BD102": { - "revision": 1, - "explanation": "AFuV §16 allows BNetzA to permit special experimental or technical-scientific studies and to make that dependent on assigning another call sign.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "revision": 3, + "explanation": "AFuV §16 allows BNetzA to permit special experimental or technical-scientific studies and to make that dependent on assigning another call sign. Hilfsmittel: the German call-sign plan (Rufzeichenplan) in the official exam aids (Hilfsmittel) lists which call-sign series belong to which class and use, so this is a lookup in the exam rather than a memory item.", + "source": "https://50ohm.de/NEA_experimentelle_studien.html#BD102", "confidence": 10 }, "BD103": { - "revision": 1, - "explanation": "DL0 is in the German club-station pattern for class A, and the zero distinguishes it from person-bound DL1-DL9 calls.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__10.html", + "revision": 3, + "explanation": "DL0 is in the German club-station pattern for class A, and the zero distinguishes it from person-bound DL1-DL9 calls. Hilfsmittel: the German call-sign plan (Rufzeichenplan) in the official exam aids (Hilfsmittel) lists which call-sign series belong to which class and use, so this is a lookup in the exam rather than a memory item.", + "source": "https://50ohm.de/NEA_klubstationen.html#BD103", "confidence": 9 }, "BD104": { - "revision": 1, - "explanation": "In the German call-sign plan, DL1-DL9 with normal two- or three-letter suffixes are person-bound class A call signs.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__10.html", + "revision": 3, + "explanation": "In the German call-sign plan, DL1-DL9 with normal two- or three-letter suffixes are person-bound class A call signs. Hilfsmittel: the German call-sign plan (Rufzeichenplan) in the official exam aids (Hilfsmittel) lists which call-sign series belong to which class and use, so this is a lookup in the exam rather than a memory item.", + "source": "https://50ohm.de/NEA_persoenliche_rufzeichen.html#BD104", "confidence": 9 }, "BD105": { - "revision": 1, - "explanation": "The German call-sign plan assigns DN9 to person-bound class N call signs.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__10.html", + "revision": 3, + "explanation": "The German call-sign plan assigns DN9 to person-bound class N call signs. Hilfsmittel: the German call-sign plan (Rufzeichenplan) in the official exam aids (Hilfsmittel) lists which call-sign series belong to which class and use, so this is a lookup in the exam rather than a memory item.", + "source": "https://50ohm.de/NEA_persoenliche_rufzeichen.html#BD105", "confidence": 9 }, "BD106": { - "revision": 1, - "explanation": "The German call-sign plan assigns DO1-DO9 with normal suffixes to person-bound class E call signs.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__10.html", + "revision": 3, + "explanation": "The German call-sign plan assigns DO1-DO9 with normal suffixes to person-bound class E call signs. Hilfsmittel: the German call-sign plan (Rufzeichenplan) in the official exam aids (Hilfsmittel) lists which call-sign series belong to which class and use, so this is a lookup in the exam rather than a memory item.", + "source": "https://50ohm.de/NEA_persoenliche_rufzeichen.html#BD106", "confidence": 9 }, "BD107": { - "revision": 2, - "explanation": "DP0GVN is one of the German exterritorial class A station patterns; DP0 is used for special locations outside ordinary German territory.", - "source": "https://50ohm.de/NE_exterritoriale_stationen.html", + "revision": 4, + "explanation": "DP0GVN is one of the German exterritorial class A station patterns; DP0 is used for special locations outside ordinary German territory. Hilfsmittel: the German call-sign plan (Rufzeichenplan) in the official exam aids (Hilfsmittel) lists which call-sign series belong to which class and use, so this is a lookup in the exam rather than a memory item.", + "source": "https://50ohm.de/NEA_exterritoriale_stationen.html#BD107", "confidence": 8 }, "BD108": { - "revision": 2, - "explanation": "DP0POL follows the same exterritorial class A pattern as other German Antarctic or special-location stations.", - "source": "https://50ohm.de/NE_exterritoriale_stationen.html", + "revision": 4, + "explanation": "DP0POL follows the same exterritorial class A pattern as other German Antarctic or special-location stations. Hilfsmittel: the German call-sign plan (Rufzeichenplan) in the official exam aids (Hilfsmittel) lists which call-sign series belong to which class and use, so this is a lookup in the exam rather than a memory item.", + "source": "https://50ohm.de/NEA_exterritoriale_stationen.html#BD108", "confidence": 8 }, "BD109": { - "revision": 1, - "explanation": "Low-power transmitters for direction finding may identify with short MO-series markers instead of a normal amateur call sign.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__11.html", + "revision": 3, + "explanation": "Low-power transmitters for direction finding may identify with short MO-series markers instead of a normal amateur call sign. Hilfsmittel: the German call-sign plan (Rufzeichenplan) in the official exam aids (Hilfsmittel) lists which call-sign series belong to which class and use, so this is a lookup in the exam rather than a memory item.", + "source": "https://50ohm.de/NEA_ardf.html#BD109", "confidence": 9 }, "BD201": { - "revision": 2, - "explanation": "The suffix /am means aeronautical mobile: the station is operating from an aircraft.", - "source": "https://50ohm.de/NE_rufzeichenzusaetze.html", + "revision": 3, + "explanation": "The suffix /am means aeronautical mobile: the station is operating from an aircraft. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#BD201", "confidence": 8 }, "BD202": { - "revision": 1, - "explanation": "VE is a Canadian call-sign series, and /am adds that the station is being operated from an aircraft.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "revision": 2, + "explanation": "VE is a Canadian call-sign series, and /am adds that the station is being operated from an aircraft. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#BD202", "confidence": 9 }, "BD203": { - "revision": 2, - "explanation": "The suffix /m means mobile; for amateur operation that includes a station moving in a land vehicle.", - "source": "https://50ohm.de/NE_rufzeichenzusaetze.html", + "revision": 3, + "explanation": "The suffix /m means mobile; for amateur operation that includes a station moving in a land vehicle. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#BD203", "confidence": 8 }, "BD204": { - "revision": 2, - "explanation": "The suffix /m can also mark mobile operation on inland waterways, distinct from /mm on the high seas.", - "source": "https://50ohm.de/NE_rufzeichenzusaetze.html", + "revision": 3, + "explanation": "The suffix /m can also mark mobile operation on inland waterways, distinct from /mm on the high seas. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#BD204", "confidence": 8 }, "BD205": { - "revision": 2, - "explanation": "The suffix /mm means maritime mobile, so the station is aboard a vessel at sea rather than on land or inland water.", - "source": "https://50ohm.de/NE_rufzeichenzusaetze.html", + "revision": 3, + "explanation": "The suffix /mm means maritime mobile, so the station is aboard a vessel at sea rather than on land or inland water. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#BD205", "confidence": 8 }, "BD206": { - "revision": 1, - "explanation": "The suffix /p is used as extra information for portable or temporarily fixed operation.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__11.html", + "revision": 2, + "explanation": "The suffix /p is used as extra information for portable or temporarily fixed operation. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#BD206", "confidence": 9 }, "BD207": { - "revision": 1, - "explanation": "AFuV allows internationally customary suffixes but does not require /p for portable or temporary fixed operation in Germany.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__11.html", + "revision": 2, + "explanation": "AFuV allows internationally customary suffixes but does not require /p for portable or temporary fixed operation in Germany. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#BD207", "confidence": 9 }, "BD208": { - "revision": 1, - "explanation": "AFuV §11 names Remote for speech and /R for telegraphy or digital modes when marking remote operation.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__11.html", + "revision": 2, + "explanation": "AFuV §11 names Remote for speech and /R for telegraphy or digital modes when marking remote operation. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#BD208", "confidence": 10 }, "BD209": { - "revision": 1, - "explanation": "For training operation, AFuV §11 requires /Trainee in speech, so the trainee uses the instructor's call sign plus that suffix.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__11.html", + "revision": 2, + "explanation": "For training operation, AFuV §11 requires /Trainee in speech, so the trainee uses the instructor's call sign plus that suffix. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_ausbildungsfunk.html#BD209", "confidence": 10 }, "BD210": { - "revision": 1, - "explanation": "Training operation may use the club-station call sign, but AFuV §11 requires the training suffix /Trainee for speech or /T for telegraphy/digital modes.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__11.html", + "revision": 2, + "explanation": "Training operation may use the club-station call sign, but AFuV §11 requires the training suffix /Trainee for speech or /T for telegraphy/digital modes. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_ausbildungsrufzeichen.html#BD210", "confidence": 10 }, "BD211": { - "revision": 1, - "explanation": "For training in Morse or digital modes, AFuV §11 requires the short /T suffix on the instructor's call sign.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__11.html", + "revision": 2, + "explanation": "For training in Morse or digital modes, AFuV §11 requires the short /T suffix on the instructor's call sign. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_ausbildungsrufzeichen.html#BD211", "confidence": 10 }, "BD212": { - "revision": 1, - "explanation": "CEPT guest operation uses the visited country's prefix before the home call sign, so a UK G3MM station temporarily in Germany signs with DL/.", - "source": "https://docdb.cept.org/download/3321", + "revision": 2, + "explanation": "CEPT guest operation uses the visited country's prefix before the home call sign, so a UK G3MM station temporarily in Germany signs with DL/. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#BD212", "confidence": 9 }, "BD213": { - "revision": 1, - "explanation": "CEPT Novice guest operation in Switzerland uses the Swiss novice visitor prefix HB3 before the German class E call sign.", - "source": "https://docdb.cept.org/download/2768", + "revision": 2, + "explanation": "CEPT Novice guest operation in Switzerland uses the Swiss novice visitor prefix HB3 before the German class E call sign. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#BD213", "confidence": 9 }, "BD214": { - "revision": 1, - "explanation": "CEPT guest operation in Switzerland uses the Swiss HB9 prefix before the German class A call sign.", - "source": "https://docdb.cept.org/download/3321", + "revision": 2, + "explanation": "CEPT guest operation in Switzerland uses the Swiss HB9 prefix before the German class A call sign. Hilfsmittel: the list of internationally used call-sign suffixes in the official exam aids (Hilfsmittel, Rufzeichenplan) gives this directly — a lookup in the exam, not a memory item.", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#BD214", "confidence": 9 }, "BD301": { - "revision": 1, + "revision": 2, "explanation": "Unknown prefixes are a lookup item: the ITU call-sign allocation table, handbooks, and callbooks map prefix blocks to countries.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD301", "confidence": 9 }, "BD302": { - "revision": 1, + "revision": 2, "explanation": "ITU call-sign series split DA-DR to Germany, DS-DT to South Korea, and DU-DZ to the Philippines.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD302", "confidence": 9 }, "BD303": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps OE to Austria, ON to Belgium, and OK to Czechia.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD303", "confidence": 9 }, "BD304": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps OE to Austria, PA to the Netherlands, and SM to Sweden.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD304", "confidence": 9 }, "BD305": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps F to France, PA to the Netherlands, and SP to Poland.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD305", "confidence": 9 }, "BD306": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps SM to Sweden, SP to Poland, and ZS to South Africa.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD306", "confidence": 9 }, "BD307": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps 4X to Israel, F to France, and OZ to Denmark.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD307", "confidence": 9 }, "BD308": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps EA to Spain, EI to Ireland, EK to Armenia, EM to Ukraine, and ES to Estonia.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD308", "confidence": 9 }, "BD309": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps VE to Canada, VK to Australia, and PY to Brazil.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD309", "confidence": 9 }, "BD310": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps HB9 to Switzerland, EA to Spain, and ON to Belgium.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD310", "confidence": 9 }, "BD311": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps EA to Spain, LX to Luxembourg, and SP to Poland.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD311", "confidence": 9 }, "BD312": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps W to the United States, ZL to New Zealand, and LU to Argentina.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD312", "confidence": 9 }, "BD313": { - "revision": 1, + "revision": 2, "explanation": "The ITU prefix table maps BY to China, VE to Canada, and VK to Australia.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD313", "confidence": 9 }, "BD314": { - "revision": 1, + "revision": 2, "explanation": "F, HB9, OZ, and SP correspond to France, Switzerland, Denmark, and Poland, all neighbours of Germany.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD314", "confidence": 9 }, "BD315": { - "revision": 1, + "revision": 2, "explanation": "K and W are United States call-sign series, so K3LR, W3DZZ, and K4EAX are all US-style calls.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD315", "confidence": 9 }, "BD316": { - "revision": 1, + "revision": 2, "explanation": "W, VE, and XE identify the United States, Canada, and Mexico; all three are on North America.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD316", "confidence": 9 }, "BD317": { - "revision": 1, + "revision": 2, "explanation": "PY, CE, and LU identify Brazil, Chile, and Argentina, all in South America.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD317", "confidence": 9 }, "BD318": { - "revision": 1, + "revision": 2, "explanation": "BY, JA, and VU identify China, Japan, and India, all in Asia.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_internationale_landeskenner.html#BD318", "confidence": 9 }, "BE101": { - "revision": 1, + "revision": 2, "explanation": "A contact starts either as a general call, a directed call, or an answer to a call; in every case the own call sign identifies the transmitting station.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__11.html", + "source": "https://50ohm.de/NEA_betriebsabwicklung.html#BE101", "confidence": 9 }, "BE102": { - "revision": 2, + "revision": 3, "explanation": "Answering CQ first names the station being called, then gives your own call sign once, which makes both sides of the intended contact clear.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_betriebsabwicklung.html#BE102", "confidence": 8 }, "BE103": { - "revision": 2, + "revision": 3, "explanation": "A partial call containing your suffix is not enough certainty, so asking whether you were called avoids answering for another station.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_betriebsabwicklung.html#BE103", "confidence": 8 }, "BE104": { - "revision": 2, + "revision": 3, "explanation": "In English phone procedure, name the station you are calling first and then identify yourself with 'this is' plus your call sign.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_dx.html#BE104", "confidence": 8 }, "BE105": { - "revision": 2, + "revision": 3, "explanation": "A clear frequency may still be in use, so asking whether it is occupied before calling CQ reduces accidental interference.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_betriebsabwicklung.html#BE105", "confidence": 8 }, "BE106": { - "revision": 2, + "revision": 3, "explanation": "On higher HF bands, skip propagation can create a dead zone: you may not hear a nearby station that is nevertheless using the frequency.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_ionosphaere.html#BE106", "confidence": 8 }, "BE107": { - "revision": 1, + "revision": 2, "explanation": "145.500 MHz is a calling channel; after contact is made, moving by QSY keeps the calling channel available for others.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "source": "https://50ohm.de/NEA_q_schluessel.html#BE107", "confidence": 7 }, "BE108": { - "revision": 2, + "revision": 3, "explanation": "After your CQ contact ends, the original frequency should not become a queue; arranging QSY keeps the calling or working frequency usable.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_betriebsabwicklung.html#BE108", "confidence": 8 }, "BE109": { - "revision": 2, + "revision": 3, "explanation": "On 2 m and 70 cm, 'DX' means well beyond normal local range, so local or nearby stations should wait.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_dx.html#BE109", "confidence": 8 }, "BE110": { - "revision": 2, + "revision": 3, "explanation": "CQ VK/ZL is a directed CQ for Australia and New Zealand prefixes, so a non-VK/ZL station should not answer.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_dx.html#BE110", "confidence": 8 }, "BE111": { - "revision": 2, + "revision": 3, "explanation": "The Maidenhead locator encodes geographic position into grid fields and squares, giving a compact location reference for radio contacts.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_locator.html#BE111", "confidence": 8 }, "BE112": { - "revision": 2, + "revision": 3, "explanation": "A CW CQ repeats CQ and the own call sign, uses DE for 'from', and ends with K to invite replies.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_funkfernschreiben.html#BE112", "confidence": 8 }, "BE113": { - "revision": 2, + "revision": 3, "explanation": "CQ DL is a directed general call for German stations, and PSE K politely invites those stations to answer.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_dx.html#BE113", "confidence": 8 }, "BE114": { - "revision": 2, + "revision": 3, "explanation": "CQ DX on 20 m asks for distant intercontinental contacts; a European station should not answer a Swiss station's DX call.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_dx.html#BE114", "confidence": 8 }, "BE115": { - "revision": 2, + "revision": 3, "explanation": "QRZ? asks 'who is calling me?' and in a pile-up it is also used to invite the next callers.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_q_schluessel.html#BE115", "confidence": 8 }, "BE116": { - "revision": 2, + "revision": 3, "explanation": "CQ FD and TEST mark contest traffic for Field Day, and /P says the station is operating portable.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_contest.html#BE116", "confidence": 8 }, "BE117": { - "revision": 2, + "revision": 3, "explanation": "Matching or slowing down to the caller's Morse speed improves copy and avoids forcing the other operator beyond their receive speed.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_morsetelegrafie.html#BE117", "confidence": 8 }, "BE118": { - "revision": 2, + "revision": 3, "explanation": "Morse should be sent no faster than you can copy and adjusted to slower stations, because reliable exchange matters more than speed.", - "source": "https://50ohm.de/NE_betriebsabwicklung.html", + "source": "https://50ohm.de/NEA_morsetelegrafie.html#BE118", "confidence": 8 }, "BE201": { - "revision": 2, + "revision": 3, "explanation": "RST is a compact reception report, so it summarizes how well the signal can be read and, where relevant, its strength and tone.", - "source": "https://50ohm.de/N_rst.html", + "source": "https://50ohm.de/NEA_rst.html#BE201", "confidence": 8 }, "BE202": { - "revision": 2, + "revision": 3, "explanation": "The letters name the three report dimensions: Readability, Strength, and Tone.", - "source": "https://50ohm.de/N_rst.html", + "source": "https://50ohm.de/NEA_rst.html#BE202", "confidence": 8 }, "BE203": { - "revision": 2, + "revision": 3, "explanation": "The RST scale uses R 1-5 for readability, S 1-9 for signal strength, and T 1-9 for tone quality.", - "source": "https://50ohm.de/N_rst.html", + "source": "https://50ohm.de/NEA_rst.html#BE203", "confidence": 8 }, "BE204": { - "revision": 3, + "revision": 4, "explanation": "On the analogue S-meter, the needle indicates S5. For SSB phone the tone digit is omitted; clear copy gives R5, so the report is 55.", - "source": "https://50ohm.de/N_rst.html", + "source": "https://50ohm.de/NEA_rst.html#BE204", "confidence": 8 }, "BE205": { - "revision": 3, + "revision": 4, "explanation": "On the analogue S-meter, the needle indicates S9. For SSB phone the tone digit is omitted; clear copy gives R5, so the report is 59.", - "source": "https://50ohm.de/N_rst.html", + "source": "https://50ohm.de/NEA_rst.html#BE205", "confidence": 8 }, "BE206": { - "revision": 3, + "revision": 4, "explanation": "On the analogue S-meter, the needle is 20 dB over S9. For SSB phone the tone digit is omitted, so clear copy is reported as 59+20 dB.", - "source": "https://50ohm.de/N_rst.html", + "source": "https://50ohm.de/NEA_rst.html#BE206", "confidence": 8 }, "BE207": { - "revision": 3, + "revision": 4, "explanation": "On the digital display, the shown signal level is S5. For SSB phone the tone digit is omitted; clear copy gives R5, so the report is 55.", - "source": "https://50ohm.de/N_rst.html", + "source": "https://50ohm.de/NEA_rst.html#BE207", "confidence": 8 }, "BE208": { - "revision": 3, + "revision": 4, "explanation": "On the digital display, the shown signal level is S9. For SSB phone the tone digit is omitted; clear copy gives R5, so the report is 59.", - "source": "https://50ohm.de/N_rst.html", + "source": "https://50ohm.de/NEA_rst.html#BE208", "confidence": 8 }, "BE209": { - "revision": 3, + "revision": 4, "explanation": "On the digital display, the shown signal level is 20 dB over S9. For SSB phone the tone digit is omitted, so clear copy is reported as 59+20 dB.", - "source": "https://50ohm.de/N_rst.html", + "source": "https://50ohm.de/NEA_rst.html#BE209", "confidence": 8 }, "BE210": { - "revision": 2, + "revision": 3, "explanation": "SSTV sends pictures, so the practical way to report image quality is to include the report text in the transmitted image itself.", - "source": "https://50ohm.de/NE_sstv.html", + "source": "https://50ohm.de/NEA_sstv.html#BE210", "confidence": 8 }, "BE301": { - "revision": 1, + "revision": 2, "explanation": "Contests are structured operating exercises: competition pressure improves station setup, operator skill, and operating technique.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__2.html", + "source": "https://50ohm.de/NEA_contest.html#BE301", "confidence": 9 }, "BE302": { - "revision": 2, + "revision": 3, "explanation": "Contest scoring rewards many valid contacts in limited time, so exchanges are deliberately short and standardized.", - "source": "https://50ohm.de/N_contest.html", + "source": "https://50ohm.de/NEA_contest.html#BE302", "confidence": 8 }, "BE303": { - "revision": 2, + "revision": 3, "explanation": "A contest QSO counts only if both stations exchange the data required by that contest's rules.", - "source": "https://50ohm.de/N_contest.html", + "source": "https://50ohm.de/NEA_contest.html#BE303", "confidence": 8 }, "BE304": { - "revision": 2, + "revision": 3, "explanation": "In a Sprint contest, handing over the frequency after each QSO prevents one station from holding the run frequency continuously.", - "source": "https://50ohm.de/N_contest.html", + "source": "https://50ohm.de/NEA_contest.html#BE304", "confidence": 8 }, "BE305": { - "revision": 2, + "revision": 3, "explanation": "A pile-up is what happens when many stations call the same desirable station at once.", - "source": "https://50ohm.de/NE_pileup.html", + "source": "https://50ohm.de/NEA_pileup.html#BE305", "confidence": 8 }, "BE306": { - "revision": 2, + "revision": 3, "explanation": "'Only number 3' filters a pile-up by the numeral in the call sign, so only calls with 3 between prefix and suffix should call.", - "source": "https://50ohm.de/NE_pileup.html", + "source": "https://50ohm.de/NEA_pileup.html#BE306", "confidence": 8 }, "BE307": { - "revision": 2, + "revision": 3, "explanation": "List operation uses a strong control station to collect callers and call them in order, reducing chaos around a rare station.", - "source": "https://50ohm.de/NE_pileup.html", + "source": "https://50ohm.de/NEA_pileup.html#BE307", "confidence": 8 }, "BE308": { - "revision": 2, + "revision": 3, "explanation": "Split operation separates transmit and receive frequencies, letting a rare station listen where callers transmit while keeping its own transmit frequency clear.", - "source": "https://50ohm.de/N_split_betrieb.html", + "source": "https://50ohm.de/NEA_split_betrieb.html#BE308", "confidence": 8 }, "BE309": { - "revision": 2, + "revision": 3, "explanation": "'Split up 14270 to 14280' means the station transmits on its announced frequency but listens for callers across that higher range.", - "source": "https://50ohm.de/N_split_betrieb.html", + "source": "https://50ohm.de/NEA_split_betrieb.html#BE309", "confidence": 8 }, "BE310": { - "revision": 2, + "revision": 3, "explanation": "'5 up' means the wanted station listens 5 kHz above its transmit frequency, so callers must transmit there and listen on the station's frequency.", - "source": "https://50ohm.de/N_split_betrieb.html", + "source": "https://50ohm.de/NEA_split_betrieb.html#BE310", "confidence": 8 }, "BE311": { - "revision": 2, + "revision": 3, "explanation": "'Tuning 290 to 300 up' gives the listening window by shorthand: transmit between 14290 and 14300 kHz while listening to 14205 kHz.", - "source": "https://50ohm.de/N_split_betrieb.html", + "source": "https://50ohm.de/NEA_split_betrieb.html#BE311", "confidence": 8 }, "BE312": { - "revision": 2, + "revision": 3, "explanation": "A DX-pedition deliberately activates a rare country or island so other amateurs can work a location that is normally hard to hear.", - "source": "https://50ohm.de/N_dx.html", + "source": "https://50ohm.de/NEA_dx.html#BE312", "confidence": 8 }, "BE313": { - "revision": 2, + "revision": 3, "explanation": "ARDF is a direction-finding contest: operators use portable receivers to locate hidden low-power transmitters that transmit briefly.", - "source": "https://50ohm.de/NEA_ardf.html", + "source": "https://50ohm.de/NEA_ardf.html#BE313", "confidence": 8 }, "BE401": { - "revision": 2, + "revision": 3, "explanation": "A repeater is duplex: users transmit to its input, and the repeater retransmits what it hears on its output.", - "source": "https://50ohm.de/NE_relaisfunkstellen.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#BE401", "confidence": 8 }, "BE402": { - "revision": 1, + "revision": 2, "explanation": "German 2 m repeaters conventionally use a -600 kHz shift, so the input is 600 kHz below the output.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#BE402", "confidence": 7 }, "BE403": { - "revision": 1, + "revision": 2, "explanation": "German 70 cm repeaters conventionally use a -7.6 MHz shift, so the input is 7.6 MHz below the output.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2024/11/VHF_Handbook_V10_02.pdf", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#BE403", "confidence": 7 }, "BE404": { - "revision": 2, + "revision": 3, "explanation": "A short pause before each over leaves a gap for another station to break in without doubling.", - "source": "https://50ohm.de/NE_relaisfunkstellen.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#BE404", "confidence": 8 }, "BE405": { - "revision": 2, + "revision": 3, "explanation": "Clear handover tells everyone whose turn it is, which prevents two stations from transmitting at the same time.", - "source": "https://50ohm.de/NE_relaisfunkstellen.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#BE405", "confidence": 8 }, "BE406": { - "revision": 2, + "revision": 3, "explanation": "Repeaters are shared resources, and short overs leave access opportunities for mobile and portable users with changing signal conditions.", - "source": "https://50ohm.de/NE_relaisfunkstellen.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#BE406", "confidence": 8 }, "BE407": { - "revision": 2, + "revision": 3, "explanation": "Wide FM spills into adjacent repeater inputs and can overdrive a narrow repeater receiver, causing interference or distorted retransmission.", - "source": "https://50ohm.de/NE_relaisfunkstellen.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#BE407", "confidence": 8 }, "BE408": { - "revision": 2, + "revision": 3, "explanation": "Over a repeater, your S-meter reads the repeater's downlink, not the other user's uplink, so only readability describes the other user's signal.", - "source": "https://50ohm.de/NE_relaisfunkstellen.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#BE408", "confidence": 8 }, "BE409": { - "revision": 2, + "revision": 3, "explanation": "Beacons provide known reference signals; hearing or not hearing them indicates current propagation conditions.", - "source": "https://50ohm.de/NE_baken.html", + "source": "https://50ohm.de/NEA_baken.html#BE409", "confidence": 8 }, "BE410": { - "revision": 1, + "revision": 2, "explanation": "The International Beacon Project uses fixed beacon slots, so keeping those narrow ranges clear preserves their propagation-monitoring value.", - "source": "https://www.iaru-r1.org/wp-content/uploads/2021/06/hf_r1_bandplan.pdf", + "source": "https://50ohm.de/NEA_baken.html#BE410", "confidence": 7 }, "BE411": { - "revision": 2, + "revision": 3, "explanation": "Uplink is the direction from an earth station up to the satellite.", - "source": "https://50ohm.de/NEA_satelliten.html", + "source": "https://50ohm.de/NEA_satelliten.html#BE411", "confidence": 8 }, "BE412": { - "revision": 2, + "revision": 3, "explanation": "Downlink is the direction from the satellite down to earth stations.", - "source": "https://50ohm.de/NEA_satelliten.html", + "source": "https://50ohm.de/NEA_satelliten.html#BE412", "confidence": 8 }, "BE413": { - "revision": 2, + "revision": 3, "explanation": "Azimuth is the horizontal bearing angle used to point an antenna around the horizon.", - "source": "https://50ohm.de/NEA_satelliten.html", + "source": "https://50ohm.de/NEA_satelliten.html#BE413", "confidence": 8 }, "BE414": { - "revision": 2, + "revision": 3, "explanation": "Elevation is the vertical pointing angle above the horizon used to track a satellite.", - "source": "https://50ohm.de/NEA_satelliten.html", + "source": "https://50ohm.de/NEA_satelliten.html#BE414", "confidence": 8 }, "BE415": { - "revision": 2, + "revision": 3, "explanation": "OSCAR expands to Orbiting Satellite Carrying Amateur Radio, the usual name for amateur-radio satellites.", - "source": "https://50ohm.de/NEA_satelliten.html", + "source": "https://50ohm.de/NEA_satelliten.html#BE415", "confidence": 8 }, "BE416": { - "revision": 2, + "revision": 3, "explanation": "A satellite transponder receives signals on one band, translates them to another frequency range, and retransmits them back toward Earth.", - "source": "https://50ohm.de/NEA_satelliten.html", + "source": "https://50ohm.de/NEA_satelliten.html#BE416", "confidence": 8 }, "BF101": { - "revision": 2, + "revision": 3, "explanation": "Outside amateur radio, the internationally recognised distress signals are Mayday for voice and SOS for Morse or signalling.", - "source": "https://50ohm.de/N_notfunk.html", + "source": "https://50ohm.de/NEA_notfunk.html#BF101", "confidence": 8 }, "BF102": { - "revision": 1, + "revision": 2, "explanation": "AFuV §16 forbids using the international distress, urgency, and safety signals of maritime and aeronautical mobile services in amateur radio.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_notfunk.html#BF102", "confidence": 10 }, "BF103": { - "revision": 1, + "revision": 2, "explanation": "If normal communication is unavailable, amateur radio can support emergency assistance by relaying the request to someone who can contact police or rescue services.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__2.html", + "source": "https://50ohm.de/NEA_notfunk.html#BF103", "confidence": 9 }, "BF104": { - "revision": 2, + "revision": 3, "explanation": "The first task is accurate copying: listen and write down facts before transmitting so the emergency information is not lost or distorted.", - "source": "https://50ohm.de/N_notfunk.html", + "source": "https://50ohm.de/NEA_notfunk.html#BF104", "confidence": 8 }, "BF105": { - "revision": 2, + "revision": 3, "explanation": "If a rescue organisation has taken the traffic, extra amateur transmissions only risk interference, so the right action is to stay clear.", - "source": "https://50ohm.de/N_notfunk.html", + "source": "https://50ohm.de/NEA_notfunk.html#BF105", "confidence": 8 }, "BF106": { - "revision": 1, + "revision": 2, "explanation": "When no one else answers and you can help, acknowledging the distress traffic and alerting official emergency services is the useful relay path.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__2.html", + "source": "https://50ohm.de/NEA_notfunk.html#BF106", "confidence": 9 }, "BF107": { - "revision": 2, + "revision": 3, "explanation": "After relaying a distress message, remaining reachable lets you pass updates until professional help arrives or releases you.", - "source": "https://50ohm.de/N_notfunk.html", + "source": "https://50ohm.de/NEA_notfunk.html#BF107", "confidence": 8 }, "BF108": { - "revision": 2, + "revision": 3, "explanation": "Germany is UTC+2 during MESZ, so 23:00 UTC is 01:00 MESZ on the following local date.", - "source": "https://50ohm.de/N_notfunk.html", + "source": "https://50ohm.de/NEA_notfunk.html#BF108", "confidence": 8 }, "BF109": { - "revision": 1, + "revision": 2, "explanation": "IARU Region 1 designates these HF centres of activity for emergency communication, so they should be kept clear for that use.", - "source": "https://www.iaru-r1.org/about-us/committees-and-working-groups/emcomm/emergency-communications-frequencies/", + "source": "https://50ohm.de/NEA_notfunk.html#BF109", "confidence": 7 }, "BG101": { - "revision": 2, + "revision": 3, "explanation": "A logbook is the station diary: usually voluntary, but it can become mandatory when required for a particular station or case.", - "source": "https://50ohm.de/N_logbuch.html", + "source": "https://50ohm.de/NEA_logbuch.html#BG101", "confidence": 8 }, "BG102": { - "revision": 2, + "revision": 3, "explanation": "If log keeping is ordered, a computer log must remain readable for the required period just like a paper log.", - "source": "https://50ohm.de/N_logbuch.html", + "source": "https://50ohm.de/NEA_logbuch.html#BG102", "confidence": 8 }, "BG103": { - "revision": 2, + "revision": 3, "explanation": "Changing log software must not make ordered log data inaccessible, because the records may need later inspection.", - "source": "https://50ohm.de/N_logbuch.html", + "source": "https://50ohm.de/NEA_logbuch.html#BG103", "confidence": 8 }, "BG104": { - "revision": 2, + "revision": 3, "explanation": "A QSL card confirms that a QSO took place and can serve as evidence for awards that require worked stations or countries.", - "source": "https://50ohm.de/NEA_qsl_karten.html", + "source": "https://50ohm.de/NEA_qsl_karten.html#BG104", "confidence": 8 }, "BG105": { - "revision": 2, + "revision": 3, "explanation": "A useful QSL must identify both stations and the contact: call signs, UTC date/time, band, mode, and signal report are the minimum facts.", - "source": "https://50ohm.de/NEA_qsl_karten.html", + "source": "https://50ohm.de/NEA_qsl_karten.html#BG105", "confidence": 8 }, "BG106": { - "revision": 2, + "revision": 3, "explanation": "UTC avoids local time-zone and daylight-saving ambiguity, making it easier for foreign stations to match the card to their log.", - "source": "https://50ohm.de/NEA_qsl_karten.html", + "source": "https://50ohm.de/NEA_qsl_karten.html#BG106", "confidence": 8 }, "BG107": { - "revision": 2, + "revision": 3, "explanation": "MEZ is UTC+1, so 15:30 local standard time is 14:30 UTC.", - "source": "https://50ohm.de/NEA_qsl_karten.html", + "source": "https://50ohm.de/NEA_qsl_karten.html#BG107", "confidence": 8 }, "BG108": { - "revision": 2, + "revision": 3, "explanation": "MESZ is UTC+2, so 13:30 local daylight-saving time is 11:30 UTC.", - "source": "https://50ohm.de/NEA_qsl_karten.html", + "source": "https://50ohm.de/NEA_qsl_karten.html#BG108", "confidence": 8 }, "BG109": { - "revision": 2, + "revision": 3, "explanation": "'QSL via K8PYD' means K8PYD manages cards for HZ1HZ, so sending through that manager is the route to confirmation.", - "source": "https://50ohm.de/NEA_qsl_karten.html", + "source": "https://50ohm.de/NEA_qsl_karten.html#BG109", "confidence": 8 }, "BG110": { - "revision": 2, + "revision": 3, "explanation": "Direct QSL mailing needs a current address, which is why operators use callbooks or online call-sign information.", - "source": "https://50ohm.de/NEA_qsl_karten.html", + "source": "https://50ohm.de/NEA_qsl_karten.html#BG110", "confidence": 8 }, "BG111": { - "revision": 2, + "revision": 3, "explanation": "Electronic QSL systems and log uploads confirm the same QSO facts without exchanging a physical card.", - "source": "https://50ohm.de/NEA_qsl_karten.html", + "source": "https://50ohm.de/NEA_qsl_karten.html#BG111", "confidence": 8 }, "EA101": { - "revision": 2, - "explanation": "Capacitance is the charge stored per volt, $C = Q/U$, so its named SI-derived unit is the farad (F) — one coulomb per volt. Ohm ($\\Omega$) is resistance, henry (H) is inductance, and ampere-hours measure charge, so none of those fit capacitance.", - "source": "https://50ohm.de/EA_kondensator_1.html", + "revision": 3, + "explanation": "Capacitance is the charge stored per volt, $C = Q/U$, so its named SI-derived unit is the farad (F) — one coulomb per volt. Ohm ($\\Omega$) is resistance, henry (H) is inductance, and ampere-hours measure charge, so none of those fit capacitance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kondensator_1.html#EA101", "confidence": 8 }, "EA102": { - "revision": 2, - "explanation": "Inductance describes how much magnetic flux linkage a conductor or coil produces per ampere: $L = \\Psi/I$. A larger inductance stores more magnetic-field energy for the same current, and its named SI-derived unit is the henry (H).", - "source": "https://50ohm.de/EA_spule_1.html", + "revision": 3, + "explanation": "Inductance describes how much magnetic flux linkage a conductor or coil produces per ampere: $L = \\Psi/I$. A larger inductance stores more magnetic-field energy for the same current, and its named SI-derived unit is the henry (H). Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spule_1.html#EA102", "confidence": 8 }, "EA103": { - "revision": 2, + "revision": 3, "explanation": "Electric field strength is voltage per distance: $E = U/d$. That is why the unit is volts per metre (V/m), not just volts; it tells how steeply electric potential changes through space.", - "source": "https://50ohm.de/EA_e_feld.html", + "source": "https://50ohm.de/NEA_e_feld.html#EA103", "confidence": 8 }, "EA104": { - "revision": 2, + "revision": 3, "explanation": "Magnetic field strength $H$ is given in amperes per metre (A/m). The straight-wire case shows why: $H = I/(2\\pi r)$ is a current (amperes) spread over a circumference (metres). Keep $H$ (field strength, A/m) distinct from flux density $B$ (tesla); option D, H/m, is the unit of permeability instead.", - "source": "https://50ohm.de/EA_h_feld.html", + "source": "https://50ohm.de/NEA_h_feld.html#EA104", "confidence": 8 }, "EA105": { - "revision": 3, + "revision": 4, "explanation": "Bandwidth is not a separate physical kind of quantity; it is the width of a frequency range. Since both endpoints are frequencies, their difference is also measured in hertz: $B = f_2 - f_1$.", - "source": "https://50ohm.de/E_slide_e_modulation.html", + "source": "https://50ohm.de/NEA_bandbreite_2.html#EA105", "confidence": 8 }, "EA106": { - "revision": 2, + "revision": 3, "explanation": "A data-transmission rate counts how many bits cross per second, so the unit is bit/s. The trap is baud (Bd), which counts symbols per second and equals bit/s only when each symbol carries exactly one bit; hertz is for frequency and decibel for ratios.", - "source": "https://50ohm.de/NEA_datenuebertragungsdrate.html", + "source": "https://50ohm.de/NEA_datenuebertragungsdrate.html#EA106", "confidence": 8 }, "EA107": { - "revision": 2, - "explanation": "A power level in decibels is $L = 10\\log_{10}(P_2/P_1)$. Doubling power gives $10\\log_{10}(2) = 10 \\cdot 0.301 \\approx 3$ dB. Worth memorising: $\\times 2$ power $= +3$ dB and $\\times 10$ power $= +10$ dB. (Doubling a voltage is $+6$ dB, because voltage ratios use $20\\log_{10}$.)", - "source": "https://50ohm.de/E_dezibel_1.html", + "revision": 4, + "explanation": "A power level in decibels is $L = 10\\log_{10}(P_2/P_1)$. Doubling power gives $10\\log_{10}(2) = 10 \\cdot 0.301 \\approx 3$ dB. Worth memorising: $\\times 2$ power $= +3$ dB and $\\times 10$ power $= +10$ dB. (Doubling a voltage is $+6$ dB, because voltage ratios use $20\\log_{10}$.) Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_dezibel_1.html#EA107", "confidence": 8 }, "EA108": { - "revision": 2, - "explanation": "Micro ($\\mu$) means $10^{-6}$. Expressing $0.00042$ A in microamperes shifts the decimal six places: $0.00042$ A $= 420 \\cdot 10^{-6}$ A $= 420\\ \\mu$A. Option D, $42 \\cdot 10^{-6}$ A, is ten times too small.", - "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "revision": 3, + "explanation": "Micro ($\\mu$) means $10^{-6}$. Expressing $0.00042$ A in microamperes shifts the decimal six places: $0.00042$ A $= 420 \\cdot 10^{-6}$ A $= 420\\ \\mu$A. Option D, $42 \\cdot 10^{-6}$ A, is ten times too small. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html#EA108", "confidence": 8 }, "EA109": { - "revision": 2, - "explanation": "Milli means $10^{-3}$. Move from amperes to milliamperes by multiplying by 1000: $0.042 A = 42 mA = 42 \\cdot 10^{-3} A$.", - "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "revision": 3, + "explanation": "Milli means $10^{-3}$. Move from amperes to milliamperes by multiplying by 1000: $0.042 A = 42 mA = 42 \\cdot 10^{-3} A$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html#EA109", "confidence": 8 }, "EA110": { - "revision": 2, - "explanation": "Scientific notation keeps one non-zero digit before the decimal point. Moving the decimal in $4,200,000$ six places gives $4.2 \\cdot 10^6 Hz$, i.e. 4.2 MHz.", - "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "revision": 3, + "explanation": "Scientific notation keeps one non-zero digit before the decimal point. Moving the decimal in $4,200,000$ six places gives $4.2 \\cdot 10^6 Hz$, i.e. 4.2 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html#EA110", "confidence": 8 }, "EA111": { - "revision": 2, - "explanation": "A millivolt is $10^{-3} V$ and a microvolt is $10^{-6} V$. So $0.01 mV = 0.01 \\cdot 10^{-3} V = 10 \\cdot 10^{-6} V = 10 µV$.", - "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "revision": 3, + "explanation": "A millivolt is $10^{-3} V$ and a microvolt is $10^{-6} V$. So $0.01 mV = 0.01 \\cdot 10^{-3} V = 10 \\cdot 10^{-6} V = 10 µV$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html#EA111", "confidence": 8 }, "EA112": { - "revision": 2, - "explanation": "Mega means $10^6$. Therefore $0.002 MOhm = 0.002 \\cdot 10^6 Ohm = 2000 Ohm = 2 kOhm$.", - "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "revision": 3, + "explanation": "Mega means $10^6$. Therefore $0.002 MOhm = 0.002 \\cdot 10^6 Ohm = 2000 Ohm = 2 kOhm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html#EA112", "confidence": 8 }, "EA113": { - "revision": 2, - "explanation": "A microwatt is $10^{-6} W$. To convert watts to microwatts, divide by $10^{-6}$: $2 \\cdot 10^{-7} W / 10^{-6} = 0.2 µW$.", - "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "revision": 3, + "explanation": "A microwatt is $10^{-6} W$. To convert watts to microwatts, divide by $10^{-6}$: $2 \\cdot 10^{-7} W / 10^{-6} = 0.2 µW$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html#EA113", "confidence": 8 }, "EA114": { - "revision": 2, - "explanation": "$5 \\cdot 10^{-1} W$ is $0.5 W$. Since $1 W = 1000 mW$, $0.5 W = 500 mW$.", - "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "revision": 3, + "explanation": "$5 \\cdot 10^{-1} W$ is $0.5 W$. Since $1 W = 1000 mW$, $0.5 W = 500 mW$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html#EA114", "confidence": 8 }, "EA115": { - "revision": 2, - "explanation": "Micro is $10^{-6}$ and nano is $10^{-9}$, so one microfarad is 1000 nanofarads. Thus $0.22 µF = 0.22 \\cdot 1000 nF = 220 nF$.", - "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "revision": 4, + "explanation": "Micro is $10^{-6}$ and nano is $10^{-9}$, so one microfarad is 1000 nanofarads. Thus $0.22 µF = 0.22 \\cdot 1000 nF = 220 nF$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html#EA115", "confidence": 8 }, "EA116": { - "revision": 2, - "explanation": "Kilo is $10^3$ and mega is $10^6$, so converting kHz to MHz divides by 1000. $3750 kHz = 3.750 MHz$.", - "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "revision": 4, + "explanation": "Kilo is $10^3$ and mega is $10^6$, so converting kHz to MHz divides by 1000. $3750 kHz = 3.750 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html#EA116", "confidence": 8 }, "EA201": { - "revision": 2, + "revision": 3, "explanation": "Binary needs only two symbols, 0 and 1, which map directly onto two robust electrical states — a switching element such as a transistor is simply off or on (low or high voltage). Multi-level analog states (option C) are far harder to keep reliable across temperature and noise, so digital logic builds everything from clean two-state switching.", - "source": "https://50ohm.de/EA_binaer.html", + "source": "https://50ohm.de/NEA_binaer.html#EA201", "confidence": 8 }, "EA202": { - "revision": 2, + "revision": 3, "explanation": "A bit has two possible states. With independent bits, the possibilities multiply, so $n$ bits can represent $2^n$ combinations. For 3 bits: $2^3 = 8$.", - "source": "https://50ohm.de/EA_binaer.html", + "source": "https://50ohm.de/NEA_binaer.html#EA202", "confidence": 8 }, "EA203": { - "revision": 2, + "revision": 3, "explanation": "Every additional bit doubles the number of representable values. Four bits therefore give $2^4 = 16$ combinations, from binary 0000 to 1111.", - "source": "https://50ohm.de/EA_binaer.html", + "source": "https://50ohm.de/NEA_binaer.html#EA203", "confidence": 8 }, "EA204": { - "revision": 2, + "revision": 3, "explanation": "For binary numbers, count values with $2^n$. A five-bit word has $2^5 = 32$ possible patterns, so it can represent 32 values.", - "source": "https://50ohm.de/EA_binaer.html", + "source": "https://50ohm.de/NEA_binaer.html#EA204", "confidence": 8 }, "EA205": { - "revision": 2, + "revision": 3, "explanation": "Read binary by place values: 128, 64, 32, 16, 8, 4, 2, 1. In $01001110_2$, the set bits are $64 + 8 + 4 + 2 = 78$; the leading zero just pads the byte.", - "source": "https://50ohm.de/EA_binaer.html", + "source": "https://50ohm.de/NEA_binaer.html#EA205", "confidence": 8 }, "EA206": { - "revision": 2, + "revision": 3, "explanation": "Use binary place values. $10001110_2$ has bits set at 128, 8, 4 and 2, so the decimal value is $128 + 8 + 4 + 2 = 142$.", - "source": "https://50ohm.de/EA_binaer.html", + "source": "https://50ohm.de/NEA_binaer.html#EA206", "confidence": 8 }, "EA207": { - "revision": 2, + "revision": 3, "explanation": "$10011100_2$ uses the 128, 16, 8 and 4 places. Adding those weights gives $128 + 16 + 8 + 4 = 156$.", - "source": "https://50ohm.de/EA_binaer.html", + "source": "https://50ohm.de/NEA_binaer.html#EA207", "confidence": 8 }, "EA208": { - "revision": 2, + "revision": 3, "explanation": "$11111000_2$ has the five upper places set and the three lower places clear. $128 + 64 + 32 + 16 + 8 = 248$.", - "source": "https://50ohm.de/EA_binaer.html", + "source": "https://50ohm.de/NEA_binaer.html#EA208", "confidence": 8 }, "EB101": { - "revision": 3, + "revision": 4, "explanation": "Well inside a large parallel-plate capacitor the field lines run straight, parallel, and evenly spaced — a homogeneous (uniform) electric field, the same strength and direction everywhere. (Fringing curves the field only at the plate edges.) The field between charged plates is electric, not magnetic.", - "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "source": "https://50ohm.de/NEA_e_feld.html#EB101", "confidence": 8 }, "EB102": { - "revision": 3, - "explanation": "In the uniform field of a plate capacitor, field strength is voltage over gap: $E = U/d$. Convert the spacing, $0.6\\ \\text{cm} = 0.006$ m, then $E = 9\\ \\text{V} / 0.006\\ \\text{m} = 1500$ V/m. The unit V/m comes straight out of the formula.", - "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "revision": 5, + "explanation": "In the uniform field of a plate capacitor, field strength is voltage over gap: $E = U/d$. Convert the spacing, $0.6\\ \\text{cm} = 0.006$ m, then $E = 9\\ \\text{V} / 0.006\\ \\text{m} = 1500$ V/m. The unit V/m comes straight out of the formula. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_e_feld.html#EB102", "confidence": 8 }, "EB103": { - "revision": 3, - "explanation": "Use $E = U/d$ with the dielectric thickness as the gap: $0.15\\ \\text{mm} = 1.5 \\cdot 10^{-4}$ m. Then $E = 300\\ \\text{V} / (1.5 \\cdot 10^{-4}\\ \\text{m}) = 2.0 \\cdot 10^6$ V/m $= 2000$ kV/m. Thin dielectrics produce enormous field strengths even at modest voltages.", - "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "revision": 5, + "explanation": "Use $E = U/d$ with the dielectric thickness as the gap: $0.15\\ \\text{mm} = 1.5 \\cdot 10^{-4}$ m. Then $E = 300\\ \\text{V} / (1.5 \\cdot 10^{-4}\\ \\text{m}) = 2.0 \\cdot 10^6$ V/m $= 2000$ kV/m. Thin dielectrics produce enormous field strengths even at modest voltages. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_e_feld.html#EB103", "confidence": 8 }, "EB104": { - "revision": 3, - "explanation": "Dielectric (breakdown) strength is a maximum field strength, so rearrange $E = U/d$ to $U_{\\max} = E \\cdot d$. Keep units consistent: $0.15\\ \\text{mm} = 0.015$ cm, so $U_{\\max} = 400\\ \\text{kV/cm} \\cdot 0.015\\ \\text{cm} = 6$ kV. Above that, the PTFE film punches through.", - "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "revision": 5, + "explanation": "Dielectric (breakdown) strength is a maximum field strength, so rearrange $E = U/d$ to $U_{\\max} = E \\cdot d$. Keep units consistent: $0.15\\ \\text{mm} = 0.015$ cm, so $U_{\\max} = 400\\ \\text{kV/cm} \\cdot 0.015\\ \\text{cm} = 6$ kV. Above that, the PTFE film punches through. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_e_feld.html#EB104", "confidence": 8 }, "EB105": { - "revision": 3, + "revision": 4, "explanation": "At a vertical antenna, the electric field (E-field) is drawn along the voltage path between the conductor and the surrounding ground/reference. The closed concentric loops around the conductor are the magnetic field (H-field), caused by RF current, so the marked vertical/open field lines are the electric field.", - "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "source": "https://50ohm.de/NEA_e_feld.html#EB105", "confidence": 8 }, "EB201": { - "revision": 2, + "revision": 3, "explanation": "A current in a straight conductor produces a magnetic field whose lines close on themselves, encircling the wire as concentric circles (right-hand rule). They are magnetic, not electric, and circular rather than radial/star-shaped.", - "source": "https://50ohm.de/EA_h_feld.html", + "source": "https://50ohm.de/NEA_h_feld.html#EB201", "confidence": 8 }, "EB202": { - "revision": 3, + "revision": 4, "explanation": "Inside a long solenoid (Zylinderspule) carrying DC, the turns' fields add to give nearly straight, parallel, evenly spaced lines along the axis — an approximately homogeneous (uniform) magnetic field. It is magnetic (current-driven) and uniform, like the electric analogue inside a plate capacitor.", - "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "source": "https://50ohm.de/NEA_h_feld.html#EB202", "confidence": 8 }, "EB203": { - "revision": 2, - "explanation": "For a toroid the magnetic path length is the mean circumference, $l_m = \\pi d$, and Ampere's law gives $H = N I / l_m = N I / (\\pi d)$. Here $H = (6 \\cdot 2.5) / (\\pi \\cdot 0.026\\ \\text{m}) = 15 / 0.0817 \\approx 183.6$ A/m. Watch the units — using the diameter in cm would shift the answer by $100\\times$.", - "source": "https://50ohm.de/NEA_slide_nea_em_feld.html?print-pdf=&showNotes=true", + "revision": 4, + "explanation": "For a toroid the magnetic path length is the mean circumference, $l_m = \\pi d$, and Ampere's law gives $H = N I / l_m = N I / (\\pi d)$. Here $H = (6 \\cdot 2.5) / (\\pi \\cdot 0.026\\ \\text{m}) = 15 / 0.0817 \\approx 183.6$ A/m. Watch the units — using the diameter in cm would shift the answer by $100\\times$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_h_feld.html#EB203", "confidence": 8 }, "EB204": { - "revision": 2, + "revision": 3, "explanation": "Of these, only iron (Eisen) is ferromagnetic at room temperature — strongly magnetisable, ideal for inductor and transformer cores. Copper and aluminium are non-magnetic, and chromium is not ferromagnetic at room temperature, so they cannot serve as a core.", - "source": "https://50ohm.de/E_spule_1.html", + "source": "https://50ohm.de/NEA_spule_1.html#EB204", "confidence": 8 }, "EB205": { - "revision": 5, + "revision": 6, "explanation": "At RF, a conductive copper or aluminium core develops eddy currents. By Lenz's law these currents create an opposing magnetic field, so the changing RF flux is screened from the core interior and the effective magnetic cross-section becomes smaller. Less linked flux for the same current means lower inductance.", - "source": "https://50ohm.de/NEA_spule_1.html", + "source": "https://50ohm.de/NEA_spule_1.html#EB205", "confidence": 8 }, "EB206": { - "revision": 3, + "revision": 4, "explanation": "A current-carrying antenna conductor produces a magnetic field (H-field) in closed loops around the conductor, following the right-hand rule. The electric field (E-field) is not the closed loop; it is associated with voltage between conductor and reference/ground.", - "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "source": "https://50ohm.de/NEA_h_feld.html#EB206", "confidence": 8 }, "EB301": { - "revision": 3, + "revision": 4, "explanation": "Radiation needs changing fields. A time-varying current in a conductor (e.g. the RF current in an antenna) produces a time-varying magnetic field, which in turn induces an electric field — the coupled pair is the electromagnetic field. A steady DC current gives only a static magnetic field that does not radiate.", - "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "source": "https://50ohm.de/NEA_em_feld.html#EB301", "confidence": 8 }, "EB302": { - "revision": 3, + "revision": 4, "explanation": "An electromagnetic wave is self-sustaining: a changing electric field induces a magnetic field and the changing magnetic field induces an electric field, so the two regenerate each other as the wave travels (Maxwell's equations). Neither field propagates alone in the far field — they are inseparable partners.", - "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "source": "https://50ohm.de/NEA_em_feld.html#EB302", "confidence": 8 }, "EB303": { - "revision": 2, + "revision": 3, "explanation": "In the far field of free-space propagation the wave is transverse (TEM): the $E$ and $H$ vectors lie at right angles to each other and to the direction of travel. So the angle between the electric and magnetic field components is $90^\\circ$.", - "source": "https://50ohm.de/NEA_fernfeld.html", + "source": "https://50ohm.de/NEA_em_feld.html#EB303", "confidence": 8 }, "EB304": { - "revision": 2, + "revision": 3, "explanation": "An undisturbed far field is a TEM wave: the $E$-field, the $H$-field, and the propagation direction form a mutually perpendicular (right-angled) triad, with $E$ and $H$ in phase. The propagation direction is fixed by $E \\times H$ (the Poynting vector), so it is not free as the wrong options claim.", - "source": "https://50ohm.de/NEA_fernfeld.html", + "source": "https://50ohm.de/NEA_em_feld.html#EB304", "confidence": 8 }, "EB305": { - "revision": 3, - "explanation": "By convention the polarisation of a wave is the direction of its electric-field vector ($E$). A vertical $E$-field is vertical polarisation, horizontal is horizontal. It is defined by the E-field, not the magnetic field, the travel direction, or the near field.", - "source": "https://50ohm.de/NEA_polarisation_2.html", + "revision": 4, + "explanation": "By convention the polarisation of a wave is the direction of its electric-field vector ($E$). A vertical $E$-field is vertical polarisation, horizontal is horizontal. It is defined by the E-field, not the magnetic field, the travel direction, or the near field. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_polarisation_2.html#EB305", "confidence": 8 }, "EB306": { - "revision": 3, + "revision": 4, "explanation": "Polarization is defined by the direction of the electric-field vector, not by the magnetic field or travel direction. In this drawing the E-field lies horizontally, so the electromagnetic wave is horizontally polarized.", - "source": "https://50ohm.de/NEA_polarisation_2.html", + "source": "https://50ohm.de/NEA_polarisation_2.html#EB306", "confidence": 8 }, "EB307": { - "revision": 3, + "revision": 4, "explanation": "For radio waves, polarization follows the electric field (E-field). The E-field in the figure is vertical, so the wave is vertically polarized; the magnetic field is at right angles to it and does not name the polarization.", - "source": "https://50ohm.de/NEA_polarisation_2.html", + "source": "https://50ohm.de/NEA_polarisation_2.html#EB307", "confidence": 8 }, "EB308": { - "revision": 3, + "revision": 4, "explanation": "Circular polarization means the electric-field vector rotates as the wave propagates instead of staying vertical or horizontal. A receiving antenna then sees a rotating field rather than one fixed linear direction.", - "source": "https://50ohm.de/NEA_polarisation_2.html", + "source": "https://50ohm.de/NEA_polarisation_2.html#EB308", "confidence": 8 }, "EB309": { - "revision": 3, + "revision": 4, "explanation": "A linear antenna launches an electric field in the same orientation as the radiating element in its main direction. Since the shown elements are horizontal, the emitted wave is horizontally polarized.", - "source": "https://50ohm.de/NEA_polarisation_2.html", + "source": "https://50ohm.de/NEA_polarisation_2.html#EB309", "confidence": 8 }, "EB310": { - "revision": 3, + "revision": 4, "explanation": "The polarization of a linearly polarized wave is the orientation of its electric field. In the shown main radiation direction that field is vertical, so the transmitted signal is vertically polarized.", - "source": "https://50ohm.de/NEA_polarisation_2.html", + "source": "https://50ohm.de/NEA_polarisation_2.html#EB310", "confidence": 8 }, "EB311": { - "revision": 2, - "explanation": "Wavelength and frequency are linked by $\\lambda = c/f$. Using the handy form $\\lambda_{\\text{m}} \\approx 300 / f_{\\text{MHz}}$: $300 / 1.84 \\approx 163$ m. (At $1.84$ MHz this is the $160$ m band, and $163$ m fits.)", - "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "revision": 3, + "explanation": "Wavelength and frequency are linked by $\\lambda = c/f$. Using the handy form $\\lambda_{\\text{m}} \\approx 300 / f_{\\text{MHz}}$: $300 / 1.84 \\approx 163$ m. (At $1.84$ MHz this is the $160$ m band, and $163$ m fits.) Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wellenlaenge_2.html#EB311", "confidence": 8 }, "EB312": { - "revision": 2, - "explanation": "Use $\\lambda = c/f$. For radio exam mental math, with $c \\approx 300$ million m/s and frequency in MHz, $\\lambda_m \\approx 300/f_{MHz}$. At 21 MHz, $300/21 \\approx 14.29$ m.", - "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "revision": 3, + "explanation": "Use $\\lambda = c/f$. For radio exam mental math, with $c \\approx 300$ million m/s and frequency in MHz, $\\lambda_m \\approx 300/f_{MHz}$. At 21 MHz, $300/21 \\approx 14.29$ m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wellenlaenge_2.html#EB312", "confidence": 8 }, "EB313": { - "revision": 2, - "explanation": "Wavelength and frequency are inversely related: $\\lambda = c/f$. With frequency in MHz, use $\\lambda_m \\approx 300/f_{MHz}$; for 28.5 MHz this gives $300/28.5 \\approx 10.5$ m.", - "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "revision": 3, + "explanation": "Wavelength and frequency are inversely related: $\\lambda = c/f$. With frequency in MHz, use $\\lambda_m \\approx 300/f_{MHz}$; for 28.5 MHz this gives $300/28.5 \\approx 10.5$ m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wellenlaenge_2.html#EB313", "confidence": 8 }, "EB314": { - "revision": 2, - "explanation": "Rearrange $\\lambda = c/f$ to $f \\approx 300 / \\lambda_{\\text{m}}$ (MHz with metres): $f = 300 / 80.0 = 3.75$ MHz. That places $80$ m wavelength in the $80$ m band, as expected.", - "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "revision": 3, + "explanation": "Rearrange $\\lambda = c/f$ to $f \\approx 300 / \\lambda_{\\text{m}}$ (MHz with metres): $f = 300 / 80.0 = 3.75$ MHz. That places $80$ m wavelength in the $80$ m band, as expected. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wellenlaenge_2.html#EB314", "confidence": 8 }, "EB315": { - "revision": 2, - "explanation": "Convert first: $30\\ \\text{mm} = 0.03$ m. Then $f = c/\\lambda = 3 \\cdot 10^8 / 0.03 = 1 \\cdot 10^{10}$ Hz $= 10$ GHz. Centimetre wavelengths mean microwave (GHz) frequencies.", - "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "revision": 3, + "explanation": "Convert first: $30\\ \\text{mm} = 0.03$ m. Then $f = c/\\lambda = 3 \\cdot 10^8 / 0.03 = 1 \\cdot 10^{10}$ Hz $= 10$ GHz. Centimetre wavelengths mean microwave (GHz) frequencies. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wellenlaenge_2.html#EB315", "confidence": 8 }, "EB316": { - "revision": 2, - "explanation": "With $\\lambda = 10\\ \\text{cm} = 0.1$ m, $f = c/\\lambda = 3 \\cdot 10^8 / 0.1 = 3 \\cdot 10^9$ Hz $= 3$ GHz. ($10$ cm is the $13$ cm-ish microwave region, so GHz is right.)", - "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "revision": 3, + "explanation": "With $\\lambda = 10\\ \\text{cm} = 0.1$ m, $f = c/\\lambda = 3 \\cdot 10^8 / 0.1 = 3 \\cdot 10^9$ Hz $= 3$ GHz. ($10$ cm is the $13$ cm-ish microwave region, so GHz is right.) Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wellenlaenge_2.html#EB316", "confidence": 8 }, "EB401": { - "revision": 3, - "explanation": "For a sine wave, RMS is the heating-equivalent DC value and the peak is larger by $\\sqrt{2}$. Mains 230 V is RMS, so $U_{peak} = 230 V \\cdot \\sqrt{2} \\approx 325 V$.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "revision": 5, + "explanation": "For a sine wave, RMS is the heating-equivalent DC value and the peak is larger by $\\sqrt{2}$. Mains 230 V is RMS, so $U_{peak} = 230 V \\cdot \\sqrt{2} \\approx 325 V$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spitze_effektiv_wert.html#EB401", "confidence": 8 }, "EB402": { - "revision": 3, - "explanation": "Peak-to-peak voltage is the full swing from negative peak to positive peak: $U_{pp} = 2 U_{peak}$. From 230 V RMS, $U_{peak} = 230\\sqrt{2} \\approx 325 V$, so $U_{pp} \\approx 650 V$.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "revision": 5, + "explanation": "Peak-to-peak voltage is the full swing from negative peak to positive peak: $U_{pp} = 2 U_{peak}$. From 230 V RMS, $U_{peak} = 230\\sqrt{2} \\approx 325 V$, so $U_{pp} \\approx 650 V$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spitze_effektiv_wert.html#EB402", "confidence": 8 }, "EB403": { - "revision": 3, - "explanation": "For sine waves, $U_{peak} = U_{RMS}\\sqrt{2}$ and $U_{pp} = 2U_{peak}$. With 12 V RMS, the peak is about 17 V and peak-to-peak is about 34 V.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "revision": 5, + "explanation": "For sine waves, $U_{peak} = U_{RMS}\\sqrt{2}$ and $U_{pp} = 2U_{peak}$. With 12 V RMS, the peak is about 17 V and peak-to-peak is about 34 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spitze_effektiv_wert.html#EB403", "confidence": 8 }, "EB404": { - "revision": 3, - "explanation": "For sine waves, RMS is peak divided by $\\sqrt{2}$ because RMS represents equal heating power. $12 V / 1.414 \\approx 8.5 V$.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "revision": 5, + "explanation": "For sine waves, RMS is peak divided by $\\sqrt{2}$ because RMS represents equal heating power. $12 V / 1.414 \\approx 8.5 V$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spitze_effektiv_wert.html#EB404", "confidence": 8 }, "EB405": { - "revision": 3, - "explanation": "The DC voltage that heats a resistor the same as a sine is the sine's RMS (effective) value, and either polarity heats equally. For a $1$ V peak sine, $U_{\\text{RMS}} = 1/\\sqrt{2} \\approx 0.7$ V, so $+0.7$ V and $-0.7$ V both dissipate the same power as the AC waveform.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "revision": 5, + "explanation": "The DC voltage that heats a resistor the same as a sine is the sine's RMS (effective) value, and either polarity heats equally. For a $1$ V peak sine, $U_{\\text{RMS}} = 1/\\sqrt{2} \\approx 0.7$ V, so $+0.7$ V and $-0.7$ V both dissipate the same power as the AC waveform. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spitze_effektiv_wert.html#EB405", "confidence": 8 }, "EB406": { - "revision": 3, - "explanation": "On an oscilloscope, peak-to-peak voltage is the vertical distance from trough to crest. Count vertical divisions and multiply by volts/div; the shown trace reads 12 V peak-to-peak.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "revision": 5, + "explanation": "On an oscilloscope, peak-to-peak voltage is the vertical distance from trough to crest. Count vertical divisions and multiply by volts/div; the shown trace reads 12 V peak-to-peak. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spitze_effektiv_wert.html#EB406", "confidence": 8 }, "EB407": { - "revision": 3, - "explanation": "Peak-to-peak is the complete positive-to-negative swing. If the diagram gives a 20 V peak from zero to one crest, the full swing is $2 \\cdot 20 V = 40 V$.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "revision": 4, + "explanation": "Peak-to-peak is the complete positive-to-negative swing. If the diagram gives a 20 V peak from zero to one crest, the full swing is $2 \\cdot 20 V = 40 V$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spitze_effektiv_wert.html#EB407", "confidence": 8 }, "EB408": { - "revision": 3, - "explanation": "Frequency is cycles per second, so it is the reciprocal of period: $f = 1/T$. With $T = 50 µs = 50 \\cdot 10^{-6} s$, $f = 1/T = 20,000 Hz = 20 kHz$.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "revision": 5, + "explanation": "Frequency is cycles per second, so it is the reciprocal of period: $f = 1/T$. With $T = 50 µs = 50 \\cdot 10^{-6} s$, $f = 1/T = 20,000 Hz = 20 kHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_oszilloskop_1.html#EB408", "confidence": 8 }, "EB409": { - "revision": 3, - "explanation": "First read one full cycle on the oscilloscope grid to get the period $T$, then use $f = 1/T$. The trace period is about $12 µs$, so $f \\approx 1/(12 \\cdot 10^{-6}) = 83.3 kHz$.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "revision": 5, + "explanation": "First read one full cycle on the oscilloscope grid to get the period $T$, then use $f = 1/T$. The trace period is about $12 µs$, so $f \\approx 1/(12 \\cdot 10^{-6}) = 83.3 kHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_oszilloskop_1.html#EB409", "confidence": 8 }, "EB410": { - "revision": 3, - "explanation": "Oscilloscope timebase reading is divisions times time/div. Four divisions at 5 ms/div gives $T = 20 ms = 0.020 s$, so $f = 1/T = 50 Hz$.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "revision": 5, + "explanation": "Oscilloscope timebase reading is divisions times time/div. Four divisions at 5 ms/div gives $T = 20 ms = 0.020 s$, so $f = 1/T = 50 Hz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_oszilloskop_1.html#EB410", "confidence": 8 }, "EB411": { - "revision": 3, - "explanation": "Read the period from the grid: $4 \\cdot 0.03 µs = 0.12 µs$. Then $f = 1/T = 1/(0.12 \\cdot 10^{-6} s) \\approx 8.33 MHz$.", - "source": "https://50ohm.de/NE_oszilloskop_1.html", + "revision": 5, + "explanation": "Read the period from the grid: $4 \\cdot 0.03 µs = 0.12 µs$. Then $f = 1/T = 1/(0.12 \\cdot 10^{-6} s) \\approx 8.33 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_oszilloskop_1.html#EB411", "confidence": 8 }, "EB501": { - "revision": 2, + "revision": 3, "explanation": "PEP (peak envelope power, Spitzenleistung) is the average power over one RF cycle taken at the highest crest of the modulation envelope, into a real (resistive) load, under normal operation. The key is 'one RF cycle at the envelope peak' — averaging over a long interval instead would give mean power, and the dipole-gain option describes ERP.", - "source": "https://life.itu.int/radioclub/rr/art1.pdf", + "source": "https://50ohm.de/NEA_senderausgangsleistung.html#EB501", "confidence": 9 }, "EB502": { - "revision": 2, + "revision": 3, "explanation": "Mean power (mittlere Leistung) is averaged over a time long compared with the period of the lowest modulation frequency — i.e. the long-term average delivered to the feed line. Contrast PEP, which is measured over a single RF cycle at the envelope peak; the gain-product option describes ERP.", - "source": "https://life.itu.int/radioclub/rr/art1.pdf", + "source": "https://50ohm.de/NEA_senderausgangsleistung.html#EB502", "confidence": 9 }, "EB503": { - "revision": 2, + "revision": 3, "explanation": "Yes — the DC power formulas ($P = UI = U^2/R = I^2 R$) apply unchanged to AC across a purely resistive load, provided you use RMS (Effektivwert) values. RMS is defined precisely so that it produces the same heating as the equivalent DC; peak values would overstate the power by up to a factor of two.", - "source": "https://50ohm.de/EA_leistung_2.html", + "source": "https://50ohm.de/NEA_leistung_2.html#EB503", "confidence": 8 }, "EB504": { - "revision": 2, - "explanation": "Start from $P = U \\cdot I$ and substitute Ohm's law $I = U/R$ to eliminate the unknown current: $P = U^2/R$. Solving for the voltage gives $U = \\sqrt{P \\cdot R}$. (Option C, $\\sqrt{P/R}$, actually gives the current, not the voltage.)", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 3, + "explanation": "Start from $P = U \\cdot I$ and substitute Ohm's law $I = U/R$ to eliminate the unknown current: $P = U^2/R$. Solving for the voltage gives $U = \\sqrt{P \\cdot R}$. (Option C, $\\sqrt{P/R}$, actually gives the current, not the voltage.) Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB504", "confidence": 8 }, "EB505": { - "revision": 2, - "explanation": "For an ohmic load, use RMS values in the power formulas. From $P = I^2R$ you get $I = \\sqrt{P/R}$, and from $P = U^2/R$ you get $U = \\sqrt{PR}$.", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 3, + "explanation": "For an ohmic load, use RMS values in the power formulas. From $P = I^2R$ you get $I = \\sqrt{P/R}$, and from $P = U^2/R$ you get $U = \\sqrt{PR}$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB505", "confidence": 8 }, "EB506": { - "revision": 2, - "explanation": "These are just Ohm's law plus power rearranged. From $P = U^2/R$, $R = U^2/P$; from $P = I^2R$, $R = P/I^2$.", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 3, + "explanation": "These are just Ohm's law plus power rearranged. From $P = U^2/R$, $R = U^2/P$; from $P = I^2R$, $R = P/I^2$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB506", "confidence": 8 }, "EB507": { - "revision": 2, - "explanation": "For RF power in a resistive 50 Ohm load, use RMS voltage: $P = U^2/R$. With $U = 100 V$ and $R = 50 Ohm$, $P = 100^2/50 = 200 W$.", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 4, + "explanation": "For RF power in a resistive 50 Ohm load, use RMS voltage: $P = U^2/R$. With $U = 100 V$ and $R = 50 Ohm$, $P = 100^2/50 = 200 W$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB507", "confidence": 8 }, "EB508": { - "revision": 2, - "explanation": "Use RMS current in the resistive power formula $P = I^2R$. With $I = 2 A$ and $R = 50 Ohm$, $P = 2^2 \\cdot 50 = 200 W$.", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 4, + "explanation": "Use RMS current in the resistive power formula $P = I^2R$. With $I = 2 A$ and $R = 50 Ohm$, $P = 2^2 \\cdot 50 = 200 W$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB508", "confidence": 8 }, "EB509": { - "revision": 2, - "explanation": "With the voltage and resistance known, use $P = U^2/R = (10\\ \\text{V})^2 / 100\\ \\Omega = 100/100 = 1.00$ W. The resistor must be rated at least this, so a $1$ W part is the minimum.", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 4, + "explanation": "With the voltage and resistance known, use $P = U^2/R = (10\\ \\text{V})^2 / 100\\ \\Omega = 100/100 = 1.00$ W. The resistor must be rated at least this, so a $1$ W part is the minimum. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB509", "confidence": 8 }, "EB510": { - "revision": 2, - "explanation": "A resistor has two ceilings — voltage and power — and the lower allowed voltage wins. The power limit gives $U = \\sqrt{P \\cdot R} = \\sqrt{1\\ \\text{W} \\cdot 10000\\ \\Omega} = 100$ V. Since $100$ V is well below the $700$ V breakdown rating, power is the binding limit: max $100$ V.", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 4, + "explanation": "A resistor has two ceilings — voltage and power — and the lower allowed voltage wins. The power limit gives $U = \\sqrt{P \\cdot R} = \\sqrt{1\\ \\text{W} \\cdot 10000\\ \\Omega} = 100$ V. Since $100$ V is well below the $700$ V breakdown rating, power is the binding limit: max $100$ V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB510", "confidence": 8 }, "EB511": { - "revision": 2, - "explanation": "Check both ceilings and take the stricter. Power limit: $U = \\sqrt{P \\cdot R} = \\sqrt{6\\ \\text{W} \\cdot 100000\\ \\Omega} \\approx 775$ V. That is below the $1000$ V voltage rating, so the power rating binds first — the maximum is $\\approx 775$ V.", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 4, + "explanation": "Check both ceilings and take the stricter. Power limit: $U = \\sqrt{P \\cdot R} = \\sqrt{6\\ \\text{W} \\cdot 100000\\ \\Omega} \\approx 775$ V. That is below the $1000$ V voltage rating, so the power rating binds first — the maximum is $\\approx 775$ V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB511", "confidence": 8 }, "EB512": { - "revision": 2, - "explanation": "Solve $P = I^2R$ for current: $I = \\sqrt{P/R}$. With $P = 23.0 W$ and $R = 120 Ohm$, $I = \\sqrt{23/120} \\approx 0.438 A = 438 mA$.", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 4, + "explanation": "Solve $P = I^2R$ for current: $I = \\sqrt{P/R}$. With $P = 23.0 W$ and $R = 120 Ohm$, $I = \\sqrt{23/120} \\approx 0.438 A = 438 mA$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB512", "confidence": 8 }, "EB513": { - "revision": 2, - "explanation": "Convert the scope reading to RMS in steps: peak is half the peak-to-peak, $U_{\\text{pk}} = 25/2 = 12.5$ V; RMS of a sine is $U_{\\text{pk}}/\\sqrt{2} = 12.5/1.414 \\approx 8.84$ V. Then $I_{\\text{RMS}} = U/R = 8.84\\ \\text{V} / 1000\\ \\Omega \\approx 8.8$ mA.", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 4, + "explanation": "Convert the scope reading to RMS in steps: peak is half the peak-to-peak, $U_{\\text{pk}} = 25/2 = 12.5$ V; RMS of a sine is $U_{\\text{pk}}/\\sqrt{2} = 12.5/1.414 \\approx 8.84$ V. Then $I_{\\text{RMS}} = U/R = 8.84\\ \\text{V} / 1000\\ \\Omega \\approx 8.8$ mA. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB513", "confidence": 8 }, "EB514": { - "revision": 2, - "explanation": "Parallel resistors each dissipate independently, so power ratings add: $11 \\cdot 5\\ \\text{W} = 55$ W. (As a check, eleven $560\\ \\Omega$ in parallel give $560/11 \\approx 51\\ \\Omega \\approx 50\\ \\Omega$, the wanted dummy-load value.) The total handles much more than a single $5$ W resistor.", - "source": "https://50ohm.de/EA_leistung_2.html", + "revision": 4, + "explanation": "Parallel resistors each dissipate independently, so power ratings add: $11 \\cdot 5\\ \\text{W} = 55$ W. (As a check, eleven $560\\ \\Omega$ in parallel give $560/11 \\approx 51\\ \\Omega \\approx 50\\ \\Omega$, the wanted dummy-load value.) The total handles much more than a single $5$ W resistor. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung_2.html#EB514", "confidence": 8 }, "EC101": { - "revision": 2, + "revision": 3, "explanation": "Wirewound resistors (Drahtwiderstände) dissipate large power well, but the winding acts as a coil and adds inductance. That stray inductance is harmless at DC and low frequencies but spoils RF behaviour — so they suit high-power, low-frequency loads, not HF.", - "source": "https://50ohm.de/E_widerstand_materialien.html", + "source": "https://50ohm.de/NEA_widerstand_materialien.html#EC101", "confidence": 8 }, "EC102": { - "revision": 2, + "revision": 3, "explanation": "Metal-film resistors (Metallschichtwiderstände) are made with tight tolerance and a very low temperature coefficient, so their value barely drifts with manufacturing spread or heat. Those two properties are exactly what a precision resistor needs; wirewound is too inductive and LDRs change with light.", - "source": "https://50ohm.de/E_widerstand_materialien.html", + "source": "https://50ohm.de/NEA_widerstand_materialien.html#EC102", "confidence": 8 }, "EC103": { - "revision": 2, + "revision": 3, "explanation": "Metal-oxide film resistors (Metalloxidschichtwiderstände) are essentially non-inductive — no coil winding — so their impedance stays resistive above $30$ MHz. Wirewound parts behave like inductors at RF, which is why they are avoided there despite their power rating.", - "source": "https://50ohm.de/E_widerstand_materialien.html", + "source": "https://50ohm.de/NEA_widerstand_materialien.html#EC103", "confidence": 8 }, "EC104": { - "revision": 2, + "revision": 3, "explanation": "A dummy load (künstliche Antenne) must look like a pure $50\\ \\Omega$ resistance, presenting an SWR near 1 instead of radiating. Low self-inductance and self-capacitance keep the impedance resistive as frequency climbs into VHF/UHF; any reactance would skew it away from $50\\ \\Omega$.", - "source": "https://50ohm.de/E_widerstand_materialien.html", + "source": "https://50ohm.de/NEA_widerstand_materialien.html#EC104", "confidence": 8 }, "EC105": { - "revision": 2, + "revision": 3, "explanation": "Ten $500\\ \\Omega$ resistors in parallel give $500/10 = 50\\ \\Omega$, the wanted load value. Spreading the power over ten carbon-film parts also avoids the winding inductance of a single wirewound $50\\ \\Omega$ resistor, which would ruin the match at $28$ MHz.", - "source": "https://50ohm.de/E_widerstand_materialien.html", + "source": "https://50ohm.de/NEA_widerstand_materialien.html#EC105", "confidence": 8 }, "EC106": { - "revision": 2, + "revision": 3, "explanation": "Ten unwound $500\\ \\Omega$ carbon-film resistors in parallel give $500/10 = 50\\ \\Omega$, while staying low-inductance enough to behave resistively at $50$ MHz. A single wirewound $50\\ \\Omega$ part, or wound carbon parts, would add reactance and spoil the load.", - "source": "https://50ohm.de/E_widerstand_materialien.html", + "source": "https://50ohm.de/NEA_widerstand_materialien.html#EC106", "confidence": 8 }, "EC107": { - "revision": 2, + "revision": 3, "explanation": "For a VHF dummy load you want resistors that combine a clean resistive impedance with good power handling: unwound (non-inductive) metal-oxide resistors do both. High-power wirewound parts are too inductive at VHF, and reactive ('Blind') components by definition are not pure resistors.", - "source": "https://50ohm.de/E_widerstand_materialien.html", + "source": "https://50ohm.de/NEA_widerstand_materialien.html#EC107", "confidence": 8 }, "EC108": { - "revision": 2, + "revision": 3, "explanation": "An NTC thermistor is a temperature-dependent resistor with a Negative Temperature Coefficient: as temperature rises, resistance falls. That predictable resistance change lets the circuit infer temperature from a resistance or voltage-divider measurement.", - "source": "https://50ohm.de/E_widerstand_ntc_ptc.html", + "source": "https://50ohm.de/NEA_widerstand_ntc_ptc.html#EC108", "confidence": 8 }, "EC109": { - "revision": 2, + "revision": 3, "explanation": "NTC means negative temperature coefficient: as temperature rises, resistance falls. The matching symbol is therefore the temperature-dependent resistor whose resistance trend goes downward with heat.", - "source": "https://50ohm.de/E_widerstand_ntc_ptc.html", + "source": "https://50ohm.de/NEA_widerstand_ntc_ptc.html#EC109", "confidence": 8 }, "EC110": { - "revision": 2, + "revision": 3, "explanation": "For an NTC thermistor, hotter means lower resistance. In the symbol choices, look for the temperature indication rising while the resistance indication falls; that is the negative coefficient.", - "source": "https://50ohm.de/E_widerstand_ntc_ptc.html", + "source": "https://50ohm.de/NEA_widerstand_ntc_ptc.html#EC110", "confidence": 8 }, "EC111": { - "revision": 2, + "revision": 3, "explanation": "PTC means positive temperature coefficient: resistance increases with temperature. The right symbol is the one where heating and resistance go in the same upward direction.", - "source": "https://50ohm.de/E_widerstand_ntc_ptc.html", + "source": "https://50ohm.de/NEA_widerstand_ntc_ptc.html#EC111", "confidence": 8 }, "EC112": { - "revision": 2, + "revision": 3, "explanation": "A $10\\,\\%$ tolerance means $\\pm 0.10 \\cdot 5.6\\ \\text{k}\\Omega = \\pm 0.56\\ \\text{k}\\Omega = \\pm 560\\ \\Omega$. So the true value lies in $5600 \\pm 560\\ \\Omega$, i.e. $5040$ to $6160\\ \\Omega$. The wider/narrower options use the wrong tolerance band.", - "source": "https://50ohm.de/NE_widerstand_toleranz.html", + "source": "https://50ohm.de/NEA_widerstand_toleranz.html#EC112", "confidence": 8 }, "EC113": { - "revision": 2, + "revision": 3, "explanation": "Read the colour bands (Farbringe): green $= 5$, blue $= 6$, red $= \\times 100$, so the nominal value is $56 \\cdot 100 = 5600\\ \\Omega$. The silver band is $\\pm 10\\,\\%$, i.e. $\\pm 560\\ \\Omega$, giving $5040$ to $6160\\ \\Omega$ — the same maths as a stated $10\\,\\%$ tolerance.", - "source": "https://50ohm.de/NE_widerstand_toleranz.html", + "source": "https://50ohm.de/NEA_widerstand_toleranz.html#EC113", "confidence": 8 }, "EC114": { - "revision": 2, + "revision": 3, "explanation": "Three-digit SMD codes work like the colour code in numbers: the first digits are significant figures and the last digit is the power-of-ten multiplier (e.g. $472 = 47 \\cdot 10^2 = 4700\\ \\Omega$). SMD chips are too small for colour rings, so a printed-number scheme is used.", - "source": "https://50ohm.de/E_widerstand_smd.html", + "source": "https://50ohm.de/NEA_widerstand_smd.html#EC114", "confidence": 8 }, "EC115": { - "revision": 2, + "revision": 3, "explanation": "Three-digit SMD resistor codes use the first two digits as significant figures and the third as the zero count. `103` means $10 \\cdot 10^3 Ohm = 10,000 Ohm = 10 kOhm$.", - "source": "https://50ohm.de/E_widerstand_smd.html", + "source": "https://50ohm.de/NEA_widerstand_smd.html#EC115", "confidence": 8 }, "EC116": { - "revision": 2, + "revision": 3, "explanation": "For SMD marking `221`, the significant digits are 22 and the multiplier digit 1 means one zero. So $22 \\cdot 10^1 Ohm = 220 Ohm$.", - "source": "https://50ohm.de/E_widerstand_smd.html", + "source": "https://50ohm.de/NEA_widerstand_smd.html#EC116", "confidence": 8 }, "EC117": { - "revision": 2, + "revision": 3, "explanation": "The SMD code `223` means 22 with three zeros after it: $22 \\cdot 10^3 Ohm = 22,000 Ohm = 22 kOhm$.", - "source": "https://50ohm.de/E_widerstand_smd.html", + "source": "https://50ohm.de/NEA_widerstand_smd.html#EC117", "confidence": 8 }, "EC201": { - "revision": 2, + "revision": 3, "explanation": "A capacitor voltage cannot jump instantly; it charges through the resistor with an RC time constant $\\tau = RC$. Current is largest at first, then falls as the capacitor voltage approaches the supply, producing a rising exponential curve.", - "source": "https://50ohm.de/EA_kondensator_1.html", + "source": "https://50ohm.de/NEA_kondensator_1.html#EC201", "confidence": 8 }, "EC202": { - "revision": 2, + "revision": 3, "explanation": "A capacitor's AC reactance is $X_C = 1/(2\\pi f C)$ — inversely proportional to frequency. So as frequency rises, an ideal capacitor's opposition to AC steadily falls: it increasingly looks like a short circuit to high frequencies, which is exactly how coupling and bypass capacitors work.", - "source": "https://50ohm.de/EA_kondensator_1.html", + "source": "https://50ohm.de/NEA_kondensator_1.html#EC202", "confidence": 8 }, "EC203": { - "revision": 2, + "revision": 3, "explanation": "Plate-capacitor capacitance is $C = \\varepsilon_0 \\varepsilon_r A / d$ — proportional to plate area $A$ and dielectric constant $\\varepsilon_r$, inversely proportional to the gap $d$. Increasing the spacing $d$ is therefore the way to reduce capacitance; larger area or higher $\\varepsilon_r$ would increase it, and applied voltage does not change $C$ at all.", - "source": "https://50ohm.de/EA_kondensator_1.html", + "source": "https://50ohm.de/NEA_kondensator_1.html#EC203", "confidence": 8 }, "EC204": { - "revision": 2, + "revision": 3, "explanation": "For a plate capacitor, $C=\\varepsilon A/d$: capacitance rises with plate area and permittivity, but falls when plate spacing $d$ increases. Moving the same plates farther apart weakens their electric-field coupling, so capacitance decreases.", - "source": "https://50ohm.de/EA_kondensator_1.html", + "source": "https://50ohm.de/NEA_kondensator_1.html#EC204", "confidence": 8 }, "EC205": { - "revision": 2, + "revision": 3, "explanation": "For an ideal plate capacitor, $C=\\varepsilon A/d$. Geometry and dielectric material set the capacitance; the applied voltage only changes stored charge by $Q=CU$, not the capacitance itself.", - "source": "https://50ohm.de/EA_kondensator_1.html", + "source": "https://50ohm.de/NEA_kondensator_1.html#EC205", "confidence": 8 }, "EC206": { - "revision": 2, + "revision": 3, "explanation": "A component whose rotor plates turn on an insulated shaft between fixed stator plates is a variable/tuning capacitor (Drehkondensator). Rotating the rotor changes how much plate area overlaps, and since $C \\propto A$, that varies the capacitance — the classic way to tune an LC resonant circuit.", - "source": "https://50ohm.de/EA_kondensator_1.html", + "source": "https://50ohm.de/NEA_kondensator_1.html#EC206", "confidence": 8 }, "EC207": { - "revision": 2, + "revision": 3, "explanation": "Electrolytic capacitors are polarized because the thin oxide dielectric is formed and maintained only with the correct DC polarity. Reverse voltage can destroy that oxide, causing high leakage, heating, gas pressure, or failure.", - "source": "https://50ohm.de/EA_kondensator_1.html", + "source": "https://50ohm.de/NEA_kondensator_1.html#EC207", "confidence": 8 }, "EC301": { - "revision": 2, + "revision": 3, "explanation": "An inductor resists changes in current: $u_L = L \\cdot di/dt$. Right after switch-on, current is changing fastest and the inductor voltage is high; once steady DC flows, $di/dt$ becomes zero and the inductor voltage decays toward zero.", - "source": "https://50ohm.de/EA_spule_1.html", + "source": "https://50ohm.de/NEA_spule_1.html#EC301", "confidence": 8 }, "EC302": { - "revision": 2, + "revision": 3, "explanation": "An inductor opposes any change in current via its self-induced voltage, $u_L = L \\cdot di/dt$. At switch-on the iron-cored, many-turn coil briefly blocks the current, so lamp 2 ramps up slowly while lamp 1 — fed through a plain resistor — lights first. The coil only delays the current; it does not stop it, so lamp 2 follows shortly after.", - "source": "https://50ohm.de/EA_spule_1.html", + "source": "https://50ohm.de/NEA_spule_1.html#EC302", "confidence": 8 }, "EC303": { - "revision": 2, + "revision": 3, "explanation": "An ideal inductor's reactance is $X_L = 2\\pi f L$ — directly proportional to frequency. So its opposition to AC rises with frequency: an inductor increasingly blocks high frequencies, the mirror image of a capacitor. This is why RF chokes (Drosseln) work.", - "source": "https://50ohm.de/EA_spule_1.html", + "source": "https://50ohm.de/NEA_spule_1.html#EC303", "confidence": 8 }, "EC304": { - "revision": 2, + "revision": 3, "explanation": "Every conductor carrying current sets up a magnetic field and therefore stores some magnetic energy, which is exactly what inductance measures — so even a straight piece of wire has inductance (a few nH per cm). No curvature or winding is required; at VHF/UHF that lead inductance already matters.", - "source": "https://50ohm.de/E_spule_1.html", + "source": "https://50ohm.de/NEA_spule_1.html#EC304", "confidence": 8 }, "EC305": { - "revision": 2, + "revision": 3, "explanation": "Coil inductance follows $L = \\mu_0 \\mu_r N^2 A / l$. Squeezing the cylindrical coil shorter (smaller $l$) at unchanged turns raises $L$. A copper core would lower $L$ (eddy currents oppose the flux), and a shield can also reduce it — so only compressing the winding increases inductance.", - "source": "https://50ohm.de/EA_spule_1.html", + "source": "https://50ohm.de/NEA_spule_1.html#EC305", "confidence": 8 }, "EC306": { - "revision": 2, - "explanation": "With turns $N$ and cross-section $A$ held fixed, $L = \\mu_0 \\mu_r N^2 A / l$ is inversely proportional to length $l$. Doubling the length halves the inductance: $12\\ \\mu\\text{H} / 2 = 6\\ \\mu\\text{H}$.", - "source": "https://50ohm.de/EA_spule_1.html", + "revision": 4, + "explanation": "With turns $N$ and cross-section $A$ held fixed, $L = \\mu_0 \\mu_r N^2 A / l$ is inversely proportional to length $l$. Doubling the length halves the inductance: $12\\ \\mu\\text{H} / 2 = 6\\ \\mu\\text{H}$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spule_1.html#EC306", "confidence": 8 }, "EC307": { - "revision": 2, + "revision": 3, "explanation": "Inductance grows with the square of the turns: $L \\propto N^2$. Doubling the turns (same winding length) multiplies $L$ by $2^2 = 4$, so $12\\ \\mu\\text{H} \\cdot 4 = 48\\ \\mu\\text{H}$. That $N^2$ dependence is why adding a few turns changes $L$ sharply.", - "source": "https://50ohm.de/EA_spule_1.html", + "source": "https://50ohm.de/NEA_spule_1.html#EC307", "confidence": 8 }, "EC401": { - "revision": 2, - "explanation": "An ideal transformer scales voltage by turns ratio: $U_1/U_2 = N_1/N_2$. A 15:1 primary-to-secondary ratio steps 230 V down to $230/15 \\approx 15.3 V$, so about 15 V.", - "source": "https://50ohm.de/E_uebertrager_1.html", + "revision": 4, + "explanation": "An ideal transformer scales voltage by turns ratio: $U_1/U_2 = N_1/N_2$. A 15:1 primary-to-secondary ratio steps 230 V down to $230/15 \\approx 15.3 V$, so about 15 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_uebertrager_1.html#EC401", "confidence": 8 }, "EC402": { - "revision": 2, - "explanation": "An ideal transformer scales voltage by the turns ratio: $U_2/U_1 = N_2/N_1$. With the primary having five times the secondary's turns, the secondary voltage is one fifth: $230\\ \\text{V} / 5 = 46$ V. More turns means more volts on that side.", - "source": "https://50ohm.de/E_uebertrager_1.html", + "revision": 4, + "explanation": "An ideal transformer scales voltage by the turns ratio: $U_2/U_1 = N_2/N_1$. With the primary having five times the secondary's turns, the secondary voltage is one fifth: $230\\ \\text{V} / 5 = 46$ V. More turns means more volts on that side. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_uebertrager_1.html#EC402", "confidence": 8 }, "EC403": { - "revision": 2, + "revision": 3, "explanation": "For an ideal transformer, voltage ratio equals turns ratio: $U_1/U_2 = N_1/N_2$. Here $230/11.5 = 20$, so the secondary has $N_2 = 600/20 = 30$ turns.", - "source": "https://50ohm.de/E_uebertrager_1.html", + "source": "https://50ohm.de/NEA_uebertrager_1.html#EC403", "confidence": 8 }, "EC404": { - "revision": 2, + "revision": 3, "explanation": "Turns follow the voltage ratio, $N_2/N_1 = U_2/U_1$. Here $U_2/U_1 = 180/45 = 4$, so the secondary needs four times the primary turns: $N_2 = 150 \\cdot 4 = 600$ turns. A step-up in voltage means a step-up in turns.", - "source": "https://50ohm.de/E_uebertrager_1.html", + "source": "https://50ohm.de/NEA_uebertrager_1.html#EC404", "confidence": 8 }, "EC501": { - "revision": 2, + "revision": 3, "explanation": "A diode conducts only above its forward threshold; biased the other way (reverse, Sperrrichtung) it passes just a tiny leakage current. Very little current for an applied voltage means $R = U/I$ is very large — the diode looks like a high resistance, effectively an open switch.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC501", "confidence": 8 }, "EC502": { - "revision": 2, + "revision": 3, "explanation": "A diode conducts in only one direction, so it passes one polarity of an AC half-cycle and blocks the other. That one-way action is exactly what rectification (Gleichrichtung) needs — turning AC into pulsating DC in power supplies and detectors. It cannot amplify or store, so the other options are out.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC502", "confidence": 8 }, "EC503": { - "revision": 2, + "revision": 3, "explanation": "Forward threshold (Schwellspannung) depends on the semiconductor: germanium conducts from about $0.2$-$0.4$ V, silicon from about $0.6$-$0.8$ V. The lower germanium drop is why crystal/detector receivers favour Ge or Schottky diodes for weak signals. Option B simply swaps the two materials.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC503", "confidence": 8 }, "EC504": { - "revision": 2, + "revision": 3, "explanation": "A Schottky diode uses a metal-semiconductor junction instead of a pn junction. That gives a low forward voltage (around $0.3$ V) and — because it has almost no minority-carrier storage charge — extremely fast switching, making it ideal for HF mixers, detectors, and switch-mode rectifiers.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC504", "confidence": 8 }, "EC505": { - "revision": 2, + "revision": 3, "explanation": "A Schottky diode has the lowest forward voltage because it uses a metal-semiconductor junction rather than a pn junction. On the characteristic plot, the curve that starts conducting at the lowest voltage is therefore Schottky.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC505", "confidence": 8 }, "EC506": { - "revision": 2, + "revision": 3, "explanation": "Germanium pn diodes conduct at a lower forward voltage than silicon, typically around 0.2-0.4 V. So the curve above Schottky but below silicon is the germanium diode.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC506", "confidence": 8 }, "EC507": { - "revision": 2, + "revision": 3, "explanation": "A normal silicon diode needs about 0.6-0.8 V forward bias before current rises steeply. The curve with that knee voltage is the silicon diode.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC507", "confidence": 8 }, "EC508": { - "revision": 2, + "revision": 3, "explanation": "An LED has a higher forward voltage because electron-hole recombination releases photon energy. On the plot, the curve with the highest forward threshold is the light-emitting diode.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC508", "confidence": 8 }, "EC509": { - "revision": 2, + "revision": 3, "explanation": "For a silicon diode to conduct, the anode must be about 0.7 V above the cathode. Here the anode-cathode difference is $1.3 V - 0.6 V = 0.7 V$, so it is forward-biased.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC509", "confidence": 8 }, "EC510": { - "revision": 2, + "revision": 3, "explanation": "Use voltage difference, not absolute voltage. The selected case has the anode at $0.3 V$ and cathode at $-0.4 V$, so $U_A-U_K = 0.7 V$ and the silicon diode conducts.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC510", "confidence": 8 }, "EC511": { - "revision": 2, + "revision": 3, "explanation": "Forward bias depends on relative voltage. Even though both nodes are negative, $-1.3 V$ at the anode is $0.7 V$ higher than $-2.0 V$ at the cathode, so the silicon diode conducts.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC511", "confidence": 8 }, "EC512": { - "revision": 2, + "revision": 3, "explanation": "The silicon-diode test is $U_A - U_K \\approx 0.7 V$. In the selected drawing, $-3.0 V - (-3.7 V) = 0.7 V$, so the anode is sufficiently above the cathode.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC512", "confidence": 8 }, "EC513": { - "revision": 2, + "revision": 3, "explanation": "A silicon diode conducts when the anode is about $0.7$ V above the cathode (forward bias). Check each pair by anode minus cathode: $5.7\\ \\text{V} - 5.0\\ \\text{V} = +0.7$ V, which just meets the threshold. The others give $-0.7$ V, $-0.1$ V, or $-0.7$ V — reverse-biased or below threshold.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC513", "confidence": 8 }, "EC514": { - "revision": 2, + "revision": 3, "explanation": "The outgoing arrows identify an LED (light-emitting diode). The series resistor is essential because the diode voltage is roughly fixed once conducting; the resistor limits current to a safe value.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC514", "confidence": 8 }, "EC515": { - "revision": 2, + "revision": 3, "explanation": "The series resistor (Vorwiderstand) drops the supply voltage that the LED does not: $5.0\\ \\text{V} - 1.4\\ \\text{V} = 3.6$ V. By Ohm's law at the wanted current, $R = U/I = 3.6\\ \\text{V} / 0.020\\ \\text{A} = 180\\ \\Omega$. The LED itself sets the current via this resistor, since its own voltage is nearly fixed.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC515", "confidence": 8 }, "EC516": { - "revision": 2, - "explanation": "The resistor takes the difference between supply and LED voltage: $5.5\\ \\text{V} - 1.75\\ \\text{V} = 3.75$ V. So $R = 3.75\\ \\text{V} / 0.025\\ \\text{A} = 150\\ \\Omega$. Its power dissipation is $P = U \\cdot I = 3.75\\ \\text{V} \\cdot 0.025\\ \\text{A} \\approx 0.094$ W, so a $0.1$ W resistor is the smallest standard rating that survives.", - "source": "https://50ohm.de/EA_diode_1.html", + "revision": 4, + "explanation": "The resistor takes the difference between supply and LED voltage: $5.5\\ \\text{V} - 1.75\\ \\text{V} = 3.75$ V. So $R = 3.75\\ \\text{V} / 0.025\\ \\text{A} = 150\\ \\Omega$. Its power dissipation is $P = U \\cdot I = 3.75\\ \\text{V} \\cdot 0.025\\ \\text{A} \\approx 0.094$ W, so a $0.1$ W resistor is the smallest standard rating that survives. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_diode_1.html#EC516", "confidence": 8 }, "EC517": { - "revision": 2, + "revision": 3, "explanation": "A Zener diode is drawn like a diode with a bent cathode bar. That symbol hints at its special use: reverse breakdown at a defined voltage for voltage limiting or stabilisation.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC517", "confidence": 8 }, "EC518": { - "revision": 2, + "revision": 3, "explanation": "A Zener diode (Z-Diode) is run in reverse breakdown, where it holds an almost constant voltage over a wide current range. That fixed-voltage behaviour makes it a simple voltage reference/stabiliser (Spannungsstabilisierung) — it pins a voltage, not a current.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC518", "confidence": 8 }, "EC519": { - "revision": 2, + "revision": 3, "explanation": "A simple Zener stabiliser is a shunt regulator: the series resistor limits current, and the reverse-biased Zener sits across the output to clamp the voltage near its Zener voltage.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC519", "confidence": 8 }, "EC520": { - "revision": 2, + "revision": 3, "explanation": "For a positive shunt regulator, the Zener diode is reverse-biased across the output after a series resistor. When voltage tries to rise above the Zener voltage, the diode conducts more and clamps it.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC520", "confidence": 8 }, "EC521": { - "revision": 2, - "explanation": "With no load, the series resistor carries only the Zener current and must drop the supply down to the Zener voltage: $13.8\\ \\text{V} - 5\\ \\text{V} = 8.8$ V across it at $30$ mA. So $R = 8.8\\ \\text{V} / 0.030\\ \\text{A} \\approx 293\\ \\Omega$. (Option B's milliohm value would short the supply — a sanity-check fail.)", - "source": "https://50ohm.de/EA_diode_1.html", + "revision": 3, + "explanation": "With no load, the series resistor carries only the Zener current and must drop the supply down to the Zener voltage: $13.8\\ \\text{V} - 5\\ \\text{V} = 8.8$ V across it at $30$ mA. So $R = 8.8\\ \\text{V} / 0.030\\ \\text{A} \\approx 293\\ \\Omega$. (Option B's milliohm value would short the supply — a sanity-check fail.) Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_diode_1.html#EC521", "confidence": 8 }, "EC522": { - "revision": 2, + "revision": 3, "explanation": "The series resistor carries both the Zener current and the load current: $25\\ \\text{mA} + 20\\ \\text{mA} = 45$ mA. From the schematic's $13.8$ V supply and $4.7$ V stabilised output it drops $13.8 - 4.7 = 9.1$ V, so $R = 9.1\\ \\text{V} / 0.045\\ \\text{A} \\approx 202\\ \\Omega$. The resistor must be sized for the worst case where the load draws nothing and all $45$ mA flows in the Zener.", - "source": "https://50ohm.de/EA_diode_1.html", + "source": "https://50ohm.de/NEA_diode_1.html#EC522", "confidence": 8 }, "EC601": { - "revision": 2, + "revision": 3, "explanation": "A transistor can be driven into saturation or cut-off to act as a switch, biased in its linear region to act as an amplifier, or used as a voltage-controlled resistance. That versatility is unique to the transistor here — a transformer, capacitor, or diode cannot amplify.", - "source": "https://50ohm.de/NEA_transistor_1.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC601", "confidence": 8 }, "EC602": { - "revision": 2, + "revision": 3, "explanation": "A transistor is a semiconductor device (Halbleiterbauelement): a bipolar type is built from three alternating n- and p-doped zones (NPN or PNP). Its controllable conduction comes precisely from the physics of those doped semiconductor junctions, not from being an insulator or a simple conductor.", - "source": "https://50ohm.de/NEA_transistor_1.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC602", "confidence": 8 }, "EC603": { - "revision": 2, + "revision": 3, "explanation": "Current gain (Stromverstärkung) means a small base current steers a much larger collector current, $I_C = \\beta \\cdot I_B$, with $\\beta$ (hFE) often around 100-300. The base acts as the control input; the collector-emitter path carries the controlled output current.", - "source": "https://50ohm.de/NEA_transistor_1.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC603", "confidence": 8 }, "EC604": { - "revision": 2, + "revision": 3, "explanation": "Bipolar junction transistors (BJTs) come in just two polarities: NPN and PNP, named for their doped-layer order. All the FET names — MOSFET, dual-gate MOS, junction-FET (JFET) — are field-effect transistors, a different family that is voltage- rather than current-controlled.", - "source": "https://50ohm.de/NEA_transistor_1.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC604", "confidence": 8 }, "EC605": { - "revision": 3, + "revision": 4, "explanation": "A bipolar junction transistor (BJT) symbol is identified by its three terminals base, collector, and emitter, plus the arrow on the emitter. Field-effect transistors (FETs) use gate, drain, and source instead, so the terminal names alone already separate the symbol families.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC605", "confidence": 8 }, "EC606": { - "revision": 3, + "revision": 4, "explanation": "In an NPN BJT, conventional emitter current leaves the transistor symbol, so the emitter arrow points outward. The common English mnemonic is 'NPN: Not Pointing iN'.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC606", "confidence": 8 }, "EC607": { - "revision": 3, + "revision": 4, "explanation": "In a PNP BJT, conventional emitter current enters the transistor symbol, so the emitter arrow points inward toward the base region. 50ohm's German memory aid is 'PNP: Pfeil Nach Platte'.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC607", "confidence": 8 }, "EC608": { - "revision": 2, + "revision": 3, "explanation": "A bipolar transistor's three terminals are emitter, base, and collector (Emitter, Basis, Kollektor). Drain, source, and gate are the terminals of a field-effect transistor instead — mixing the two naming sets is the trap in the other options.", - "source": "https://50ohm.de/NEA_transistor_1.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC608", "confidence": 8 }, "EC609": { - "revision": 3, + "revision": 4, "explanation": "Read a BJT symbol by finding the base line first and then the emitter arrow. In the shown NPN symbol, terminal 2 is the base, terminal 3 is the emitter because it carries the outward arrow, and terminal 1 is therefore the collector.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC609", "confidence": 8 }, "EC610": { - "revision": 4, - "explanation": "A silicon BJT conducts once its base-emitter junction is forward-biased past the silicon threshold, about $0.6$-$0.7$ V, so $U_{BE} \\approx 0.6$ V (positive for an NPN). A negative or zero $U_{BE}$ leaves the junction off, so those options do not turn it on.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "revision": 5, + "explanation": "A silicon BJT conducts once its base-emitter junction is forward-biased past the silicon threshold, about $0.6$-$0.7$ V, so $U_{BE} \\approx 0.6$ V (positive for an NPN). A negative or zero $U_{BE}$ leaves the junction off, so those options do not turn it on. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_transistor_1.html#EC610", "confidence": 8 }, "EC611": { - "revision": 2, + "revision": 3, "explanation": "Kirchhoff's current law at the transistor gives $I_E = I_C + I_B$: the emitter current is the sum of the other two. Since base current is tiny and collector current large, the emitter necessarily carries the most current of the three terminals.", - "source": "https://50ohm.de/NEA_transistor_1.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC611", "confidence": 8 }, "EC612": { - "revision": 3, + "revision": 4, "explanation": "An NPN BJT conducts when its silicon base-emitter junction is forward biased, so $V_B - V_E \\approx +0.6 V$. The selected drawing has +2.0 V at the base and +1.4 V at the emitter, exactly the needed forward bias.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC612", "confidence": 8 }, "EC613": { - "revision": 3, + "revision": 4, "explanation": "For an NPN transistor, compare base to emitter, not either point to ground: $V_{BE}=V_B-V_E$. Here $-5.6 V - (-6.2 V)=+0.6 V$, so the base-emitter junction is forward biased and collector current can flow.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC613", "confidence": 8 }, "EC614": { - "revision": 3, + "revision": 4, "explanation": "A PNP BJT is the polarity mirror of an NPN: it conducts when the base is about 0.6 V lower than the emitter, so $V_B - V_E \\approx -0.6 V$. The selected drawing has -2.0 V at the base and -1.4 V at the emitter.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC614", "confidence": 8 }, "EC615": { - "revision": 3, + "revision": 4, "explanation": "For a PNP transistor the conducting condition is $V_{BE}\\approx -0.6 V$, meaning the base is 0.6 V below the emitter. Here $+5.6 V - +6.2 V = -0.6 V$, so the base-emitter junction is correctly forward biased.", - "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "source": "https://50ohm.de/NEA_transistor_1.html#EC615", "confidence": 8 }, "ED101": { - "revision": 2, - "explanation": "Series resistors carry the same current, so by $U = R \\cdot I$ the voltages split in the resistance ratio: $U_1/U_2 = R_1/R_2$. With $R_1 = 5 R_2$, $U_1 = 5\\,U_2$ — the larger resistor drops the larger voltage.", - "source": "https://50ohm.de/NE_spannungsteiler_1.html", + "revision": 3, + "explanation": "Series resistors carry the same current, so by $U = R \\cdot I$ the voltages split in the resistance ratio: $U_1/U_2 = R_1/R_2$. With $R_1 = 5 R_2$, $U_1 = 5\\,U_2$ — the larger resistor drops the larger voltage. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsteiler_1.html#ED101", "confidence": 8 }, "ED102": { - "revision": 2, - "explanation": "In a series divider the voltage ratio equals the resistance ratio, $U_1/U_2 = R_1/R_2$. Here $R_1 = R_2/6$, so $U_1 = U_2/6$ — the smaller resistor drops proportionally less voltage.", - "source": "https://50ohm.de/NE_spannungsteiler_1.html", + "revision": 3, + "explanation": "In a series divider the voltage ratio equals the resistance ratio, $U_1/U_2 = R_1/R_2$. Here $R_1 = R_2/6$, so $U_1 = U_2/6$ — the smaller resistor drops proportionally less voltage. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsteiler_1.html#ED102", "confidence": 8 }, "ED103": { - "revision": 2, - "explanation": "Use the divider rule $U_2 = U \\cdot R_2/(R_1 + R_2)$. With $U = 9$ V, $R_1 = 10\\ \\text{k}\\Omega$, $R_2 = 20\\ \\text{k}\\Omega$: $U_2 = 9 \\cdot 20/(10+20) = 9 \\cdot 20/30 = 6.0$ V. The bigger resistor takes the bigger share.", - "source": "https://50ohm.de/NE_spannungsteiler_1.html", + "revision": 3, + "explanation": "Use the divider rule $U_2 = U \\cdot R_2/(R_1 + R_2)$. With $U = 9$ V, $R_1 = 10\\ \\text{k}\\Omega$, $R_2 = 20\\ \\text{k}\\Omega$: $U_2 = 9 \\cdot 20/(10+20) = 9 \\cdot 20/30 = 6.0$ V. The bigger resistor takes the bigger share. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsteiler_1.html#ED103", "confidence": 8 }, "ED104": { - "revision": 2, - "explanation": "For two parallel resistors use $R_g = R_1R_2/(R_1+R_2)$, because conductances add in parallel. With 100 Ohm and 400 Ohm: $100\\cdot400/(100+400)=40000/500=80 Ohm$.", - "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "revision": 3, + "explanation": "For two parallel resistors use $R_g = R_1R_2/(R_1+R_2)$, because conductances add in parallel. With 100 Ohm and 400 Ohm: $100\\cdot400/(100+400)=40000/500=80 Ohm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstand.html#ED104", "confidence": 8 }, "ED105": { - "revision": 2, - "explanation": "Parallel resistance is always lower than the smallest branch. For two branches use $R_g = R_1R_2/(R_1+R_2)$: $50\\cdot200/(50+200)=10000/250=40 Ohm$.", - "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "revision": 3, + "explanation": "Parallel resistance is always lower than the smallest branch. For two branches use $R_g = R_1R_2/(R_1+R_2)$: $50\\cdot200/(50+200)=10000/250=40 Ohm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstand.html#ED105", "confidence": 8 }, "ED106": { - "revision": 2, + "revision": 3, "explanation": "For $n$ equal resistors in parallel the total is $R_g = R/n$, so a single resistor is $R = n \\cdot R_g$. Here $R = 3 \\cdot 1.7\\ \\text{k}\\Omega = 5.1\\ \\text{k}\\Omega$. (Parallel resistance is always smaller than the smallest resistor, which it is.)", - "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstand.html#ED106", "confidence": 8 }, "ED107": { - "revision": 2, + "revision": 3, "explanation": "Power ratings add when several resistors share the load, regardless of how they are wired: the assembly dissipates $3 \\cdot 1\\ \\text{W} = 3$ W in both series and parallel. Series or parallel changes the total resistance, not the total heat the three parts can shed.", - "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstand.html#ED107", "confidence": 8 }, "ED108": { - "revision": 2, - "explanation": "Reduce mixed resistor networks one obvious block at a time. Series resistors add directly: $500 + 500 = 1000 Ohm$. That 1000 Ohm branch is parallel with another 1000 Ohm resistor, and two equal parallel resistors halve: $1000/2 = 500 Ohm$.", - "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "revision": 3, + "explanation": "Reduce mixed resistor networks one obvious block at a time. Series resistors add directly: $500 + 500 = 1000 Ohm$. That 1000 Ohm branch is parallel with another 1000 Ohm resistor, and two equal parallel resistors halve: $1000/2 = 500 Ohm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstand.html#ED108", "confidence": 8 }, "ED109": { - "revision": 2, - "explanation": "First combine the series path: $500 Ohm + 1.5 kOhm = 2 kOhm$. That branch is parallel to another 2 kOhm branch, and equal parallel resistors give half the value, so $R_g = 1 kOhm$.", - "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "revision": 3, + "explanation": "First combine the series path: $500 Ohm + 1.5 kOhm = 2 kOhm$. That branch is parallel to another 2 kOhm branch, and equal parallel resistors give half the value, so $R_g = 1 kOhm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstand.html#ED109", "confidence": 8 }, "ED110": { - "revision": 2, - "explanation": "Parallel branches have the same voltage; for two equal 1 kOhm resistors the equivalent is $1 kOhm / 2 = 500 Ohm$. Add the remaining 500 Ohm series resistor and the total becomes $500 + 500 = 1000 Ohm$.", - "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "revision": 3, + "explanation": "Parallel branches have the same voltage; for two equal 1 kOhm resistors the equivalent is $1 kOhm / 2 = 500 Ohm$. Add the remaining 500 Ohm series resistor and the total becomes $500 + 500 = 1000 Ohm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstand.html#ED110", "confidence": 8 }, "ED111": { - "revision": 2, - "explanation": "Start with the parallel part: two equal 2 kOhm resistors in parallel give $2 kOhm / 2 = 1 kOhm$. That equivalent is then in series with R1, so $1 kOhm + 1 kOhm = 2 kOhm$.", - "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "revision": 3, + "explanation": "Start with the parallel part: two equal 2 kOhm resistors in parallel give $2 kOhm / 2 = 1 kOhm$. That equivalent is then in series with R1, so $1 kOhm + 1 kOhm = 2 kOhm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstand.html#ED111", "confidence": 8 }, "ED112": { - "revision": 2, - "explanation": "For two unequal parallel resistors use $R_g = R_1R_2/(R_1+R_2)$. Thus $3 kOhm || 1.5 kOhm = 4.5/4.5 kOhm = 1 kOhm$, and the series R1 adds another 1 kOhm for a total of 2 kOhm.", - "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "revision": 3, + "explanation": "For two unequal parallel resistors use $R_g = R_1R_2/(R_1+R_2)$. Thus $3 kOhm || 1.5 kOhm = 4.5/4.5 kOhm = 1 kOhm$, and the series R1 adds another 1 kOhm for a total of 2 kOhm. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstand.html#ED112", "confidence": 8 }, "ED113": { - "revision": 2, - "explanation": "Use reciprocal addition for three parallel resistors: $1/R = 1/10 kOhm + 1/2.5 kOhm + 1/500 Ohm$, giving 400 Ohm. The remaining 600 Ohm is in series, so the total is $400 + 600 = 1000 Ohm$.", - "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "revision": 3, + "explanation": "Use reciprocal addition for three parallel resistors: $1/R = 1/10 kOhm + 1/2.5 kOhm + 1/500 Ohm$, giving 400 Ohm. The remaining 600 Ohm is in series, so the total is $400 + 600 = 1000 Ohm$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstand.html#ED113", "confidence": 8 }, "ED114": { - "revision": 2, + "revision": 3, "explanation": "Do not try to see the whole network at once; replace one series/parallel group by its equivalent, then repeat. Here $50+50=100 Ohm$, that 100 Ohm in parallel with 100 Ohm becomes 50 Ohm, and the remaining series values add to 250 Ohm.", - "source": "https://50ohm.de/NE_reihe_parallel_widerstandsnetz_1.html", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstandsnetz_1.html#ED114", "confidence": 8 }, "ED115": { - "revision": 2, + "revision": 3, "explanation": "The method is staged simplification: series groups add directly, parallel groups use reciprocal addition or the equal-resistor shortcut. After replacing the drawn subgroups by their equivalents, the remaining series chain sums to 550 Ohm.", - "source": "https://50ohm.de/NE_reihe_parallel_widerstandsnetz_1.html", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstandsnetz_1.html#ED115", "confidence": 8 }, "ED116": { - "revision": 2, + "revision": 3, "explanation": "After each visible series/parallel block is replaced by its equivalent, the network no longer has branches: it is a series chain. The remaining values are 400 Ohm, 200 Ohm, 200 Ohm, and 150 Ohm, so $R_g = 950 Ohm$.", - "source": "https://50ohm.de/NE_reihe_parallel_widerstandsnetz_1.html", + "source": "https://50ohm.de/NEA_reihe_parallel_widerstandsnetz_1.html#ED116", "confidence": 8 }, "ED117": { - "revision": 2, - "explanation": "Capacitances in parallel add directly. Put everything in nF: $0.1\\ \\mu\\text{F} = 100$ nF, $C_2 = 150$ nF, $50000\\ \\text{pF} = 50$ nF. Sum $= 100 + 150 + 50 = 300\\ \\text{nF} = 0.3\\ \\mu\\text{F}$.", - "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "revision": 3, + "explanation": "Capacitances in parallel add directly. Put everything in nF: $0.1\\ \\mu\\text{F} = 100$ nF, $C_2 = 150$ nF, $50000\\ \\text{pF} = 50$ nF. Sum $= 100 + 150 + 50 = 300\\ \\text{nF} = 0.3\\ \\mu\\text{F}$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html#ED117", "confidence": 8 }, "ED118": { - "revision": 2, - "explanation": "Parallel capacitors add after unit conversion: $22\\ \\text{nF} + 0.033\\ \\mu\\text{F}\\,(33\\ \\text{nF}) + 15000\\ \\text{pF}\\,(15\\ \\text{nF}) = 70\\ \\text{nF} = 0.070\\ \\mu\\text{F}$. Parallel always increases total capacitance.", - "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "revision": 4, + "explanation": "Parallel capacitors add after unit conversion: $22\\ \\text{nF} + 0.033\\ \\mu\\text{F}\\,(33\\ \\text{nF}) + 15000\\ \\text{pF}\\,(15\\ \\text{nF}) = 70\\ \\text{nF} = 0.070\\ \\mu\\text{F}$. Parallel always increases total capacitance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html#ED118", "confidence": 8 }, "ED119": { - "revision": 2, - "explanation": "Capacitors in series combine like parallel resistors; for $n$ equal ones, $C_g = C/n$. Three $0.33\\ \\mu\\text{F}$ in series give $0.33/3 = 0.110\\ \\mu\\text{F}$. Series capacitance is always smaller than the smallest capacitor.", - "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "revision": 4, + "explanation": "Capacitors in series combine like parallel resistors; for $n$ equal ones, $C_g = C/n$. Three $0.33\\ \\mu\\text{F}$ in series give $0.33/3 = 0.110\\ \\mu\\text{F}$. Series capacitance is always smaller than the smallest capacitor. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html#ED119", "confidence": 8 }, "ED120": { - "revision": 2, - "explanation": "For series capacitors, $1/C_g = \\sum 1/C_i$. Convert $200000\\ \\text{nF} = 200\\ \\mu\\text{F}$, then $1/C_g = 1/100 + 1/200 + 1/200 = 2/200 + 1/200 + 1/200 = 4/200$, so $C_g = 50\\ \\mu\\text{F}$.", - "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "revision": 4, + "explanation": "For series capacitors, $1/C_g = \\sum 1/C_i$. Convert $200000\\ \\text{nF} = 200\\ \\mu\\text{F}$, then $1/C_g = 1/100 + 1/200 + 1/200 = 2/200 + 1/200 + 1/200 = 4/200$, so $C_g = 50\\ \\mu\\text{F}$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html#ED120", "confidence": 8 }, "ED121": { - "revision": 2, - "explanation": "Capacitors behave opposite to resistors for series/parallel math: parallel capacitances add, while series capacitance uses reciprocals. Two equal 10 nF capacitors in series give $10/2 = 5 nF$; in parallel with C3 = 5 nF, the total is 10 nF.", - "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "revision": 3, + "explanation": "Capacitors behave opposite to resistors for series/parallel math: parallel capacitances add, while series capacitance uses reciprocals. Two equal 10 nF capacitors in series give $10/2 = 5 nF$; in parallel with C3 = 5 nF, the total is 10 nF. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html#ED121", "confidence": 8 }, "ED122": { - "revision": 2, - "explanation": "First add the parallel capacitors: $C_2+C_3=1 uF+1 uF=2 uF$. That 2 uF equivalent is in series with C1 = 2 uF; two equal capacitors in series halve, so $C_g=1.0 uF$.", - "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "revision": 3, + "explanation": "First add the parallel capacitors: $C_2+C_3=1 uF+1 uF=2 uF$. That 2 uF equivalent is in series with C1 = 2 uF; two equal capacitors in series halve, so $C_g=1.0 uF$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html#ED122", "confidence": 8 }, "ED123": { - "revision": 2, - "explanation": "Parallel capacitors add directly, so C2 and C3 become $4 nF + 4 nF = 8 nF$. That 8 nF equivalent is in series with C1 = 8 nF, and equal series capacitors halve, giving $C_g=4 nF$.", - "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "revision": 3, + "explanation": "Parallel capacitors add directly, so C2 and C3 become $4 nF + 4 nF = 8 nF$. That 8 nF equivalent is in series with C1 = 8 nF, and equal series capacitors halve, giving $C_g=4 nF$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html#ED123", "confidence": 8 }, "ED124": { - "revision": 2, - "explanation": "Convert first so the units match: $100000 pF = 100 nF$. C2 and C3 are parallel, so they add to 200 nF; that is in series with C1 = 200 nF, and two equal series capacitances give 100 nF.", - "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "revision": 3, + "explanation": "Convert first so the units match: $100000 pF = 100 nF$. C2 and C3 are parallel, so they add to 200 nF; that is in series with C1 = 200 nF, and two equal series capacitances give 100 nF. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html#ED124", "confidence": 8 }, "ED201": { - "revision": 2, + "revision": 3, "explanation": "A Tiefpass is a low-pass filter: it lets low frequencies through and attenuates frequencies above the cutoff. On the graph that looks like high transmission on the left, then a roll-off as frequency increases.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED201", "confidence": 8 }, "ED202": { - "revision": 2, + "revision": 3, "explanation": "A Hochpass is a high-pass filter: it blocks or attenuates low frequencies and passes frequencies above the cutoff. On the graph the response starts low on the left and rises toward the right.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED202", "confidence": 8 }, "ED203": { - "revision": 2, + "revision": 3, "explanation": "A Bandpass (band-pass filter) passes only a chosen frequency range around its centre/resonant frequency. Frequencies below and above that range are attenuated, so the graph has a passband peak or plateau in the middle.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED203", "confidence": 8 }, "ED204": { - "revision": 2, + "revision": 3, "explanation": "A Bandsperre is a band-stop or notch filter: it passes frequencies below and above a selected range but rejects the middle range around resonance. The recognition cue is the dip in the response curve.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED204", "confidence": 8 }, "ED205": { - "revision": 2, + "revision": 3, "explanation": "The V-shaped impedance curve — high either side, dipping to a sharp minimum at resonance — is the signature of a series resonant circuit. At $f_0$ the inductive and capacitive reactances cancel ($X_L = X_C$), leaving only the small series resistance, so impedance is minimum.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED205", "confidence": 8 }, "ED206": { - "revision": 2, + "revision": 3, "explanation": "In a parallel resonant circuit, inductor and capacitor exchange energy while their branch currents largely cancel at resonance. The input impedance becomes maximum at $f_0=1/(2\\pi\\sqrt{LC})$, producing the peaked impedance curve.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED206", "confidence": 8 }, "ED207": { - "revision": 2, + "revision": 3, "explanation": "At resonance a parallel LC circuit (Parallelschwingkreis) presents maximum, high-ohmic impedance: the equal and opposite branch currents circulate internally and largely cancel at the terminals, drawing little current from the source. This is why a parallel tank is used as a selective load in tuned amplifiers.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED207", "confidence": 8 }, "ED208": { - "revision": 2, + "revision": 3, "explanation": "This RC network is a Tiefpass (low-pass filter). The capacitor reactance is $X_C=1/(2\\pi fC)$, so at low frequency the capacitor is nearly open and the output remains high; at high frequency it becomes a low-impedance path to ground and shunts the signal away.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED208", "confidence": 8 }, "ED209": { - "revision": 2, + "revision": 3, "explanation": "This LC network is a low-pass filter. The inductor has $X_L=2\\pi fL$, so it is easy for low frequencies and increasingly blocks high frequencies; the shunt capacitor has lower impedance at high frequency and bypasses those components to ground.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED209", "confidence": 8 }, "ED210": { - "revision": 2, + "revision": 3, "explanation": "A microphone low-pass keeps speech audio below the cutoff and removes unwanted high-frequency components. In an RC low-pass, $X_C=1/(2\\pi fC)$ falls as frequency rises, so high-frequency audio/RF components are bypassed while the wanted speech range remains at the output.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED210", "confidence": 8 }, "ED211": { - "revision": 2, + "revision": 3, "explanation": "A series capacitor followed by a load resistor is a Hochpass (high-pass filter). Because $X_C=1/(2\\pi fC)$ is large at low frequency, low-frequency components are blocked; as frequency rises the capacitor impedance falls and more signal reaches the output.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED211", "confidence": 8 }, "ED212": { - "revision": 2, + "revision": 3, "explanation": "This LC circuit is a high-pass filter. At low frequency the series capacitor has high impedance and the shunt inductor has low impedance, so low-frequency energy is blocked and bypassed; at high frequency the capacitor passes and the inductor no longer shorts the output.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED212", "confidence": 8 }, "ED213": { - "revision": 2, + "revision": 3, "explanation": "The LC ladder has the classic high-pass pattern: capacitors in the series signal path and inductors as shunt paths. Low frequencies see blocked series capacitors and easy shunt inductors; high frequencies pass through the capacitors while the inductors become high impedance.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED213", "confidence": 8 }, "ED214": { - "revision": 2, + "revision": 3, "explanation": "A Sperrkreis is a blocking or trap circuit. A parallel LC circuit has very high impedance at resonance, where $X_L=X_C$ and $f_0=1/(2\\pi\\sqrt{LC})$; placed in series with the signal path, that high impedance blocks the resonant frequency.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED214", "confidence": 8 }, "ED215": { - "revision": 2, + "revision": 3, "explanation": "A Saugkreis is a shunt notch or absorption trap. A series LC branch has minimum impedance at resonance, $f_0=1/(2\\pi\\sqrt{LC})$; connected across the signal path, it 'sucks out' that frequency by diverting it away from the output.", - "source": "https://50ohm.de/EA_schwingkreis_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED215", "confidence": 8 }, "ED216": { - "revision": 2, + "revision": 3, "explanation": "HF filters need low-loss, high-$Q$ capacitors with stable value and minimal parasitics, so ceramic (Class 1) or air-dielectric types are preferred. Electrolytics (aluminium, tantalum) are polarised, lossy, and inductive — fine for smoothing DC, useless as RF filter elements.", - "source": "https://50ohm.de/EA_kondensator_1.html", + "source": "https://50ohm.de/NEA_schwingkreis_1.html#ED216", "confidence": 8 }, "ED301": { - "revision": 2, + "revision": 3, "explanation": "A good DC supply should hold its output voltage nearly constant as the load current changes (good Spannungskonstanz / low output resistance). A radio's stages misbehave if the rail sags or carries ripple under load, so high voltage stability — not a sagging or AC-laden output — is the wanted property.", - "source": "https://50ohm.de/EA_spannungsquelle.html", + "source": "https://50ohm.de/NEA_spannungsquelle.html#ED301", "confidence": 8 }, "ED302": { - "revision": 2, + "revision": 3, "explanation": "A switch-mode supply (Schaltnetzteil) processes power by switching at tens of kHz or more, which shrinks the transformer and lets it run efficiently. The result is high efficiency, low weight, and small volume — its drawback is switching noise, not size or efficiency.", - "source": "https://50ohm.de/NEA_schaltnetzteil_1.html", + "source": "https://50ohm.de/NEA_schaltnetzteil_1.html#ED302", "confidence": 8 }, "ED303": { - "revision": 2, + "revision": 3, "explanation": "A switching power supply chops current at high frequency, creating fast edges rich in harmonics. Those components can leave through cables or radiation unless the supply has proper filtering, layout, and shielding.", - "source": "https://50ohm.de/NEA_schaltnetzteil_1.html", + "source": "https://50ohm.de/NEA_schaltnetzteil_1.html#ED303", "confidence": 8 }, "ED304": { - "revision": 2, - "explanation": "This is a single-diode half-wave rectifier. The diode conducts only on the half-cycle where it is forward biased, so current flows through the load in one direction; the opposite half-cycle is blocked, leaving pulsating DC.", - "source": "https://50ohm.de/EA_gleichrichter_1.html", + "revision": 3, + "explanation": "This is a single-diode half-wave rectifier. The diode conducts only on the half-cycle where it is forward biased, so current flows through the load in one direction; the opposite half-cycle is blocked, leaving pulsating DC. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_gleichrichter_1.html#ED304", "confidence": 8 }, "ED401": { - "revision": 2, + "revision": 3, "explanation": "Power gain means the output signal power exceeds the input signal power. Energy is conserved, so that extra power cannot come from the small input signal — it is drawn from an external DC supply, which the amplifier modulates under control of the input. No supply, no power gain.", - "source": "https://50ohm.de/NE_verstaerker.html", + "source": "https://50ohm.de/NEA_verstaerker.html#ED401", "confidence": 8 }, "ED402": { - "revision": 2, + "revision": 3, "explanation": "NF means Niederfrequenz, i.e. audio/low frequency. The shown transistor stage has the topology of a small-signal audio amplifier: it biases the transistor and couples an audio signal through capacitors, rather than using tuned RF/IF resonant circuits for frequency selection.", - "source": "https://50ohm.de/NE_verstaerker.html", + "source": "https://50ohm.de/NEA_verstaerker.html#ED402", "confidence": 8 }, "ED403": { - "revision": 2, + "revision": 3, "explanation": "An HF power amplifier (Leistungsverstärker, the PA or 'Endstufe') boosts the transmitter's already-formed RF signal up to the wanted output power before the antenna. It only raises level — modulation, mixing, and filtering happen in earlier stages.", - "source": "https://50ohm.de/NE_verstaerker.html", + "source": "https://50ohm.de/NEA_verstaerker.html#ED403", "confidence": 8 }, "ED501": { - "revision": 2, + "revision": 3, "explanation": "An LC oscillator gets its frequency from a resonant (tuned) circuit of an inductor $L$ and capacitor $C$: $f_0 = 1/(2\\pi\\sqrt{LC})$. The amplifier merely sustains the oscillation; the LC tank sets the frequency. (A crystal-controlled version would be a quartz oscillator instead.)", - "source": "https://50ohm.de/E_oszillatoren.html", + "source": "https://50ohm.de/NEA_oszillatoren.html#ED501", "confidence": 8 }, "ED502": { - "revision": 2, + "revision": 3, "explanation": "From $f_0 = 1/(2\\pi\\sqrt{LC})$, frequency falls as $C$ rises. So if warming raises the capacitor's value, the oscillator frequency drifts lower — a typical cause of thermal frequency drift in simple VFOs.", - "source": "https://50ohm.de/E_oszillatoren.html", + "source": "https://50ohm.de/NEA_oszillatoren.html#ED502", "confidence": 8 }, "ED503": { - "revision": 2, + "revision": 3, "explanation": "LC resonance follows $f_0=1/(2\\pi\\sqrt{LC})$. If capacitance $C$ is made smaller while $L$ stays the same, the denominator shrinks, so the oscillator frequency rises.", - "source": "https://50ohm.de/E_oszillatoren.html", + "source": "https://50ohm.de/NEA_oszillatoren.html#ED503", "confidence": 8 }, "ED504": { - "revision": 2, + "revision": 3, "explanation": "Same resonance law, $f_0 = 1/(2\\pi\\sqrt{LC})$: frequency falls when $L$ increases. A coil whose inductance grows with temperature therefore pulls the oscillator frequency down.", - "source": "https://50ohm.de/E_oszillatoren.html", + "source": "https://50ohm.de/NEA_oszillatoren.html#ED504", "confidence": 8 }, "ED505": { - "revision": 2, + "revision": 3, "explanation": "The oscillator frequency of an LC circuit is $f_0=1/(2\\pi\\sqrt{LC})$. Decreasing inductance $L$ makes the $LC$ product smaller, so the square-root denominator gets smaller and the frequency increases.", - "source": "https://50ohm.de/E_oszillatoren.html", + "source": "https://50ohm.de/NEA_oszillatoren.html#ED505", "confidence": 8 }, "ED506": { - "revision": 2, + "revision": 3, "explanation": "In a crystal oscillator, the quartz crystal is the frequency-determining resonator. Its mechanical resonance has very high Q and stable dimensions, so the oscillator frequency is far more stable than a simple adjustable LC circuit.", - "source": "https://50ohm.de/E_oszillatoren.html", + "source": "https://50ohm.de/NEA_oszillatoren.html#ED506", "confidence": 8 }, "ED507": { - "revision": 2, + "revision": 3, "explanation": "A quartz crystal has an extremely high $Q$ and a resonance that barely shifts with temperature or component tolerance, far more stable than an LC tank. So crystal oscillators win on frequency stability — at the cost of a very narrow tuning range, which is the trade-off the other options get backwards.", - "source": "https://50ohm.de/E_oszillatoren.html", + "source": "https://50ohm.de/NEA_oszillatoren.html#ED507", "confidence": 8 }, "EE101": { - "revision": 2, + "revision": 3, "explanation": "An unmodulated carrier is just the RF sine wave before information is added. Its amplitude, frequency, and phase stay constant, so the correct diagram is the steady, unchanged sinusoid without envelope changes or frequency variation.", - "source": "https://50ohm.de/E_unmodulierter_traeger.html", + "source": "https://50ohm.de/NEA_unmodulierter_traeger.html#EE101", "confidence": 8 }, "EE201": { - "revision": 2, + "revision": 3, "explanation": "Full AM transmits a carrier plus both sidebands; SSB removes the carrier and one sideband, sending only the information-bearing sideband. With one sideband instead of two-plus-carrier, SSB occupies less than half the bandwidth of AM — and puts all its power into useful signal.", - "source": "https://50ohm.de/E_ssb_2.html", + "source": "https://50ohm.de/NEA_ssb_2.html#EE201", "confidence": 8 }, "EE202": { - "revision": 2, + "revision": 3, "explanation": "SSB sends just one frequency-translated sideband, a copy of the audio (NF) spectrum shifted up to RF. So the occupied RF bandwidth equals the audio bandwidth — about $2.4$-$3$ kHz for speech — not double or half it.", - "source": "https://50ohm.de/E_ssb_2.html", + "source": "https://50ohm.de/NEA_ssb_2.html#EE202", "confidence": 8 }, "EE203": { - "revision": 2, - "explanation": "In upper sideband (USB), each audio component appears above the suppressed carrier by its audio frequency. A 1 kHz tone is $0.001 MHz$, so $21.250 MHz + 0.001 MHz = 21.251 MHz$.", - "source": "https://50ohm.de/E_ssb_2.html", + "revision": 4, + "explanation": "In upper sideband (USB), each audio component appears above the suppressed carrier by its audio frequency. A 1 kHz tone is $0.001 MHz$, so $21.250 MHz + 0.001 MHz = 21.251 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ssb_2.html#EE203", "confidence": 8 }, "EE204": { - "revision": 2, - "explanation": "Ideal SSB suppresses the carrier and keeps one sideband. LSB (lower sideband) places the audio below the carrier: $3.650\\ \\text{MHz} - 0.002\\ \\text{MHz} = 3.648$ MHz. Only that single component is transmitted, so options listing the carrier or upper sideband are wrong.", - "source": "https://50ohm.de/E_ssb_2.html", + "revision": 4, + "explanation": "Ideal SSB suppresses the carrier and keeps one sideband. LSB (lower sideband) places the audio below the carrier: $3.650\\ \\text{MHz} - 0.002\\ \\text{MHz} = 3.648$ MHz. Only that single component is transmitted, so options listing the carrier or upper sideband are wrong. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ssb_2.html#EE204", "confidence": 8 }, "EE205": { - "revision": 3, + "revision": 4, "explanation": "In SSB the RF output is produced directly from the audio drive — no audio, no output. Reducing the audio (NF) amplitude therefore lowers the transmitter's output power. Speaking louder or widening the audio would raise power or bandwidth, not reduce output.", - "source": "https://50ohm.de/E_slide_e_modulation.html", + "source": "https://50ohm.de/NEA_ssb_2.html#EE205", "confidence": 8 }, "EE206": { - "revision": 3, + "revision": 4, "explanation": "SSB output power tracks the audio drive into the modulator. If the microphone gain is set too low, the modulator is under-driven and the transmitter produces too little output power — the fix is more gain, up to (but not past) the point of distortion.", - "source": "https://50ohm.de/E_slide_e_modulation.html", + "source": "https://50ohm.de/NEA_ssb_2.html#EE206", "confidence": 8 }, "EE207": { - "revision": 2, + "revision": 3, "explanation": "CW (Morse) simply keys a single carrier on and off; it carries no voice spectrum, so its occupied bandwidth (a few tens of Hz, set by the keying speed) is smaller than both SSB and AM speech. That narrowness is why CW gets through when voice cannot.", - "source": "https://50ohm.de/E_ssb_2.html", + "source": "https://50ohm.de/NEA_ssb_2.html#EE207", "confidence": 8 }, "EE301": { - "revision": 2, + "revision": 3, "explanation": "Frequency modulation (FM) carries information by varying the instantaneous carrier frequency around the centre frequency. The German term Hub or Frequenzhub means frequency deviation: how far the carrier swings above and below centre. In the diagram the clue is changing wave spacing/period, not changing height.", - "source": "https://50ohm.de/EA_fm_2.html", + "source": "https://50ohm.de/NEA_fm_2.html#EE301", "confidence": 8 }, "EE302": { - "revision": 2, + "revision": 3, "explanation": "FM carries information in frequency deviation, German Hub/Frequenzhub, rather than in RF amplitude. Because the receiver can limit amplitude variations before demodulation, amplitude noise has less direct effect than it does in AM or SSB.", - "source": "https://50ohm.de/EA_fm_2.html", + "source": "https://50ohm.de/NEA_fm_2.html#EE302", "confidence": 8 }, "EE303": { - "revision": 2, + "revision": 3, "explanation": "Vehicle electrical noise often appears as unwanted amplitude spikes. FM is least affected because the wanted information is in frequency deviation, German Hub/Frequenzhub, and the receiver can limit amplitude before recovering the audio.", - "source": "https://50ohm.de/EA_fm_2.html", + "source": "https://50ohm.de/NEA_fm_2.html#EE303", "confidence": 8 }, "EE304": { - "revision": 2, + "revision": 3, "explanation": "In FM, Hub or Frequenzhub means frequency deviation: the carrier is shifted farther from its centre frequency as modulation increases. A larger deviation spreads the signal over a wider RF range, so occupied bandwidth increases.", - "source": "https://50ohm.de/EA_fm_2.html", + "source": "https://50ohm.de/NEA_fm_2.html#EE304", "confidence": 8 }, "EE305": { - "revision": 2, + "revision": 3, "explanation": "Excessive FM bandwidth is reduced by lowering the deviation setting. Deviation is the German Hub/Frequenzhub: the maximum frequency swing away from centre. Smaller Hub means the carrier moves less, so the transmitted signal occupies less bandwidth.", - "source": "https://50ohm.de/EA_fm_2.html", + "source": "https://50ohm.de/NEA_fm_2.html#EE305", "confidence": 8 }, "EE306": { - "revision": 2, + "revision": 3, "explanation": "In FM, speech loudness is represented by frequency deviation, German Hub/Frequenzhub. Louder audio pushes the instantaneous carrier farther above and below the centre frequency, while RF amplitude ideally stays constant; that is why FM receivers can use amplitude limiting.", - "source": "https://50ohm.de/EA_fm_2.html", + "source": "https://50ohm.de/NEA_fm_2.html#EE306", "confidence": 8 }, "EE401": { - "revision": 2, + "revision": 3, "explanation": "Keep the two ideas separate: bandwidth is the frequency range a signal occupies, measured in hertz; data rate is the information per time, measured in bit/s. A wide channel does not guarantee a high bit rate, and symbol rate (baud) is a third, distinct quantity.", - "source": "https://50ohm.de/NEA_datenuebertragungsdrate.html", + "source": "https://50ohm.de/NEA_datenuebertragungsdrate.html#EE401", "confidence": 8 }, "EE402": { - "revision": 2, + "revision": 3, "explanation": "Narrowband digimodes such as FT8 or BPSK31 are fed in as audio tones and sent through the rig in SSB. SSB just shifts the audio block up to RF unchanged, preserving the signal's narrow bandwidth; FM or AM would widen it and break the mode.", - "source": "https://50ohm.de/NEA_digimode_ssb.html", + "source": "https://50ohm.de/NEA_digimode_ssb.html#EE402", "confidence": 8 }, "EE403": { - "revision": 2, - "explanation": "In SSB the RF bandwidth equals the audio (NF) bandwidth, because SSB is a pure frequency translation of the audio with no extra sidebands. So a $50$ Hz audio signal occupies about $50$ Hz of RF — narrow in, narrow out.", - "source": "https://50ohm.de/NEA_digimode_ssb.html", + "revision": 3, + "explanation": "In SSB the RF bandwidth equals the audio (NF) bandwidth, because SSB is a pure frequency translation of the audio with no extra sidebands. So a $50$ Hz audio signal occupies about $50$ Hz of RF — narrow in, narrow out. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_digimode_ssb.html#EE403", "confidence": 8 }, "EE404": { - "revision": 2, + "revision": 3, "explanation": "A $2.4$ kHz SSB passband is wide enough to hold many far narrower digimode signals sitting at different audio pitches. The computer demodulates the whole passband, so depending on the mode it can decode one or several of them at once — modern FT8/PSK decoders routinely show many simultaneously.", - "source": "https://50ohm.de/NEA_digimode_ssb.html", + "source": "https://50ohm.de/NEA_digimode_ssb.html#EE404", "confidence": 8 }, "EE405": { - "revision": 3, - "explanation": "Use a reporting network: transmit with a mode designed for it (e.g. WSPR, or CW into the Reverse Beacon Network), then look up your callsign on the matching internet platform to see who copied you and where. The spots are gathered automatically by listening stations — no email handshake or made-up 'AUTO RSVP' procedure exists.", - "source": "https://50ohm.de/NEA_slide_nea_digitale_uebertragungsverfahren.html", + "revision": 4, + "explanation": "Use a reporting network: transmit with a mode designed for it (e.g. WSPR, or CW into the Reverse Beacon Network), then look up your callsign on the matching internet platform to see who copied you and where. The spots are gathered automatically by listening stations — no email handshake or made-up 'AUTO RSVP' procedure exists. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_automatische_empfangsberichte.html#EE405", "confidence": 8 }, "EE406": { - "revision": 2, + "revision": 3, "explanation": "ASK means Amplitude Shift Keying. The digital symbol is represented by changing carrier amplitude, often between a large amplitude and a small or zero amplitude, while the carrier frequency itself remains recognisably the same.", - "source": "https://50ohm.de/EA_ask_fsk_afsk.html", + "source": "https://50ohm.de/NEA_ask_fsk_afsk.html#EE406", "confidence": 8 }, "EE407": { - "revision": 2, + "revision": 3, "explanation": "FSK means Frequency Shift Keying. The digital symbol is represented by switching between carrier frequencies, so the period/wave spacing changes while the amplitude remains essentially constant.", - "source": "https://50ohm.de/EA_ask_fsk_afsk.html", + "source": "https://50ohm.de/NEA_ask_fsk_afsk.html#EE407", "confidence": 8 }, "EE408": { - "revision": 2, + "revision": 3, "explanation": "AFSK (audio frequency-shift keying) generates the FSK as an audio tone pair first, then feeds that audio into an ordinary transmitter (commonly FM) to put it on RF. The keying lives in the audio stage, which is why any SSB/FM rig with an audio input can send it — distinct from direct FSK that shifts the RF carrier itself.", - "source": "https://50ohm.de/NEA_afsk.html", + "source": "https://50ohm.de/NEA_afsk.html#EE408", "confidence": 8 }, "EE409": { - "revision": 3, + "revision": 4, "explanation": "TDMA (time-division multiple access) gives each signal its own brief time slot and lets them take rapid turns on the same frequency. They are not truly simultaneous — interleaving in time is what keeps them apart.", - "source": "https://50ohm.de/NEA_vielfachzugriff.html", + "source": "https://50ohm.de/NEA_vielfachzugriff.html#EE409", "confidence": 8 }, "EE410": { - "revision": 3, + "revision": 4, "explanation": "FDMA (frequency-division multiple access) gives each signal its own frequency channel, so all users transmit at the same time but on different frequencies. Separation is by frequency, the complement of TDMA's separation by time.", - "source": "https://50ohm.de/NEA_vielfachzugriff.html", + "source": "https://50ohm.de/NEA_vielfachzugriff.html#EE410", "confidence": 8 }, "EE411": { - "revision": 3, + "revision": 4, "explanation": "CDMA (code-division multiple access) lets all signals share the same time and frequency band; each uses a different spreading code, and the receiver correlates with the wanted code to pull its signal out of the others. Separation is by code, not time or frequency.", - "source": "https://50ohm.de/NEA_vielfachzugriff.html", + "source": "https://50ohm.de/NEA_vielfachzugriff.html#EE411", "confidence": 8 }, "EE412": { - "revision": 2, + "revision": 3, "explanation": "In a packet-switched network, two stations that cannot hear each other directly communicate by having intermediate stations relay (forward) their packets hop by hop toward the destination — the principle behind digipeaters and routed mesh networks like HAMNET.", - "source": "https://50ohm.de/NEA_paketvermittelte_netzwerke.html", + "source": "https://50ohm.de/NEA_paketvermittelte_netzwerke.html#EE412", "confidence": 8 }, "EE413": { - "revision": 2, + "revision": 3, "explanation": "The IP address together with the subnet mask defines the local subnet — the block of addresses an interface can reach directly, without going through a router. Anything outside that range must be sent via a gateway. It does not encode ports, bandwidth, or hop counts.", - "source": "https://50ohm.de/NEA_paketvermittelte_netzwerke.html", + "source": "https://50ohm.de/NEA_paketvermittelte_netzwerke.html#EE413", "confidence": 8 }, "EE414": { - "revision": 2, + "revision": 3, "explanation": "IP is a general networking protocol, not something confined to the public Internet, so it works fine over amateur links — German amateurs run it on HAMNET. The callsign is not hidden in a subnet mask, and using IP does not expose ham bands to Internet users.", - "source": "https://50ohm.de/NEA_paketvermittelte_netzwerke.html", + "source": "https://50ohm.de/NEA_paketvermittelte_netzwerke.html#EE414", "confidence": 8 }, "EE415": { - "revision": 2, + "revision": 3, "explanation": "SSTV (slow-scan TV) sends still images line by line over a narrow voice-bandwidth channel; ATV (amateur TV) sends full moving pictures and therefore needs a much wider bandwidth (only practical on UHF and up). Stills-vs-motion is the defining difference; both can be colour.", - "source": "https://50ohm.de/NEA_digimode_ssb.html", + "source": "https://50ohm.de/NEA_digimode_ssb.html#EE415", "confidence": 8 }, "EF101": { - "revision": 2, + "revision": 3, "explanation": "This is a detector receiver (crystal set style). The LC tuned circuit selects one AM station, and the diode rectifies the RF envelope so headphones can reproduce the audio; there is no local oscillator, mixer, IF stage, or active RF/audio amplification.", - "source": "https://50ohm.de/NE_detektorempf%C3%A4nger.html", + "source": "https://50ohm.de/NEA_detektorempfänger.html#EF101", "confidence": 8 }, "EF102": { - "revision": 2, + "revision": 3, "explanation": "A superheterodyne (Überlagerungsempfänger) mixes every signal down to one fixed intermediate frequency, so a single well-designed IF filter sets the selectivity for all bands. That gives far better adjacent-channel rejection (Trennschärfe) than a tuned-radio-frequency (Geradeaus) receiver, whose filters must retune with frequency.", - "source": "https://50ohm.de/E_ueberlagerungsempfaenger_einfachsuper_1.html", + "source": "https://50ohm.de/NEA_ueberlagerungsempfaenger_einfachsuper_1.html#EF102", "confidence": 8 }, "EF201": { - "revision": 2, - "explanation": "A mixer's main outputs are the sum and the absolute difference of its two input frequencies. With $31.7$ MHz and $21$ MHz: sum $= 31.7 + 21 = 52.7$ MHz and difference $= |31.7 - 21| = 10.7$ MHz. (The $10.7$ MHz difference is the classic FM IF.)", - "source": "https://50ohm.de/E_mischer.html", + "revision": 4, + "explanation": "A mixer's main outputs are the sum and the absolute difference of its two input frequencies. With $31.7$ MHz and $21$ MHz: sum $= 31.7 + 21 = 52.7$ MHz and difference $= |31.7 - 21| = 10.7$ MHz. (The $10.7$ MHz difference is the classic FM IF.) Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_mischer.html#EF201", "confidence": 8 }, "EF202": { - "revision": 2, - "explanation": "Mixing produces sum and difference: $38.7 + 28 = 66.7$ MHz and $|38.7 - 28| = 10.7$ MHz. The wanted IF is usually the difference, $10.7$ MHz, with the sum filtered out afterwards.", - "source": "https://50ohm.de/E_mischer.html", + "revision": 4, + "explanation": "Mixing produces sum and difference: $38.7 + 28 = 66.7$ MHz and $|38.7 - 28| = 10.7$ MHz. The wanted IF is usually the difference, $10.7$ MHz, with the sum filtered out afterwards. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_mischer.html#EF202", "confidence": 8 }, "EF203": { - "revision": 2, - "explanation": "The desired mixer products are the sum and difference frequencies: $30 + 39 = 69$ MHz and $|39 - 30| = 9$ MHz. The two input frequencies themselves are not the wanted output — only their sum and difference are.", - "source": "https://50ohm.de/E_mischer.html", + "revision": 4, + "explanation": "The desired mixer products are the sum and difference frequencies: $30 + 39 = 69$ MHz and $|39 - 30| = 9$ MHz. The two input frequencies themselves are not the wanted output — only their sum and difference are. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_mischer.html#EF203", "confidence": 8 }, "EF204": { - "revision": 2, - "explanation": "Sum and difference again: $145 + 136 = 281$ MHz and $|145 - 136| = 9$ MHz. So a $9$ MHz IF can be produced from these two VHF inputs, with the $281$ MHz sum rejected by the IF filter.", - "source": "https://50ohm.de/E_mischer.html", + "revision": 4, + "explanation": "Sum and difference again: $145 + 136 = 281$ MHz and $|145 - 136| = 9$ MHz. So a $9$ MHz IF can be produced from these two VHF inputs, with the $281$ MHz sum rejected by the IF filter. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_mischer.html#EF204", "confidence": 8 }, "EF205": { - "revision": 2, - "explanation": "A mixer multiplies signals, producing first-order products at the sum and absolute difference: $f_{sum}=f_1+f_2$ and $f_{diff}=|f_1-f_2|$. For 145 MHz and 136 MHz these are 281 MHz and 9 MHz.", - "source": "https://50ohm.de/E_mischer.html", + "revision": 4, + "explanation": "A mixer multiplies signals, producing first-order products at the sum and absolute difference: $f_{sum}=f_1+f_2$ and $f_{diff}=|f_1-f_2|$. For 145 MHz and 136 MHz these are 281 MHz and 9 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_mischer.html#EF205", "confidence": 8 }, "EF206": { - "revision": 2, + "revision": 3, "explanation": "A mixer deliberately creates many sum/difference products and harmonics, most of them unwanted. Good shielding (a screened enclosure) keeps those products from radiating or coupling into other stages. Loose VFO coupling or removing the earth would make leakage worse, not better.", - "source": "https://50ohm.de/E_mischer.html", + "source": "https://50ohm.de/NEA_mischer.html#EF206", "confidence": 8 }, "EF207": { - "revision": 2, + "revision": 3, "explanation": "An oscillator radiates RF that could leak out as a spurious emission or reach other stages, so it belongs inside a grounded metal screen (Abschirmung). Shielding plus good supply decoupling contains its energy; leaving it unshielded or unfiltered does the opposite.", - "source": "https://50ohm.de/NE_oszillatoren.html", + "source": "https://50ohm.de/NEA_oszillatoren.html#EF207", "confidence": 8 }, "EF208": { - "revision": 2, + "revision": 3, "explanation": "A direct-conversion (Direktüberlagerung) receiver mixes straight down to audio, i.e. an IF of essentially zero. For the difference frequency to land at audio, the local oscillator must sit right next to the received frequency — only a few kHz away.", - "source": "https://50ohm.de/E_ueberlagerungsempfaenger_einfachsuper_1.html", + "source": "https://50ohm.de/NEA_ueberlagerungsempfaenger_einfachsuper_1.html#EF208", "confidence": 8 }, "EF209": { - "revision": 2, + "revision": 3, "explanation": "A BFO is a beat frequency oscillator. CW and SSB do not arrive as ordinary AM audio by themselves; the BFO supplies a local carrier so the detector can mix it with the received signal and produce an audible beat or speech audio.", - "source": "https://50ohm.de/NEA_bfo_1.html", + "source": "https://50ohm.de/NEA_bfo_1.html#EF209", "confidence": 8 }, "EF210": { - "revision": 2, + "revision": 3, "explanation": "Selectivity is a receiver's ability to accept the wanted frequency while rejecting nearby signals. A narrower IF/audio bandwidth passes less adjacent-channel energy, so high selectivity means nearby stations interfere less.", - "source": "https://50ohm.de/E_trennschaerfe_1.html", + "source": "https://50ohm.de/NEA_trennschaerfe_1.html#EF210", "confidence": 8 }, "EF211": { - "revision": 2, + "revision": 3, "explanation": "AGC means Automatic Gain Control. It reduces receiver gain when strong signals arrive and increases gain again for weak signals, keeping the demodulated audio level more constant and preventing overload.", - "source": "https://50ohm.de/NE_agc_1.html", + "source": "https://50ohm.de/NEA_agc_1.html#EF211", "confidence": 8 }, "EF212": { - "revision": 2, + "revision": 3, "explanation": "AGC stands for Automatic Gain Control. It is a feedback system in the receiver that automatically changes gain according to signal strength, reducing large audio level swings between weak and strong stations.", - "source": "https://50ohm.de/NE_agc_1.html", + "source": "https://50ohm.de/NEA_agc_1.html#EF212", "confidence": 8 }, "EF213": { - "revision": 2, + "revision": 3, "explanation": "Receiver noise reduction tries to tell wanted signal from random noise and suppress the noise part of the received audio, improving readability. It works on the demodulated signal content, not on the power supply or the IF dynamic range.", - "source": "https://50ohm.de/NE_noise_reduction.html", + "source": "https://50ohm.de/NEA_noise_reduction.html#EF213", "confidence": 8 }, "EF214": { - "revision": 2, + "revision": 3, "explanation": "A noise blanker is designed for short impulsive noise, such as ignition clicks. It detects the pulse and briefly gates or blanks the receiver path, whereas a notch filter removes one narrow tone and AGC only changes gain.", - "source": "https://50ohm.de/NE_noise_reduction.html", + "source": "https://50ohm.de/NEA_noise_reduction.html#EF214", "confidence": 8 }, "EF215": { - "revision": 2, + "revision": 3, "explanation": "A notch filter is a very narrow band-stop: it rejects one small slice of frequency (e.g. an interfering carrier or heterodyne whistle) while passing everything else. Low-, high-, and band-pass filters all pass a broad range instead, so they cannot remove a single narrow tone cleanly.", - "source": "https://50ohm.de/NE_notchfilter.html", + "source": "https://50ohm.de/NEA_notchfilter.html#EF215", "confidence": 8 }, "EF216": { - "revision": 2, + "revision": 3, "explanation": "A notch filter is a very narrow band-stop filter. The response should pass most nearby frequencies but have one sharp rejection dip at the interfering tone, so the correct diagram is the otherwise flat passband with a narrow notch.", - "source": "https://50ohm.de/NE_notchfilter.html", + "source": "https://50ohm.de/NEA_notchfilter.html#EF216", "confidence": 8 }, "EF217": { - "revision": 2, + "revision": 3, "explanation": "An attenuator is a deliberate RF loss inserted before the receiver front end. It lowers all incoming signals, which can improve real reception when strong local signals would otherwise overload the mixer or RF amplifier.", - "source": "https://50ohm.de/NE_vorverstaerker_daempfungsglied.html", + "source": "https://50ohm.de/NEA_vorverstaerker_daempfungsglied.html#EF217", "confidence": 8 }, "EF218": { - "revision": 2, + "revision": 3, "explanation": "Put a UHF preamplifier right at the antenna. Amplifying the weak signal before it suffers feed-line loss sets a low overall noise figure (Friis): loss ahead of the first amplifier adds directly to the noise figure, so preamplifying after the cable would be far worse.", - "source": "https://50ohm.de/NE_vorverstaerker_daempfungsglied.html", + "source": "https://50ohm.de/NEA_vorverstaerker_daempfungsglied.html#EF218", "confidence": 8 }, "EF219": { - "revision": 2, + "revision": 3, "explanation": "9600-baud packet/FM data needs the discriminator or demodulator signal before speech audio shaping filters distort it. Therefore the receive 9600-port is taken directly after the FM demodulator, at point 4 in the shown chain.", - "source": "https://50ohm.de/NEA_9600_port.html", + "source": "https://50ohm.de/NEA_9600_port.html#EF219", "confidence": 8 }, "EF301": { - "revision": 2, - "explanation": "A frequency multiplier chain multiplies stage by stage, so to find the oscillator frequency you work backward by dividing by each multiplier. Here $145.2 MHz / 2 / 3 / 2 = 12.1 MHz$.", - "source": "https://50ohm.de/NE_frequenzvervielfacher_1.html", + "revision": 4, + "explanation": "A frequency multiplier chain multiplies stage by stage, so to find the oscillator frequency you work backward by dividing by each multiplier. Here $145.2 MHz / 2 / 3 / 2 = 12.1 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzvervielfacher_1.html#EF301", "confidence": 8 }, "EF302": { - "revision": 2, - "explanation": "Frequency multipliers scale the input frequency by their factor. To recover the starting oscillator frequency, reverse the chain by division: $21.360 MHz / 3 / 2 = 3.560 MHz$.", - "source": "https://50ohm.de/NE_frequenzvervielfacher_1.html", + "revision": 4, + "explanation": "Frequency multipliers scale the input frequency by their factor. To recover the starting oscillator frequency, reverse the chain by division: $21.360 MHz / 3 / 2 = 3.560 MHz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzvervielfacher_1.html#EF302", "confidence": 8 }, "EF303": { - "revision": 2, - "explanation": "Trace the multiplier chain: the VFO at $3.51$ MHz passes two doublers, $\\times 2 \\times 2 = \\times 4$, giving $3.51 \\cdot 4 = 14.04$ MHz at output a. Frequency multipliers move a low, stable VFO up to the wanted band.", - "source": "https://50ohm.de/NE_frequenzvervielfacher_1.html", + "revision": 4, + "explanation": "Trace the multiplier chain: the VFO at $3.51$ MHz passes two doublers, $\\times 2 \\times 2 = \\times 4$, giving $3.51 \\cdot 4 = 14.04$ MHz at output a. Frequency multipliers move a low, stable VFO up to the wanted band. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzvervielfacher_1.html#EF303", "confidence": 8 }, "EF304": { - "revision": 2, + "revision": 3, "explanation": "A VFO's frequency is set by its $L$ and $C$, whose values drift slowly as temperature changes. The result is a slow frequency drift (not amplitude jumps) — which is why stable oscillators use temperature compensation or are locked to a reference.", - "source": "https://50ohm.de/NE_oszillatoren.html", + "source": "https://50ohm.de/NEA_oszillatoren.html#EF304", "confidence": 8 }, "EF305": { - "revision": 2, + "revision": 3, "explanation": "ALC (automatic level control) guards the transmit chain: when the audio (NF) drive is too strong, it reduces the signal amplitude ahead of the power amplifier to prevent overdrive, distortion, and splatter. It acts in the transmit path, not on the receiver gain.", - "source": "https://50ohm.de/NEA_alc.html", + "source": "https://50ohm.de/NEA_alc.html#EF305", "confidence": 8 }, "EF306": { - "revision": 3, + "revision": 4, "explanation": "A dynamic compressor reduces speech dynamic range: loud syllables are limited or reduced, while quiet syllables are brought up relative to them. In radio this can raise average talk power without increasing peaks as much.", - "source": "https://50ohm.de/NE_slide_ne_modulation.html", + "source": "https://50ohm.de/NEA_dynamik_kompressor_1.html#EF306", "confidence": 8 }, "EF307": { - "revision": 2, + "revision": 3, "explanation": "A speech microphone amplifier is an audio band-pass stage: it should pass the intelligible voice range, roughly 300 Hz to 3 kHz, while rejecting rumble below it and hiss/RF products above it. That corresponds to the band-pass graph.", - "source": "https://50ohm.de/NE_verstaerker.html", + "source": "https://50ohm.de/NEA_verstaerker.html#EF307", "confidence": 8 }, "EF308": { - "revision": 2, - "explanation": "Speech intelligibility needs roughly the $300$ Hz-$2.7$ kHz band, so an audio amplifier for SSB voice needs at least about $2.5$ kHz of bandwidth. More than that wastes bandwidth; much less (1 kHz) would make speech hard to understand.", - "source": "https://50ohm.de/NE_verstaerker.html", + "revision": 4, + "explanation": "Speech intelligibility needs roughly the $300$ Hz-$2.7$ kHz band, so an audio amplifier for SSB voice needs at least about $2.5$ kHz of bandwidth. More than that wastes bandwidth; much less (1 kHz) would make speech hard to understand. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_verstaerker.html#EF308", "confidence": 8 }, "EF309": { - "revision": 2, + "revision": 3, "explanation": "For 9600-baud FM data, normal microphone filtering and pre-emphasis would distort the baseband waveform. The data signal therefore enters directly at the FM modulator input, point 2 in the transmitter diagram.", - "source": "https://50ohm.de/NEA_9600_port.html", + "source": "https://50ohm.de/NEA_9600_port.html#EF309", "confidence": 8 }, "EF310": { - "revision": 2, - "explanation": "An SSB voice signal only needs the width of one speech sideband, so the sideband-selecting filter is about $2.4$ kHz wide. The other values are unrelated ($455$ kHz and $10.7$ MHz are IF centre frequencies, not bandwidths; $800$ Hz is too narrow for voice).", - "source": "https://50ohm.de/E_ssb_2.html", + "revision": 4, + "explanation": "An SSB voice signal only needs the width of one speech sideband, so the sideband-selecting filter is about $2.4$ kHz wide. The other values are unrelated ($455$ kHz and $10.7$ MHz are IF centre frequencies, not bandwidths; $800$ Hz is too narrow for voice). Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ssb_2.html#EF310", "confidence": 8 }, "EF401": { - "revision": 2, + "revision": 3, "explanation": "Transmitter output power is the power measured right at the transmitter output, before any tuner, filter, or feed line alters it. It is not a forward-minus-reflected figure or a near-field antenna measurement — just the raw power leaving the rig.", - "source": "https://50ohm.de/E_senderausgangsleistung.html", + "source": "https://50ohm.de/NEA_senderausgangsleistung.html#EF401", "confidence": 8 }, "EF402": { - "revision": 2, + "revision": 3, "explanation": "SSB PEP (peak envelope power) is measured directly at the transmitter output while it is driven with a steady one- or two-tone test signal, which produces a constant envelope peak you can read. An unmodulated carrier gives no SSB output (no audio, no signal), so it cannot be used.", - "source": "https://50ohm.de/E_senderausgangsleistung.html", + "source": "https://50ohm.de/NEA_senderausgangsleistung.html#EF402", "confidence": 8 }, "EF403": { - "revision": 2, + "revision": 3, "explanation": "An SSB signal carries its information in amplitude and phase variations, so the final stage must be a linear amplifier (Klasse A/AB) to reproduce the envelope faithfully. A limiter or non-linear stage would distort the envelope and splatter into neighbouring channels; a multiplier would destroy the signal entirely.", - "source": "https://50ohm.de/EA_verstaerker.html", + "source": "https://50ohm.de/NEA_verstaerker.html#EF403", "confidence": 8 }, "EF404": { - "revision": 2, + "revision": 3, "explanation": "Re-adjusting the final amplifier's operating point (bias) changes its linearity and can create new harmonics, so the transmitter must be re-checked for harmonic emissions afterwards. Checking only when interference is heard would be too late — verify after any change to the PA.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EF404", "confidence": 8 }, "EF405": { - "revision": 2, + "revision": 3, "explanation": "The transmitter's DC supply leads should be well decoupled against RF (chokes and bypass capacitors), so stray RF cannot ride back onto the power wiring or feed between stages and cause instability or interference. Making the supply high-impedance or low-capacitance to ground would worsen, not improve, RF behaviour.", - "source": "https://50ohm.de/EA_verstaerker.html", + "source": "https://50ohm.de/NEA_verstaerker.html#EF405", "confidence": 8 }, "EF501": { - "revision": 2, + "revision": 3, "explanation": "A transverter shifts a band in both directions: on receive it converts the higher band (e.g. $70$ cm) down into the transceiver's band ($10$ m), and on transmit it converts the $10$ m signal back up to $70$ cm. It only moves frequency — it does not change the modulation type or digital protocol.", - "source": "https://50ohm.de/NE_transverter_1.html", + "source": "https://50ohm.de/NEA_transverter_1.html#EF501", "confidence": 8 }, "EF502": { - "revision": 2, + "revision": 3, "explanation": "A transverter changes band by mixing: it beats the signal against a local oscillator and keeps the wanted sum or difference product. Multiplication, division, or feedback would not translate a whole modulated band intact the way heterodyne mixing does.", - "source": "https://50ohm.de/NE_transverter_1.html", + "source": "https://50ohm.de/NEA_transverter_1.html#EF502", "confidence": 8 }, "EF503": { - "revision": 2, + "revision": 3, "explanation": "A transverter performs bidirectional frequency conversion around an existing transceiver: on receive it downconverts the target band, and on transmit it upconverts the transceiver output. The shown receive/transmit conversion around a VHF transceiver identifies it as a 2 m transverter setup.", - "source": "https://50ohm.de/NE_transverter_1.html", + "source": "https://50ohm.de/NEA_transverter_1.html#EF503", "confidence": 8 }, "EF504": { - "revision": 2, + "revision": 3, "explanation": "The diagram shows only transmit upconversion: a VHF signal is mixed with a local oscillator and filtered to produce a signal in the 13 cm band. That makes it a transmit converter for 13 cm, not a complete bidirectional transverter.", - "source": "https://50ohm.de/NE_transverter_1.html", + "source": "https://50ohm.de/NEA_transverter_1.html#EF504", "confidence": 8 }, "EF505": { - "revision": 2, + "revision": 3, "explanation": "For a $2.4$ GHz uplink the local oscillator is multiplied up to the transmit frequency, and multiplication scales any oscillator error by the same factor. A small drift at the XO becomes a large drift at GHz — easily more than SSB's few-hundred-Hz tolerance — so the LO must be temperature-stabilised or locked to a high-grade reference.", - "source": "https://50ohm.de/NE_transverter_1.html", + "source": "https://50ohm.de/NEA_transverter_1.html#EF505", "confidence": 8 }, "EF601": { - "revision": 2, + "revision": 3, "explanation": "In a DSP chain the analogue input must first be sampled by an A/D converter (block 1, ADC) so the maths can run on numbers; after processing, a D/A converter (block 2, DAC) rebuilds an analogue output. The order is fixed by the signal flow: digitise, process, reconstruct.", - "source": "https://50ohm.de/NEA_digitale_signalverarbeitung_einleitung.html", + "source": "https://50ohm.de/NEA_digitale_signalverarbeitung_einleitung.html#EF601", "confidence": 8 }, "EF602": { - "revision": 2, + "revision": 3, "explanation": "A digital filter operates on numerical samples, not on a continuous waveform, so the analogue input must first be digitised (A/D conversion) before it can be filtered. Demodulation or noise/harmonic removal are not prerequisites — sampling is.", - "source": "https://50ohm.de/NEA_digitale_signalverarbeitung_einleitung.html", + "source": "https://50ohm.de/NEA_digitale_signalverarbeitung_einleitung.html#EF602", "confidence": 8 }, "EF603": { - "revision": 2, + "revision": 3, "explanation": "SDR means Software-Defined Radio: at least part of the signal processing (filtering, demodulation, often the whole IF chain) is done in software rather than fixed hardware. It is still radio over the air, just with the heavy lifting moved into code.", - "source": "https://50ohm.de/NEA_digitale_signalverarbeitung_einleitung.html", + "source": "https://50ohm.de/NEA_digitale_signalverarbeitung_einleitung.html#EF603", "confidence": 8 }, "EG101": { - "revision": 2, + "revision": 3, "explanation": "A loop built from three equal wire sections forms a triangle, i.e. a delta loop (Delta-Loop) — a full-wave loop bent into three sides. A quad loop is four-sided, a W3DZZ is a trap dipole, and a beam is a multi-element directional array, so none of those match a three-sided loop.", - "source": "https://50ohm.de/EA_antennenformen_2.html", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG101", "confidence": 8 }, "EG102": { - "revision": 2, - "explanation": "A wire HF antenna can in principle be any length: with a suitable matching network (Antennentuner) you can present $50\\ \\Omega$ to the transmitter even when the wire is not resonant. The wire's length sets its resonance and feed-point impedance, not whether it can be used at all — so the rigid $\\lambda/2$ or $\\lambda/4$ options are wrong.", - "source": "https://50ohm.de/NE_antenne_laenge_resonanz.html", + "revision": 3, + "explanation": "A wire HF antenna can in principle be any length: with a suitable matching network (Antennentuner) you can present $50\\ \\Omega$ to the transmitter even when the wire is not resonant. The wire's length sets its resonance and feed-point impedance, not whether it can be used at all — so the rigid $\\lambda/2$ or $\\lambda/4$ options are wrong. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_antenne_laenge_resonanz.html#EG102", "confidence": 8 }, "EG103": { - "revision": 2, + "revision": 3, "explanation": "The diagram shows an end-fed antenna: the wire is fed at one end rather than in the middle. Because an end-fed half-wave wire has high feed impedance, it needs a matching unit to transform that impedance toward the transmitter/feed-line impedance.", - "source": "https://50ohm.de/E_antennenformen_2.html", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG103", "confidence": 8 }, "EG104": { - "revision": 2, + "revision": 3, "explanation": "A Fuchs antenna is a form of end-fed half-wave antenna using a tuned matching circuit, often a parallel resonant circuit, at the feed end. The tuned circuit transforms the high end impedance so the transmitter can feed the wire efficiently.", - "source": "https://50ohm.de/E_antennenformen_2.html", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG104", "confidence": 8 }, "EG105": { - "revision": 2, - "explanation": "A magnetic loop is electrically small, often around $\\lambda/10$ circumference or less. Its current is high and voltage is comparatively low, so the near field is dominated by the magnetic H-field; this is why it behaves differently from a full-size resonant wire antenna.", - "source": "https://50ohm.de/EA_antennenformen_2.html", + "revision": 3, + "explanation": "A magnetic loop is electrically small, often around $\\lambda/10$ circumference or less. Its current is high and voltage is comparatively low, so the near field is dominated by the magnetic H-field; this is why it behaves differently from a full-size resonant wire antenna. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG105", "confidence": 8 }, "EG106": { - "revision": 2, + "revision": 3, "explanation": "Typical HF (Kurzwelle) transmitting antennas are wire/boom types: long wire, Yagi-Uda, dipole, Windom, and delta loop. Horn, patch, slot, and parabolic dish antennas need dimensions of several wavelengths, which is only practical at VHF/UHF and microwave — so any answer list containing them is wrong for HF.", - "source": "https://50ohm.de/EA_antennenformen_2.html", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG106", "confidence": 8 }, "EG107": { - "revision": 3, + "revision": 4, "explanation": "For the 80 m band ($\\lambda \\approx 80$ m) you need physically large wire antennas: a dipole, a delta loop, and the W3DZZ (a trap dipole for multiband HF) all fit. A parabolic dish or cross-Yagi would be enormous at 80 m, and a sleeve/Sperrtopf antenna is a VHF/UHF form, so the lists containing those are out.", - "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG107", "confidence": 8 }, "EG108": { - "revision": 2, - "explanation": "A $5/8\\,\\lambda$ vertical concentrates more of its radiation toward the horizon than a $\\lambda/4$ whip, giving roughly 1-3 dB more gain in useful low-angle directions — ideal for mobile VHF/UHF where you want range along the ground. The other options (power handling, mounting, noise) are not the reason it is preferred.", - "source": "https://50ohm.de/E_antennenformen_2.html", + "revision": 3, + "explanation": "A $5/8\\,\\lambda$ vertical concentrates more of its radiation toward the horizon than a $\\lambda/4$ whip, giving roughly 1-3 dB more gain in useful low-angle directions — ideal for mobile VHF/UHF where you want range along the ground. The other options (power handling, mounting, noise) are not the reason it is preferred. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG108", "confidence": 8 }, "EG109": { - "revision": 2, - "explanation": "First the wavelength: $\\lambda = 300 / f_{\\text{MHz}} = 300/28.5 \\approx 10.53$ m. The electrical length of a $5/8\\,\\lambda$ radiator is $0.625 \\cdot 10.53 \\approx 6.58$ m. (This is the electrical length; a real whip is trimmed a few percent shorter for the velocity factor.)", - "source": "https://50ohm.de/NE_antenne_laenge_resonanz.html", + "revision": 3, + "explanation": "First the wavelength: $\\lambda = 300 / f_{\\text{MHz}} = 300/28.5 \\approx 10.53$ m. The electrical length of a $5/8\\,\\lambda$ radiator is $0.625 \\cdot 10.53 \\approx 6.58$ m. (This is the electrical length; a real whip is trimmed a few percent shorter for the velocity factor.) Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_antenne_laenge_resonanz.html#EG109", "confidence": 8 }, "EG110": { - "revision": 2, + "revision": 3, "explanation": "A folded dipole (Faltdipol) is a half-wave dipole whose two parallel conductors are joined at the ends, forming a thin loop. Going out along the top and back along the bottom totals two half-waves, so the wire used is one full wavelength ($\\lambda$).", - "source": "https://50ohm.de/NE_antenne_laenge_resonanz.html", + "source": "https://50ohm.de/NEA_antenne_laenge_resonanz.html#EG110", "confidence": 8 }, "EG111": { - "revision": 2, + "revision": 3, "explanation": "In a Yagi-Uda antenna, only the driven element is fed directly. The reflector is slightly longer and sits behind it; the director is slightly shorter and sits in front, so the order along the boom is reflector, driven element, director.", - "source": "https://50ohm.de/NE_yagi_uda_2.html", + "source": "https://50ohm.de/NEA_yagi_uda_2.html#EG111", "confidence": 8 }, "EG112": { - "revision": 3, + "revision": 4, "explanation": "Coupling into a neighbour's equipment grows with the field strength reaching it, which falls with distance and with how much the main beam misses their house. Mounting the directional antenna as high and as far away as possible therefore minimises the field at the neighbour — the opposite of placing it low, close, or aimed over their roof.", - "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_standortwahl.html#EG112", "confidence": 8 }, "EG113": { - "revision": 2, + "revision": 3, "explanation": "A sharply focused microwave antenna is usually a parabolic dish: a paraboloid reflector (Spiegel) plus a small feed antenna (Erreger/Feed) at its focus. The feed illuminates the dish, which reflects the energy into a narrow parallel beam. An isotropic radiator is only a theoretical reference, not a real feed.", - "source": "https://50ohm.de/EA_parabolspiegel_1.html", + "source": "https://50ohm.de/NEA_parabolspiegel_1.html#EG113", "confidence": 8 }, "EG114": { - "revision": 2, + "revision": 3, "explanation": "Dish gain rises with aperture measured in wavelengths — bigger relative to $\\lambda$ means a narrower beam and more gain. A reflector of at least about five wavelengths diameter is the practical minimum for high gain; one or two wavelengths is too small to form a tight beam.", - "source": "https://50ohm.de/EA_parabolspiegel_1.html", + "source": "https://50ohm.de/NEA_parabolspiegel_1.html#EG114", "confidence": 8 }, "EG201": { - "revision": 2, + "revision": 3, "explanation": "The velocity factor (Verkürzungsfaktor) is the ratio of wave propagation speed on the line or wire to its speed in vacuum, always $< 1$. Because the wave travels slower, a resonant element is physically shorter than the free-space $\\lambda/2$ — hence the name shortening factor.", - "source": "https://50ohm.de/E_verkuerzungsfaktor_1.html", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_1.html#EG201", "confidence": 8 }, "EG202": { - "revision": 2, + "revision": 3, "explanation": "A real wire antenna is electrically a little longer than its physical length because of end effects and the wave speed near the conductor. The usual shortening factor is about 0.95, so physical length is roughly $0.95 \\cdot \\lambda/2$ for a half-wave wire.", - "source": "https://50ohm.de/E_verkuerzungsfaktor_1.html", + "source": "https://50ohm.de/NEA_verkuerzungsfaktor_1.html#EG202", "confidence": 8 }, "EG203": { - "revision": 2, + "revision": 3, "explanation": "A dipole's ends are open circuits: charge piles up there, so voltage is maximum (voltage antinode, Spannungsbauch) while the current must fall to zero (current node, Stromknoten). Current can only be large where it has somewhere to flow, i.e. toward the centre, not at the open tips.", - "source": "https://50ohm.de/NEA_strom_spannung_speisung_1.html", + "source": "https://50ohm.de/NEA_strom_spannung_speisung_1.html#EG203", "confidence": 8 }, "EG204": { - "revision": 2, + "revision": 3, "explanation": "Current feeding (Stromspeisung) means the feed point sits at a current antinode (Strombauch) and a voltage node (Spannungsknoten). With high current and low voltage there, the impedance $Z = U/I$ is low — a centre-fed half-wave dipole is the classic example at about $50$-$75\\ \\Omega$.", - "source": "https://50ohm.de/NE_strom_spannung_speisung_1.html", + "source": "https://50ohm.de/NEA_strom_spannung_speisung_1.html#EG204", "confidence": 8 }, "EG205": { - "revision": 2, + "revision": 3, "explanation": "Voltage feeding (Spannungsspeisung) is the opposite of current feeding: the feed point is a voltage antinode (Spannungsbauch) and a current node (Stromknoten). High voltage with near-zero current makes $Z = U/I$ very high — e.g. feeding a half-wave element at its end.", - "source": "https://50ohm.de/NE_strom_spannung_speisung_1.html", + "source": "https://50ohm.de/NEA_strom_spannung_speisung_1.html#EG205", "confidence": 8 }, "EG206": { - "revision": 2, + "revision": 3, "explanation": "On its fundamental a half-wave dipole carries a half-sine current distribution: maximum in the middle, zero at the ends. Feeding it at the centre therefore taps a current antinode (Strombauch), which is by definition current feeding (low impedance).", - "source": "https://50ohm.de/NE_strom_spannung_speisung_1.html", + "source": "https://50ohm.de/NEA_strom_spannung_speisung_1.html#EG206", "confidence": 8 }, "EG207": { - "revision": 2, + "revision": 3, "explanation": "A center-fed half-wave dipole in free space has a feed-point resistance of about $73\\ \\Omega$; raised at least a wavelength above ground it stays near that value, which the exam rounds to $75\\ \\Omega$. That is also why $75\\ \\Omega$ coax is a natural match for a simple dipole.", - "source": "https://50ohm.de/E_fusspunktimpedanz_1.html", + "source": "https://50ohm.de/NEA_fusspunktimpedanz_1.html#EG207", "confidence": 8 }, "EG208": { - "revision": 2, + "revision": 3, "explanation": "The free-space figure ($\\approx 73\\ \\Omega$) shifts when the dipole is near ground: reflections add in or out of phase depending on height, so the feed resistance swings over roughly $40$-$90\\ \\Omega$ at practical heights. That spread is why a dipole still works acceptably on either $50$ or $75\\ \\Omega$ coax.", - "source": "https://50ohm.de/E_fusspunktimpedanz_1.html", + "source": "https://50ohm.de/NEA_fusspunktimpedanz_1.html#EG208", "confidence": 8 }, "EG209": { - "revision": 2, + "revision": 3, "explanation": "A straight, center-fed half-wave dipole has the same height-dependent feed resistance as above: about $40$-$90\\ \\Omega$ over realistic installation heights, centred on the free-space $\\approx 73\\ \\Omega$. The wider answers (240-300 $\\Omega$) belong to a folded dipole, not a plain one.", - "source": "https://50ohm.de/E_fusspunktimpedanz_1.html", + "source": "https://50ohm.de/NEA_fusspunktimpedanz_1.html#EG209", "confidence": 8 }, "EG210": { - "revision": 2, + "revision": 3, "explanation": "A folded dipole (Faltdipol) splits the antenna current between its two parallel conductors. Halving the current at the same power raises the feed-point resistance by a factor of about four ($2^2$), turning the dipole's $\\approx 70\\ \\Omega$ into roughly $240$-$300\\ \\Omega$ — the classic match for $300\\ \\Omega$ ribbon feeder.", - "source": "https://50ohm.de/E_fusspunktimpedanz_1.html", + "source": "https://50ohm.de/NEA_fusspunktimpedanz_1.html#EG210", "confidence": 8 }, "EG211": { - "revision": 3, + "revision": 4, "explanation": "A quarter-wave ground-plane (Groundplane) works against its radials rather than a second arm. With horizontal radials the feed resistance is near $35\\ \\Omega$; drooping the radials downward raises it toward $50\\ \\Omega$, so the practical range is about $30$-$50\\ \\Omega$ — a good direct match to $50\\ \\Omega$ coax.", - "source": "https://50ohm.de/E_fusspunktimpedanz_1.html", + "source": "https://50ohm.de/NEA_fusspunktimpedanz_1.html#EG211", "confidence": 8 }, "EG212": { - "revision": 2, + "revision": 3, "explanation": "In a Yagi-Uda only one element is actually fed — the driven element (Strahler). The reflector and directors are parasitic: they carry current induced by the driven element and reshape the pattern, but no feeder connects to them.", - "source": "https://50ohm.de/NE_yagi_uda_2.html", + "source": "https://50ohm.de/NEA_yagi_uda_2.html#EG212", "confidence": 8 }, "EG213": { - "revision": 2, - "explanation": "A ground-plane is unbalanced (asymmetric): one side is the radiator, the other is the radial/counterpoise system near earth potential, so the two halves are not mirror images. A folded dipole, a long Yagi, and a center-fed $\\lambda/2$ dipole are all symmetric about their feed point.", - "source": "https://50ohm.de/EA_antennenformen_2.html", + "revision": 3, + "explanation": "A ground-plane is unbalanced (asymmetric): one side is the radiator, the other is the radial/counterpoise system near earth potential, so the two halves are not mirror images. A folded dipole, a long Yagi, and a center-fed $\\lambda/2$ dipole are all symmetric about their feed point. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG213", "confidence": 8 }, "EG214": { - "revision": 2, + "revision": 3, "explanation": "A half-wave dipole radiates broadside: strongest at right angles to the wire and weakest off the wire ends. From above this gives two equal lobes, so the symmetric two-lobed diagram is the dipole pattern.", - "source": "https://50ohm.de/NE_antennenformen_2.html", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG214", "confidence": 8 }, "EG215": { - "revision": 2, + "revision": 3, "explanation": "The clue is maximum radiation perpendicular to the conductor and nulls toward the conductor ends. That is the horizontal pattern of a half-wave dipole, often drawn as a figure-eight from above.", - "source": "https://50ohm.de/NE_antennenformen_2.html", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG215", "confidence": 8 }, "EG216": { - "revision": 2, + "revision": 3, "explanation": "A vertical ground-plane antenna radiates roughly equally in all horizontal directions, so its top-view azimuth pattern is nearly circular. Its useful directivity is mainly in elevation, not around the compass.", - "source": "https://50ohm.de/EA_antennenformen_2.html", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG216", "confidence": 8 }, "EG217": { - "revision": 2, + "revision": 3, "explanation": "A directional antenna concentrates radiation into a main lobe instead of radiating equally in all directions. The large forward lobe, with smaller rear or side lobes, is the visual cue for directional gain.", - "source": "https://50ohm.de/EA_antennenformen_2.html", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG217", "confidence": 8 }, "EG218": { - "revision": 2, + "revision": 3, "explanation": "A Yagi-Uda antenna uses parasitic reflector/director elements to reinforce radiation in one direction. Its pattern therefore has a strong main lobe toward the directors and much smaller rear/side lobes.", - "source": "https://50ohm.de/NE_yagi_uda_2.html", + "source": "https://50ohm.de/NEA_yagi_uda_2.html#EG218", "confidence": 8 }, "EG219": { - "revision": 2, - "explanation": "A vertical half-wave antenna radiates mainly perpendicular to the vertical conductor. Since the conductor is vertical, the strongest radiation leaves at low elevation angles, which is useful for DX because low-angle rays make longer ionospheric hops.", - "source": "https://50ohm.de/E_antennenformen_2.html", + "revision": 3, + "explanation": "A vertical half-wave antenna radiates mainly perpendicular to the vertical conductor. Since the conductor is vertical, the strongest radiation leaves at low elevation angles, which is useful for DX because low-angle rays make longer ionospheric hops. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_antennenformen_2.html#EG219", "confidence": 8 }, "EG220": { - "revision": 2, + "revision": 3, "explanation": "The suffix dBi means gain in decibels relative to an isotropic radiator (Isotropstrahler) — the ideal point source that radiates equally in every direction. It is a pure reference: no real antenna is isotropic, but it gives an absolute baseline for comparing gains.", - "source": "https://50ohm.de/NE_antennengewinn.html", + "source": "https://50ohm.de/NEA_antennengewinn.html#EG220", "confidence": 8 }, "EG221": { - "revision": 2, - "explanation": "dBd is referenced to a half-wave dipole, and a dipole already has $2.15$ dBi of gain over isotropic. So convert by adding that offset: $5\\ \\text{dBd} + 2.15\\ \\text{dB} = 7.15$ dBi. Whenever you see dBi vs dBd, the gap is always $2.15$ dB.", - "source": "https://50ohm.de/NE_antennengewinn.html", + "revision": 4, + "explanation": "dBd is referenced to a half-wave dipole, and a dipole already has $2.15$ dBi of gain over isotropic. So convert by adding that offset: $5\\ \\text{dBd} + 2.15\\ \\text{dB} = 7.15$ dBi. Whenever you see dBi vs dBd, the gap is always $2.15$ dB. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_antennengewinn.html#EG221", "confidence": 8 }, "EG222": { - "revision": 2, + "revision": 3, "explanation": "Polarisation is defined by the orientation of the electric field component in the main beam direction, relative to the Earth's surface — horizontal E-field is horizontal polarisation, vertical E-field is vertical. It is referenced to the ground, not to compass north, and to the E-field, not the magnetic field.", - "source": "https://50ohm.de/E_polarisation_2.html", + "source": "https://50ohm.de/NEA_polarisation_2.html#EG222", "confidence": 8 }, "EG223": { - "revision": 3, + "revision": 4, "explanation": "An indoor transmitting antenna puts strong RF fields close to house wiring and consumer electronics, so those leads can act as unintended receiving antennas. Moving the antenna outdoors and away from installations reduces coupling and interference risk.", - "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_standortwahl.html#EG223", "confidence": 8 }, "EG301": { - "revision": 2, + "revision": 3, "explanation": "The characteristic impedance (Wellenwiderstand) is fixed by the line's geometry and dielectric — conductor spacing and insulation — not by what is connected at the far end. Across the HF range it is essentially constant and independent of the load, which is why a $50\\ \\Omega$ cable stays $50\\ \\Omega$ regardless of the antenna on it.", - "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_2.html#EG301", "confidence": 8 }, "EG302": { - "revision": 2, + "revision": 3, "explanation": "Good coaxial cable keeps the RF field trapped between inner conductor and shield, so in normal (common-mode-free) operation it radiates almost nothing. That makes it the right choice for HF links between station devices; open balanced feeders deliberately radiate from both wires and would couple into nearby equipment.", - "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_2.html#EG302", "confidence": 8 }, "EG303": { - "revision": 2, + "revision": 3, "explanation": "The N connector (N-Stecker) holds a defined $50\\ \\Omega$ impedance well into the GHz range and has the highest voltage rating of the four, so it handles high power best. SMA is small and fine to microwave but limited in power; BNC tops out lower; the UHF (PL) connector has no constant impedance and is unsuitable above a few hundred MHz.", - "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_2.html#EG303", "confidence": 8 }, "EG304": { - "revision": 2, - "explanation": "A feeder is unbalanced (unsymmetrisch) when its two conductors are not geometrically equivalent — as in coax, where a central inner conductor sits inside an outer shield at a different potential. A balanced line uses two identical, symmetric conductors instead. Reflection, resonance, and length do not define balance.", - "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "revision": 3, + "explanation": "A feeder is unbalanced (unsymmetrisch) when its two conductors are not geometrically equivalent — as in coax, where a central inner conductor sits inside an outer shield at a different potential. A balanced line uses two identical, symmetric conductors instead. Reflection, resonance, and length do not define balance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_2.html#EG304", "confidence": 8 }, "EG305": { - "revision": 2, + "revision": 3, "explanation": "Open parallel-wire line (Hühnerleiter/Paralleldraht) runs mostly through air rather than a lossy solid dielectric, so it has markedly lower loss than coax and withstands high voltages well — ideal for feeding a high-SWR multiband antenna. Its drawback is that it radiates if unbalanced, the opposite of the shielding option B claims.", - "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_2.html#EG305", "confidence": 8 }, "EG306": { - "revision": 2, + "revision": 3, "explanation": "Bundling RF feeders next to mains leads in one duct lets RF couple from the cable into the power wiring, carrying interference out onto the supply network. The realistic hazard is this conducted coupling/EMC problem, not flashover (voltages are modest) — neat cable management can quietly make interference worse.", - "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen_2.html#EG306", "confidence": 8 }, "EG307": { - "revision": 2, - "explanation": "Attenuations in dB add along the signal path. Treat each cable or inline loss as a positive dB loss and sum them; the losses in the shown station layout total 5 dB before antenna gain is considered.", - "source": "https://50ohm.de/EA_kabeldaempfung_1.html", + "revision": 4, + "explanation": "Attenuations in dB add along the signal path. Treat each cable or inline loss as a positive dB loss and sum them; the losses in the shown station layout total 5 dB before antenna gain is considered. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kabeldaempfung_1.html#EG307", "confidence": 8 }, "EG308": { - "revision": 2, - "explanation": "With SWR $= 1$ nothing is reflected, so the missing power is pure cable loss. Going from $100$ W to $50$ W is a factor of $2$, and $10\\log_{10}(2) \\approx 3$ dB of attenuation. (Attenuation is a positive loss figure, and dBm would be an absolute power, not a loss — so those options are wrong.)", - "source": "https://50ohm.de/EA_kabeldaempfung_1.html", + "revision": 4, + "explanation": "With SWR $= 1$ nothing is reflected, so the missing power is pure cable loss. Going from $100$ W to $50$ W is a factor of $2$, and $10\\log_{10}(2) \\approx 3$ dB of attenuation. (Attenuation is a positive loss figure, and dBm would be an absolute power, not a loss — so those options are wrong.) Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kabeldaempfung_1.html#EG308", "confidence": 8 }, "EG309": { - "revision": 2, - "explanation": "Attenuation in dB compares input to output power: $a = 10\\log_{10}(P_{\\text{in}}/P_{\\text{out}})$. Only a quarter remains, so the ratio is $4$, and $10\\log_{10}(4) \\approx 6$ dB. (Each halving is $3$ dB, and a quarter is two halvings, $3+3 = 6$ dB.)", - "source": "https://50ohm.de/EA_kabeldaempfung_1.html", + "revision": 4, + "explanation": "Attenuation in dB compares input to output power: $a = 10\\log_{10}(P_{\\text{in}}/P_{\\text{out}})$. Only a quarter remains, so the ratio is $4$, and $10\\log_{10}(4) \\approx 6$ dB. (Each halving is $3$ dB, and a quarter is two halvings, $3+3 = 6$ dB.) Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kabeldaempfung_1.html#EG309", "confidence": 8 }, "EG310": { - "revision": 2, - "explanation": "Using $a = 10\\log_{10}(P_{\\text{in}}/P_{\\text{out}})$ with only one tenth of the power left, the ratio is $10$ and $10\\log_{10}(10) = 10$ dB. The $\\times 10$-power $= +10$-dB anchor makes this one immediate.", - "source": "https://50ohm.de/EA_kabeldaempfung_1.html", + "revision": 4, + "explanation": "Using $a = 10\\log_{10}(P_{\\text{in}}/P_{\\text{out}})$ with only one tenth of the power left, the ratio is $10$ and $10\\log_{10}(10) = 10$ dB. The $\\times 10$-power $= +10$-dB anchor makes this one immediate. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kabeldaempfung_1.html#EG310", "confidence": 8 }, "EG311": { - "revision": 2, - "explanation": "For one cable at one frequency, attenuation in decibels is proportional to length. Scale directly: $20\\ \\text{dB} \\cdot (20\\ \\text{m} / 100\\ \\text{m}) = 4$ dB. Because dB already represents the loss logarithmically, you scale the dB value linearly with length — no powers needed.", - "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "revision": 4, + "explanation": "For one cable at one frequency, attenuation in decibels is proportional to length. Scale directly: $20\\ \\text{dB} \\cdot (20\\ \\text{m} / 100\\ \\text{m}) = 4$ dB. Because dB already represents the loss logarithmically, you scale the dB value linearly with length — no powers needed. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kabeldaempfung_1.html#EG311", "confidence": 8 }, "EG312": { - "revision": 2, - "explanation": "Read the cable-loss chart for RG58 (full-PE, $4.95$ mm) at $145$ MHz: about $20$ dB per $100$ m. The cable here is exactly $100$ m long, so the attenuation is that chart value, $20$ dB. (Thin RG58 is quite lossy at VHF — a good reason to use thicker cable on $2$ m.)", - "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "revision": 4, + "explanation": "Read the cable-loss chart for RG58 (full-PE, $4.95$ mm) at $145$ MHz: about $20$ dB per $100$ m. The cable here is exactly $100$ m long, so the attenuation is that chart value, $20$ dB. (Thin RG58 is quite lossy at VHF — a good reason to use thicker cable on $2$ m.) Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kabeldaempfung_1.html#EG312", "confidence": 8 }, "EG313": { - "revision": 2, - "explanation": "From the chart, RG58 at $145$ MHz is about $20$ dB per $100$ m. Attenuation scales with length, so $15$ m gives $20 \\cdot 15/100 = 3$ dB.", - "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "revision": 4, + "explanation": "From the chart, RG58 at $145$ MHz is about $20$ dB per $100$ m. Attenuation scales with length, so $15$ m gives $20 \\cdot 15/100 = 3$ dB. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kabeldaempfung_1.html#EG313", "confidence": 8 }, "EG314": { - "revision": 2, - "explanation": "From the chart, the thin RG174 ($2.8$ mm) at $145$ MHz is about $40$ dB per $100$ m — twice as lossy as RG58. Scaled to $50$ m: $40 \\cdot 50/100 = 20$ dB. Thinner cable means higher loss.", - "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "revision": 4, + "explanation": "From the chart, the thin RG174 ($2.8$ mm) at $145$ MHz is about $40$ dB per $100$ m — twice as lossy as RG58. Scaled to $50$ m: $40 \\cdot 50/100 = 20$ dB. Thinner cable means higher loss. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kabeldaempfung_1.html#EG314", "confidence": 8 }, "EG315": { - "revision": 2, - "explanation": "From the chart, the thick $12.7$ mm PE-foam cable at $435$ MHz is about $7$ dB per $100$ m. For $40$ m: $7 \\cdot 40/100 = 2.8$ dB. Larger diameter and foam dielectric keep the loss low even at UHF.", - "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "revision": 4, + "explanation": "From the chart, the thick $12.7$ mm PE-foam cable at $435$ MHz is about $7$ dB per $100$ m. For $40$ m: $7 \\cdot 40/100 = 2.8$ dB. Larger diameter and foam dielectric keep the loss low even at UHF. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kabeldaempfung_1.html#EG315", "confidence": 8 }, "EG316": { - "revision": 2, - "explanation": "From the chart, the $10.3$ mm PE-foam cable at $1296$ MHz is about $20.5$ dB per $100$ m — loss climbs steeply with frequency. For $40$ m: $20.5 \\cdot 40/100 \\approx 8.2$ dB.", - "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "revision": 4, + "explanation": "From the chart, the $10.3$ mm PE-foam cable at $1296$ MHz is about $20.5$ dB per $100$ m — loss climbs steeply with frequency. For $40$ m: $20.5 \\cdot 40/100 \\approx 8.2$ dB. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_kabeldaempfung_1.html#EG316", "confidence": 8 }, "EG401": { - "revision": 3, - "explanation": "At SWR $= 3$ the voltage reflection coefficient is $\\Gamma = (S-1)/(S+1) = (3-1)/(3+1) = 0.5$. Reflected power scales as $\\Gamma^2 = 0.25$, so $0.25 \\cdot 100$ W $= 25$ W travels back toward the transmitter.", - "source": "https://50ohm.de/NEA_swr.html", + "revision": 5, + "explanation": "At SWR $= 3$ the voltage reflection coefficient is $\\Gamma = (S-1)/(S+1) = (3-1)/(3+1) = 0.5$. Reflected power scales as $\\Gamma^2 = 0.25$, so $0.25 \\cdot 100$ W $= 25$ W travels back toward the transmitter. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_swr_2.html#EG401", "confidence": 8 }, "EG402": { - "revision": 3, + "revision": 4, "explanation": "Convert SWR to the voltage reflection coefficient $\\Gamma = (S-1)/(S+1) = (3-1)/(3+1) = 0.5$, then square it for power: $\\Gamma^2 = 0.25 = 25\\,\\%$ of the forward power is reflected. Power always goes with $\\Gamma^2$, not $\\Gamma$.", - "source": "https://50ohm.de/NEA_swr.html", + "source": "https://50ohm.de/NEA_swr_2.html#EG402", "confidence": 8 }, "EG403": { - "revision": 3, + "revision": 4, "explanation": "If $\\Gamma^2 = ((3-1)/(3+1))^2 = 0.25 = 25\\,\\%$ of the forward power is reflected, the rest reaches the load. Energy is conserved, so the delivered fraction is $1 - 0.25 = 75\\,\\%$.", - "source": "https://50ohm.de/NEA_swr.html", + "source": "https://50ohm.de/NEA_swr_2.html#EG403", "confidence": 8 }, "EG404": { - "revision": 2, - "explanation": "In normal coax operation, RF current flows on the inner conductor and the inside of the shield. Current on the outside of the shield is common-mode current, called Mantelstrom or mantle current; it can make the feed line radiate as part of the antenna.", - "source": "https://50ohm.de/NE_mantelwellen_1.html", + "revision": 3, + "explanation": "In normal coax operation, RF current flows on the inner conductor and the inside of the shield. Current on the outside of the shield is common-mode current, called Mantelstrom or mantle current; it can make the feed line radiate as part of the antenna. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_mantelwellen_1.html#EG404", "confidence": 8 }, "EG405": { - "revision": 2, + "revision": 3, "explanation": "Mantle waves (German Mantelwellen, common-mode currents on the coax outer braid) make the feed line itself radiate and receive as part of the antenna. That stray radiation can disturb nearby devices (EMC) and let household noise back into the receiver, worsening your own reception.", - "source": "https://50ohm.de/NE_mantelwellen_1.html", + "source": "https://50ohm.de/NEA_mantelwellen_1.html#EG405", "confidence": 8 }, "EG406": { - "revision": 2, + "revision": 3, "explanation": "A dipole is a symmetric (balanced) load, but coax is asymmetric (unbalanced). Feeding one directly with the other unbalances the currents, driving a common-mode current (Mantelwelle) on the braid. That braid current distorts the radiation pattern and radiates where it should not — which is exactly why a balun belongs at the feed point.", - "source": "https://50ohm.de/NE_mantelwellen_1.html", + "source": "https://50ohm.de/NEA_mantelwellen_1.html#EG406", "confidence": 8 }, "EG407": { - "revision": 3, + "revision": 4, "explanation": "A balun (balanced-unbalanced transformer, Symmetrierglied) joins a balanced antenna such as a dipole to an unbalanced feeder such as coax. By forcing equal and opposite currents at the feed point it suppresses common-mode current (Mantelwellen) on the braid.", - "source": "https://50ohm.de/NE_mantelwellen_1.html", + "source": "https://50ohm.de/NEA_mantelwellen_1.html#EG407", "confidence": 8 }, "EG408": { - "revision": 3, + "revision": 4, "explanation": "Coax turns on a ferrite core form a common-mode choke. The wanted differential-mode signal still travels inside the coax, but common-mode mantle current on the shield outside sees high impedance and is strongly reduced.", - "source": "https://50ohm.de/NE_mantelwellen_1.html", + "source": "https://50ohm.de/NEA_mantelwellen_1.html#EG408", "confidence": 8 }, "EG501": { - "revision": 3, + "revision": 4, "explanation": "EIRP (equivalent isotropically radiated power) is the power actually fed to the antenna multiplied by the antenna's gain in the chosen direction, with that gain referenced to an isotropic radiator. The traps: it uses average (not peak-envelope) power, and the reference is isotropic — referencing a dipole instead would give ERP.", - "source": "https://life.itu.int/radioclub/rr/art1.pdf", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG501", "confidence": 9 }, "EG502": { - "revision": 3, - "explanation": "Build EIRP in two steps. First get the real power at the antenna by subtracting feed-line losses from the transmitter output, $P_{\\text{Sender}} - P_{\\text{Verluste}}$; then multiply by the antenna gain factor $G$. Adding gain (options C/D) is the classic error — power and a linear gain factor multiply, not add (you would only add if everything were in dB).", - "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "revision": 4, + "explanation": "Build EIRP in two steps. First get the real power at the antenna by subtracting feed-line losses from the transmitter output, $P_{\\text{Sender}} - P_{\\text{Verluste}}$; then multiply by the antenna gain factor $G$. Adding gain (options C/D) is the classic error — power and a linear gain factor multiply, not add (you would only add if everything were in dB). Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG502", "confidence": 8 }, "EG503": { - "revision": 3, - "explanation": "Convert the gain from dB to a factor: $26\\ \\text{dBi} \\to 10^{26/10} = 10^{2.6} \\approx 398$. Then EIRP $= 0.25\\ \\text{W} \\cdot 398 \\approx 100$ W. Shortcut: $26$ dB $= 20 + 6$ dB $= \\times 100 \\cdot \\times 4 = \\times 400$.", - "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "revision": 5, + "explanation": "Convert the gain from dB to a factor: $26\\ \\text{dBi} \\to 10^{26/10} = 10^{2.6} \\approx 398$. Then EIRP $= 0.25\\ \\text{W} \\cdot 398 \\approx 100$ W. Shortcut: $26$ dB $= 20 + 6$ dB $= \\times 100 \\cdot \\times 4 = \\times 400$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG503", "confidence": 8 }, "EG504": { - "revision": 3, - "explanation": "Gain factor first: $36\\ \\text{dBi} \\to 10^{3.6} \\approx 3981$. EIRP $= 5\\ \\text{W} \\cdot 3981 \\approx 20000$ W. Shortcut: $36$ dB $= 30 + 6$ dB $= \\times 1000 \\cdot \\times 4 = \\times 4000$, and $5 \\cdot 4000 = 20000$ W.", - "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "revision": 5, + "explanation": "Gain factor first: $36\\ \\text{dBi} \\to 10^{3.6} \\approx 3981$. EIRP $= 5\\ \\text{W} \\cdot 3981 \\approx 20000$ W. Shortcut: $36$ dB $= 30 + 6$ dB $= \\times 1000 \\cdot \\times 4 = \\times 4000$, and $5 \\cdot 4000 = 20000$ W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG504", "confidence": 8 }, "EG505": { - "revision": 3, - "explanation": "Work in decibels, then convert once. Net gain toward isotropic $= 11\\ \\text{dBi} - 1\\ \\text{dB (cable)} = 10$ dB, which is a factor of $10$. So EIRP $= 100\\ \\text{W} \\cdot 10 = 1000$ W.", - "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "revision": 5, + "explanation": "Work in decibels, then convert once. Net gain toward isotropic $= 11\\ \\text{dBi} - 1\\ \\text{dB (cable)} = 10$ dB, which is a factor of $10$. So EIRP $= 100\\ \\text{W} \\cdot 10 = 1000$ W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG505", "confidence": 8 }, "EG506": { - "revision": 3, - "explanation": "A dipole has $2.15$ dBi gain (factor $1.64$), and here the cable loss is also $2.15$ dB (factor $1.64$). Gain and loss are equal and opposite, so they cancel exactly: EIRP $= 75$ W, the same as the transmitter output. A neat reminder that a lossy-fed dipole radiates about its raw power in EIRP terms.", - "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "revision": 4, + "explanation": "A dipole has $2.15$ dBi gain (factor $1.64$), and here the cable loss is also $2.15$ dB (factor $1.64$). Gain and loss are equal and opposite, so they cancel exactly: EIRP $= 75$ W, the same as the transmitter output. A neat reminder that a lossy-fed dipole radiates about its raw power in EIRP terms. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG506", "confidence": 8 }, "EG507": { - "revision": 3, - "explanation": "Two effects in turn: $10$ dB of cable loss cuts $100$ W down to $10$ W at the antenna, and the dipole then adds $2.15$ dBi (factor $1.64$) toward isotropic. EIRP $= 10\\ \\text{W} \\cdot 1.64 \\approx 16.4$ W.", - "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "revision": 5, + "explanation": "Two effects in turn: $10$ dB of cable loss cuts $100$ W down to $10$ W at the antenna, and the dipole then adds $2.15$ dBi (factor $1.64$) toward isotropic. EIRP $= 10\\ \\text{W} \\cdot 1.64 \\approx 16.4$ W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG507", "confidence": 8 }, "EG508": { - "revision": 3, - "explanation": "The gain is given in dBd, so first convert: $5\\ \\text{dBd} = 7.15$ dBi. Net of the $2$ dB cable loss, $7.15 - 2 = 5.15$ dB, a factor of $10^{0.515} \\approx 3.28$. EIRP $= 5\\ \\text{W} \\cdot 3.28 \\approx 16.4$ W.", - "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "revision": 5, + "explanation": "The gain is given in dBd, so first convert: $5\\ \\text{dBd} = 7.15$ dBi. Net of the $2$ dB cable loss, $7.15 - 2 = 5.15$ dB, a factor of $10^{0.515} \\approx 3.28$. EIRP $= 5\\ \\text{W} \\cdot 3.28 \\approx 16.4$ W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG508", "confidence": 8 }, "EG509": { - "revision": 3, - "explanation": "Convert the dipole-referenced gain: $11\\ \\text{dBd} = 13.15$ dBi. After $1$ dB cable loss, $13.15 - 1 = 12.15$ dB $\\to 10^{1.215} \\approx 16.4$. EIRP $= 0.6\\ \\text{W} \\cdot 16.4 \\approx 9.8$ W.", - "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "revision": 5, + "explanation": "Convert the dipole-referenced gain: $11\\ \\text{dBd} = 13.15$ dBi. After $1$ dB cable loss, $13.15 - 1 = 12.15$ dB $\\to 10^{1.215} \\approx 16.4$. EIRP $= 0.6\\ \\text{W} \\cdot 16.4 \\approx 9.8$ W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG509", "confidence": 8 }, "EG510": { - "revision": 3, - "explanation": "With $0$ dBd the antenna equals a dipole, i.e. $2.15$ dBi. Subtract the $1.5$ dB cable loss: $2.15 - 1.5 = 0.65$ dB $\\to 10^{0.065} \\approx 1.16$. EIRP $= 8.5\\ \\text{W} \\cdot 1.16 \\approx 9.9$ W.", - "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "revision": 5, + "explanation": "With $0$ dBd the antenna equals a dipole, i.e. $2.15$ dBi. Subtract the $1.5$ dB cable loss: $2.15 - 1.5 = 0.65$ dB $\\to 10^{0.065} \\approx 1.16$. EIRP $= 8.5\\ \\text{W} \\cdot 1.16 \\approx 9.9$ W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG510", "confidence": 8 }, "EG511": { - "revision": 2, - "explanation": "The BEMFV $\\S\\,9$ notification (Anzeige) for a fixed station is required once radiated power reaches $10$ W EIRP, so stay at or below it. Convert the gain: $5.15\\ \\text{dBi} \\to 10^{0.515} \\approx 3.28$. Working back, $P_{\\text{max}} = 10\\ \\text{W} / 3.28 \\approx 3$ W of transmitter power keeps you under the limit.", - "source": "https://www.gesetze-im-internet.de/bemfv/__9.html", + "revision": 4, + "explanation": "The BEMFV $\\S\\,9$ notification (Anzeige) for a fixed station is required once radiated power reaches $10$ W EIRP, so stay at or below it. Convert the gain: $5.15\\ \\text{dBi} \\to 10^{0.515} \\approx 3.28$. Working back, $P_{\\text{max}} = 10\\ \\text{W} / 3.28 \\approx 3$ W of transmitter power keeps you under the limit. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_2.html#EG511", "confidence": 9 }, "EH101": { - "revision": 2, + "revision": 3, "explanation": "HF long-distance propagation mainly uses sky waves, German Raumwellen. Ionized layers of the ionosphere contain free electrons that gradually bend/refract HF waves back toward Earth, enabling paths far beyond line of sight.", - "source": "https://50ohm.de/E_ionosphaere_2.html", + "source": "https://50ohm.de/NEA_ionosphaere_2.html#EH101", "confidence": 8 }, "EH102": { - "revision": 2, + "revision": 3, "explanation": "For HF DX, the important ionospheric regions are mainly the F regions, roughly 130 km to 450 km high. They are high enough that a refracted ray returns hundreds or thousands of kilometres away, while the lower D and E regions mainly affect absorption or shorter hops.", - "source": "https://50ohm.de/E_ionosphaere_2.html", + "source": "https://50ohm.de/NEA_ionosphaere_2.html#EH102", "confidence": 8 }, "EH103": { - "revision": 2, + "revision": 3, "explanation": "The F2 region is the highest and most persistent ionospheric region used for normal HF DX. Because it is high and often strongly ionized, it can bend HF waves back over long distances and supports multi-hop worldwide propagation.", - "source": "https://50ohm.de/E_ionosphaere_2.html", + "source": "https://50ohm.de/NEA_ionosphaere_2.html#EH103", "confidence": 8 }, "EH104": { - "revision": 2, + "revision": 3, "explanation": "On 80 m, daytime sky waves are often absorbed before they reach the useful refracting layer. At night the D region largely recombines and absorption drops, so the signal can reach the F2 region and return as DX.", - "source": "https://50ohm.de/E_ionosphaere_2.html", + "source": "https://50ohm.de/NEA_ionosphaere_2.html#EH104", "confidence": 8 }, "EH105": { - "revision": 2, + "revision": 3, "explanation": "The D region is the lowest ionospheric region and is produced mainly by daylight. It is not useful as a DX reflector; instead collisions in this dense lower atmosphere turn RF energy into heat, absorbing low HF especially on 160 m and 80 m during the day.", - "source": "https://50ohm.de/E_ionosphaere_2.html", + "source": "https://50ohm.de/NEA_ionosphaere_2.html#EH105", "confidence": 8 }, "EH106": { - "revision": 2, + "revision": 3, "explanation": "Sporadic-E is not the normal smooth E layer. It is patchy, dense ionization in the E region, often seasonal, that can refract much higher frequencies than usual, producing surprisingly short-to-medium paths on 10 m and sometimes VHF.", - "source": "https://50ohm.de/E_ionosphaere_2.html", + "source": "https://50ohm.de/NEA_ionosphaere_2.html#EH106", "confidence": 8 }, "EH107": { - "revision": 2, + "revision": 3, "explanation": "Solar activity follows the sunspot cycle, averaging about 11 years. More sunspots generally mean more solar UV/X-ray radiation, stronger ionization of the upper ionosphere, and better higher-HF propagation.", - "source": "https://50ohm.de/E_ionosphaere_2.html", + "source": "https://50ohm.de/NEA_ionosphaere_2.html#EH107", "confidence": 8 }, "EH201": { - "revision": 2, + "revision": 3, "explanation": "The dead zone, German tote Zone, is a geometry problem: the ground wave (Bodenwelle) has already become too weak, but the first sky-wave hop (Raumwelle) has not yet returned to Earth. Stations in that gap hear little or nothing even though stations farther away may be readable.", - "source": "https://50ohm.de/E_tote_zone_1.html", + "source": "https://50ohm.de/NEA_tote_zone_1.html#EH201", "confidence": 8 }, "EH202": { - "revision": 2, + "revision": 3, "explanation": "Where ground wave (Bodenwelle) and sky wave (Raumwelle) both reach the receiver, they are two versions of the same signal with different path lengths and phases. Their vector sum changes with ionospheric motion and frequency, causing reinforcement or cancellation: fading.", - "source": "https://50ohm.de/NE_fading.html", + "source": "https://50ohm.de/NEA_fading.html#EH202", "confidence": 8 }, "EH203": { - "revision": 2, + "revision": 3, "explanation": "Fading is signal-strength variation caused by multiple received paths adding with changing phase. If ground wave and sky wave overlap, they can sometimes reinforce and sometimes cancel, making the signal rise and fall.", - "source": "https://50ohm.de/NE_fading.html", + "source": "https://50ohm.de/NEA_fading.html#EH203", "confidence": 8 }, "EH204": { - "revision": 2, + "revision": 3, "explanation": "MUF means Maximum Usable Frequency. It is the highest frequency that the ionosphere can still refract back to Earth for a specific path; above the MUF the wave escapes instead of returning.", - "source": "https://50ohm.de/NE_muf_luf_1.html", + "source": "https://50ohm.de/NEA_muf_luf_1.html#EH204", "confidence": 8 }, "EH205": { - "revision": 2, + "revision": 3, "explanation": "At sunspot maximum, the Sun emits more UV and X-ray radiation that ionizes the upper atmosphere. The F region then has more free electrons, so it can refract higher HF frequencies that would otherwise pass through into space.", - "source": "https://50ohm.de/E_ionosphaere_2.html", + "source": "https://50ohm.de/NEA_ionosphaere_2.html#EH205", "confidence": 8 }, "EH206": { - "revision": 2, + "revision": 3, "explanation": "The MUF rises when the F2 region has a higher electron density. Physically, more free electrons change the refractive index more strongly, so even shorter-wavelength, higher-frequency HF waves can be bent back to Earth.", - "source": "https://50ohm.de/NE_muf_luf_1.html", + "source": "https://50ohm.de/NEA_muf_luf_1.html#EH206", "confidence": 8 }, "EH207": { - "revision": 2, + "revision": 3, "explanation": "If you want to use a frequency above the current MUF, the ionosphere must become more ionized or the path geometry must improve. Otherwise the wave is not bent enough and continues through the F region instead of returning.", - "source": "https://50ohm.de/NE_muf_luf_1.html", + "source": "https://50ohm.de/NEA_muf_luf_1.html#EH207", "confidence": 8 }, "EH208": { - "revision": 2, + "revision": 3, "explanation": "Skip distance, German Sprungdistanz, is mainly controlled by launch angle and layer height. A low takeoff angle hits the ionosphere far away and returns far away; a steep angle goes up and comes back sooner. This is why antenna elevation pattern matters for DX.", - "source": "https://50ohm.de/E_sprungdistanz_1.html", + "source": "https://50ohm.de/NEA_sprungdistanz_1.html#EH208", "confidence": 8 }, "EH209": { - "revision": 2, + "revision": 3, "explanation": "LUF means Lowest Usable Frequency, but it is not set by refraction like MUF. It is set mainly by absorption: if D-region loss is too high, lower-frequency signals are absorbed before completing the path, so the usable frequency must be raised.", - "source": "https://50ohm.de/NE_muf_luf_1.html", + "source": "https://50ohm.de/NEA_muf_luf_1.html#EH209", "confidence": 8 }, "EH210": { - "revision": 2, + "revision": 3, "explanation": "During daylight, the D region absorbs low-HF sky waves strongly. That makes 160 m and 80 m poor for daytime worldwide sky-wave communication even though those bands can be excellent after dark when D-region absorption collapses.", - "source": "https://50ohm.de/E_ionosphaere_2.html", + "source": "https://50ohm.de/NEA_ionosphaere_2.html#EH210", "confidence": 8 }, "EH211": { - "revision": 2, + "revision": 3, "explanation": "On 160 m in daytime, the ionosphere is often more of an absorber than a reflector. The D region eats the sky wave, so useful coverage is mainly by ground wave along the Earth's surface, usually over much shorter ranges.", - "source": "https://50ohm.de/E_bodenwelle.html", + "source": "https://50ohm.de/NEA_bodenwelle.html#EH211", "confidence": 8 }, "EH212": { - "revision": 2, + "revision": 3, "explanation": "A ground wave, German Bodenwelle, travels along the Earth's surface rather than being refracted by the ionosphere. It can reach beyond the optical horizon, especially at lower frequencies, but ground losses increase with frequency so higher-HF ground-wave range is limited.", - "source": "https://50ohm.de/E_bodenwelle.html", + "source": "https://50ohm.de/NEA_bodenwelle.html#EH212", "confidence": 8 }, "EH213": { - "revision": 2, + "revision": 3, "explanation": "Greyline propagation uses the sunrise/sunset transition. The D region, which causes much HF absorption, weakens quickly in twilight, while the F region can remain ionized enough to refract signals; that combination can briefly improve DX paths.", - "source": "https://50ohm.de/NE_greyline.html", + "source": "https://50ohm.de/NEA_greyline.html#EH213", "confidence": 8 }, "EH214": { - "revision": 2, + "revision": 3, "explanation": "A strong solar flare sends extra X-ray radiation to the sunlit side of Earth, abruptly increasing D-region ionization. Because the D region is absorptive for HF, sky-wave signals can disappear suddenly: the Moegel-Dellinger shortwave fadeout.", - "source": "https://50ohm.de/E_moegel_dellinger_effekt.html", + "source": "https://50ohm.de/NEA_moegel_dellinger_effekt.html#EH214", "confidence": 8 }, "EH215": { - "revision": 2, + "revision": 3, "explanation": "The Moegel-Dellinger effect is a shortwave fadeout after a strong solar flare. Extra X-ray radiation suddenly increases D-region ionization, causing heavy HF absorption and temporary loss or severe impairment of sky-wave propagation.", - "source": "https://50ohm.de/E_moegel_dellinger_effekt.html", + "source": "https://50ohm.de/NEA_moegel_dellinger_effekt.html#EH215", "confidence": 8 }, "EH216": { - "revision": 2, + "revision": 3, "explanation": "Short path is the smaller great-circle route to the other station; long path is the same great circle in the opposite direction around the larger side of Earth. Long path can work when illumination, greyline, or ionospheric conditions are better that way.", - "source": "https://50ohm.de/EA_langer_kurzer_weg_1.html", + "source": "https://50ohm.de/NEA_langer_kurzer_weg_1.html#EH216", "confidence": 8 }, "EH217": { - "revision": 2, + "revision": 3, "explanation": "VK is Australia. From Germany, the short path points generally east/southeast; the long path is the opposite great-circle direction, around the other side of Earth, so the route goes roughly over South America before reaching Australia.", - "source": "https://50ohm.de/EA_langer_kurzer_weg_1.html", + "source": "https://50ohm.de/NEA_langer_kurzer_weg_1.html#EH217", "confidence": 8 }, "EH218": { - "revision": 2, + "revision": 3, "explanation": "A normal F-layer 10 m hop is usually much longer. Short-skip contacts under 1000 km on 10 m point to sporadic-E, where a lower E-region ionization patch returns the signal after a shorter geometric path.", - "source": "https://50ohm.de/NE_sporadic_e_2.html", + "source": "https://50ohm.de/NEA_sporadic_e_2.html#EH218", "confidence": 8 }, "EH219": { - "revision": 2, + "revision": 3, "explanation": "The 10 m band needs a high MUF for normal worldwide F-layer propagation. Around sunspot maximum the F region is strongly ionized, so MUF often rises above 28 MHz and even low-power daytime DX can become possible.", - "source": "https://50ohm.de/E_ionosphaere_2.html", + "source": "https://50ohm.de/NEA_ionosphaere_2.html#EH219", "confidence": 8 }, "EH301": { - "revision": 2, + "revision": 3, "explanation": "The troposphere is the lowest atmospheric layer, where weather, temperature gradients, and humidity changes occur. For VHF/UHF radio this matters because refractive-index changes in this layer can bend, duct, or scatter signals.", - "source": "https://50ohm.de/NE_troposphaere_2.html", + "source": "https://50ohm.de/NEA_troposphaere_2.html#EH301", "confidence": 8 }, "EH302": { - "revision": 2, + "revision": 3, "explanation": "VHF/UHF normally behaves close to line-of-sight, but the troposphere can extend range. Temperature, humidity, and pressure gradients change refractive index, so signals may bend, scatter, or get trapped in ducts beyond the optical horizon.", - "source": "https://50ohm.de/NE_troposphaere_2.html", + "source": "https://50ohm.de/NEA_troposphaere_2.html#EH302", "confidence": 8 }, "EH303": { - "revision": 2, + "revision": 3, "explanation": "VHF long-distance contacts usually rely on tropospheric effects, not normal HF-style F-layer sky-wave propagation. Temperature inversions, ducts, and scatter in the lower atmosphere can bend or guide VHF/UHF signals beyond line of sight.", - "source": "https://50ohm.de/NE_troposphaere_2.html", + "source": "https://50ohm.de/NEA_troposphaere_2.html#EH303", "confidence": 8 }, "EH304": { - "revision": 2, + "revision": 3, "explanation": "Sporadic-E propagation comes from patchy, unusually dense ionization clouds in the E layer. These localized regions can refract upper-HF and sometimes VHF signals back to Earth over medium-distance paths.", - "source": "https://50ohm.de/NE_sporadic_e_2.html", + "source": "https://50ohm.de/NEA_sporadic_e_2.html#EH304", "confidence": 8 }, "EH305": { - "revision": 3, + "revision": 4, "explanation": "Auroral propagation scatters VHF signals from disturbed, moving ionized regions near the polar aurora. The rapid motion spreads and roughens the CW tone, so reports use readability and strength plus A for Aurora instead of a normal tone-quality number.", - "source": "https://50ohm.de/E_slide_e_wellenausbreitung.html", + "source": "https://50ohm.de/NEA_aurora_1.html#EH305", "confidence": 8 }, "EI101": { - "revision": 2, + "revision": 3, "explanation": "A voltmeter measures the voltage across a component, so it is wired in parallel with it. To avoid drawing significant current and disturbing the circuit, it must be high-impedance (hochohmig) — ideally infinite. (An ammeter is the opposite: in series and low-impedance.)", - "source": "https://50ohm.de/E_strom_spannung_messung_2.html", + "source": "https://50ohm.de/NEA_strom_spannung_messung_2.html#EI101", "confidence": 8 }, "EI102": { - "revision": 2, + "revision": 3, "explanation": "To verify Ohm's law, measure the same current that flows through the resistor and the voltage across that resistor. Therefore the ammeter goes in series with the resistor, while the voltmeter goes in parallel across it; then $R = U/I$ is meaningful.", - "source": "https://50ohm.de/E_strom_spannung_messung_2.html", + "source": "https://50ohm.de/NEA_strom_spannung_messung_2.html#EI102", "confidence": 8 }, "EI103": { - "revision": 2, - "explanation": "For an analog meter, first read the pointer as a fraction of full scale, then multiply by the selected range. The pointer is at about 29 percent of full scale, so on the 10 V range the value is $0.29 \\cdot 10 V = 2.9 V$.", - "source": "https://50ohm.de/NEA_zeigerinstrumente_ablesen.html", + "revision": 4, + "explanation": "For an analog meter, first read the pointer as a fraction of full scale, then multiply by the selected range. The pointer is at about 29 percent of full scale, so on the 10 V range the value is $0.29 \\cdot 10 V = 2.9 V$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zeigerinstrumente_ablesen.html#EI103", "confidence": 8 }, "EI104": { - "revision": 2, - "explanation": "The pointer fraction is independent of the selected range. With the pointer at about 29 percent of full scale and the range set to 300 V, the reading is $0.29 \\cdot 300 V \\approx 88 V$.", - "source": "https://50ohm.de/NEA_zeigerinstrumente_ablesen.html", + "revision": 4, + "explanation": "The pointer fraction is independent of the selected range. With the pointer at about 29 percent of full scale and the range set to 300 V, the reading is $0.29 \\cdot 300 V \\approx 88 V$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_zeigerinstrumente_ablesen.html#EI104", "confidence": 8 }, "EI201": { - "revision": 2, + "revision": 3, "explanation": "A vector network analyser measures complex (magnitude and phase) impedance and reflection versus frequency, so it directly reveals resonant frequencies and feed-point impedances of tuned circuits and antennas. It is not a time-domain scope, a spectral-purity checker, or an earth-resistance meter.", - "source": "https://50ohm.de/NEA_vna_1.html", + "source": "https://50ohm.de/NEA_vna_1.html#EI201", "confidence": 8 }, "EI202": { - "revision": 2, - "explanation": "Find a resonant frequency either by measuring $L$ and $C$ and computing $f_0 = 1/(2\\pi\\sqrt{LC})$, or directly by sweeping the circuit with a VNA and watching for the resonance dip/peak. A plain frequency counter or DMM cannot find a passive circuit's resonance on its own.", - "source": "https://50ohm.de/NEA_vna_1.html", + "revision": 3, + "explanation": "Find a resonant frequency either by measuring $L$ and $C$ and computing $f_0 = 1/(2\\pi\\sqrt{LC})$, or directly by sweeping the circuit with a VNA and watching for the resonance dip/peak. A plain frequency counter or DMM cannot find a passive circuit's resonance on its own. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_vna_1.html#EI202", "confidence": 8 }, "EI203": { - "revision": 2, + "revision": 3, "explanation": "A vector network analyzer (VNA) measures magnitude and phase, so it can derive complex impedance, not just signal level. That includes resistance, reactance, reflection coefficient, return loss, and SWR over frequency.", - "source": "https://50ohm.de/NEA_vna_1.html", + "source": "https://50ohm.de/NEA_vna_1.html#EI203", "confidence": 8 }, "EI204": { - "revision": 2, + "revision": 3, "explanation": "Measuring impedance is a core VNA function: it excites the device over frequency and compares incident and reflected waves to derive the complex impedance. Data rates, transmit power, and harmonics are jobs for other instruments.", - "source": "https://50ohm.de/NEA_vna_1.html", + "source": "https://50ohm.de/NEA_vna_1.html#EI204", "confidence": 8 }, "EI205": { - "revision": 2, + "revision": 3, "explanation": "A VNA must be calibrated at the intended reference plane, usually with open/short/load standards. Calibration removes systematic errors from cables, adapters, and the instrument so the displayed impedance belongs to the device under test.", - "source": "https://50ohm.de/NEA_vna_1.html", + "source": "https://50ohm.de/NEA_vna_1.html#EI205", "confidence": 8 }, "EI206": { - "revision": 2, + "revision": 3, "explanation": "Sanity-check the VNA with the three standard terminations: a matched load should read SWR near 1 (almost no reflection), while open circuit and short circuit reflect everything and read SWR toward infinity. Those three known states confirm the instrument and its calibration before you trust antenna readings.", - "source": "https://50ohm.de/NEA_vna_1.html", + "source": "https://50ohm.de/NEA_vna_1.html#EI206", "confidence": 8 }, "EI301": { - "revision": 3, - "explanation": "On an oscilloscope, time is read horizontally. One full sine period spans 8 divisions, and the timebase is 0.5 ms/div, so $T = 8 \\cdot 0.5 ms = 4 ms$.", - "source": "https://50ohm.de/NE_oszilloskop_1.html", + "revision": 5, + "explanation": "On an oscilloscope, time is read horizontally. One full sine period spans 8 divisions, and the timebase is 0.5 ms/div, so $T = 8 \\cdot 0.5 ms = 4 ms$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_oszilloskop_1.html#EI301", "confidence": 8 }, "EI302": { - "revision": 3, - "explanation": "Frequency is the reciprocal of period: $f=1/T$. From the oscilloscope reading $T=4 ms = 0.004 s$, so $f=1/0.004 s = 250 Hz$.", - "source": "https://50ohm.de/NE_oszilloskop_1.html", + "revision": 5, + "explanation": "Frequency is the reciprocal of period: $f=1/T$. From the oscilloscope reading $T=4 ms = 0.004 s$, so $f=1/0.004 s = 250 Hz$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_oszilloskop_1.html#EI302", "confidence": 8 }, "EI303": { - "revision": 3, + "revision": 4, "explanation": "Pulse duration is conventionally measured between the 50 percent points of the rising and falling edges, not from the first visible slope to the last. Reading those midpoint crossings on the oscilloscope gives 200 microseconds.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "source": "https://50ohm.de/NEA_oszilloskop_2.html#EI303", "confidence": 8 }, "EI304": { - "revision": 3, + "revision": 4, "explanation": "Audio distortion changes the time-domain waveform: clipping flattens peaks, nonlinear stages bend the sine shape, and hum/noise adds visible components. An oscilloscope displays that waveform directly, so it is the right tool for seeing distortion.", - "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "source": "https://50ohm.de/NEA_oszilloskop_1.html#EI304", "confidence": 8 }, "EI401": { - "revision": 3, + "revision": 4, "explanation": "An SWR meter compares forward and reflected power on the feed line, which reveals how well the antenna system is matched (Antennenanpassung). A bad match sends power back; a good match (SWR near 1) does not. It does not measure harmonics, bandwidth, or efficiency.", - "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_swr_meter_1.html#EI401", "confidence": 8 }, "EI402": { - "revision": 3, + "revision": 4, "explanation": "To show the match between a UHF transmitter and its feed line you use an SWR meter, which senses forward versus reflected waves. An ohmmeter cannot measure RF impedance, and the other options are not measuring instruments for this.", - "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_swr_meter_1.html#EI402", "confidence": 8 }, "EI403": { - "revision": 3, + "revision": 4, "explanation": "On transmit, SWR is read with an SWR bridge (SWR-Messbrücke / directional coupler) that samples forward and reflected power while the signal is live. A simple current or voltage reading at the line ends cannot separate forward from reflected waves, and an absorption wavemeter measures frequency, not SWR.", - "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_swr_meter_1.html#EI403", "confidence": 8 }, "EI404": { - "revision": 3, + "revision": 4, "explanation": "Insert the SWR meter as close to the antenna as possible — between antenna cable and antenna — so it reports the antenna's own match. Placed at the transmitter end, cable loss masks the reflected wave and flatters the reading, and a tuner in between would hide the real antenna SWR.", - "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_swr_meter_1.html#EI404", "confidence": 8 }, "EI405": { - "revision": 3, + "revision": 4, "explanation": "If you want to know what match the transmitter actually sees, place the SWR meter at the transmitter output. Then the meter includes the combined effect of feed line, tuner, and antenna as seen by the transmitter; in the diagram that is point 1.", - "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_swr_meter_1.html#EI405", "confidence": 8 }, "EI501": { - "revision": 2, + "revision": 3, "explanation": "A frequency counter counts zero crossings or cycles during a gate time. An unmodulated RF carrier has one stable frequency, so the counter can measure it directly; modulated or unstable signals are harder to count cleanly.", - "source": "https://50ohm.de/NE_frequenzmessung_1.html", + "source": "https://50ohm.de/NEA_frequenzmessung_1.html#EI501", "confidence": 8 }, "EI502": { - "revision": 2, + "revision": 3, "explanation": "A frequency counter display is read by decimal place value. The marked digit is in the $10^3$ Hz position, so changing that digit changes the reading by 1000 Hz, which is one kilohertz.", - "source": "https://50ohm.de/NE_frequenzmessung_1.html", + "source": "https://50ohm.de/NEA_frequenzmessung_1.html#EI502", "confidence": 8 }, "EI503": { - "revision": 2, + "revision": 3, "explanation": "Read the marked counter digit by its decimal place. In this display the marked position is $10^1$ Hz, so one count in that digit corresponds to 10 Hz.", - "source": "https://50ohm.de/NE_frequenzmessung_1.html", + "source": "https://50ohm.de/NEA_frequenzmessung_1.html#EI503", "confidence": 8 }, "EI504": { - "revision": 2, - "explanation": "A 10:1 prescaler (Frequenzteiler) divides the input frequency by ten before the counter sees it, so the display reads one tenth of the true value. Multiply back: $10 \\cdot 14.5625\\ \\text{MHz} = 145.625$ MHz. Prescalers are used precisely so a slower counter can measure high (VHF) frequencies.", - "source": "https://50ohm.de/NE_frequenzmessung_1.html", + "revision": 4, + "explanation": "A 10:1 prescaler (Frequenzteiler) divides the input frequency by ten before the counter sees it, so the display reads one tenth of the true value. Multiply back: $10 \\cdot 14.5625\\ \\text{MHz} = 145.625$ MHz. Prescalers are used precisely so a slower counter can measure high (VHF) frequencies. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenzmessung_1.html#EI504", "confidence": 8 }, "EJ101": { - "revision": 2, + "revision": 3, "explanation": "Einströmung (conducted ingress) is RF getting into a device through its attached wires — mains lead, speaker, or signal cables acting as receiving antennas. It is conducted in via cables, distinct from radiated pickup through a poorly shielded case.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ101", "confidence": 8 }, "EJ102": { - "revision": 2, + "revision": 3, "explanation": "Einstrahlung means radiated RF coupling directly into equipment, usually through inadequate enclosure shielding or circuit layout. That is different from Einströmung, where RF is conducted into the device through attached leads.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ102", "confidence": 8 }, "EJ103": { - "revision": 2, + "revision": 3, "explanation": "A perfectly clean transmitted signal can still overload the front end of a nearby receiver tuned elsewhere, desensitising it or producing spurious responses inside that receiver. This is overload/disturbing influence (Übersteuerung) — the fault is the victim's selectivity, not any unwanted emission from your transmitter.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ103", "confidence": 8 }, "EJ104": { - "revision": 2, + "revision": 3, "explanation": "Interference scales with the field strength you radiate, so the standard good-practice rule is to use only the minimum power needed for satisfactory communication. Running full legal power 'because it is allowed' needlessly raises the interference probability.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ104", "confidence": 8 }, "EJ105": { - "revision": 2, + "revision": 3, "explanation": "In a built-up area during peak TV-viewing hours, the same minimum-power principle applies: transmit with no more power than reliable communication requires. Lowering the antenna or insisting on a high-gain beam are not the recommended courtesy measure — reducing power is.", - "source": "https://50ohm.de/NE_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ105", "confidence": 8 }, "EJ106": { - "revision": 2, + "revision": 3, "explanation": "A high-gain $432$ MHz beam aimed straight at a TV antenna delivers a very strong local field into the TV's input, overloading its front end (Übersteuerung). The TV receiver, not your transmitter, is the limiting part — its input cannot handle the huge nearby signal even though your emission is clean.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ106", "confidence": 8 }, "EJ107": { - "revision": 2, + "revision": 3, "explanation": "Receiver overload happens when a strong signal drives the RF input, mixer, or amplifier outside its linear range. The receiver then creates distortion or desensitization, so effective sensitivity drops or reception can be blocked.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ107", "confidence": 8 }, "EJ108": { - "revision": 2, + "revision": 3, "explanation": "A conductive metal enclosure acts as RF shielding by giving induced RF currents a path around the electronics instead of through them. It must be nearly closed and well bonded, because gaps, long leads, and slots can leak RF.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ108", "confidence": 8 }, "EJ109": { - "revision": 2, + "revision": 3, "explanation": "An HF antenna running close and parallel to a $230$ V mains line couples to it like a transformer/capacitor, inducing RF currents into the power wiring. From there the RF spreads and can disturb other devices. The effect is RF ingress into the mains, not mains overvoltage or harmonics.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ109", "confidence": 8 }, "EJ110": { - "revision": 2, + "revision": 3, "explanation": "In a terraced house, run the $80$ m wire at right angles to the row so it does not lie long and parallel to the neighbours' wiring and antennas — parallel runs maximise coupling, perpendicular minimises it. Placing it by the shared chimney next to the TV antenna would do the opposite.", - "source": "https://50ohm.de/E_standortwahl.html", + "source": "https://50ohm.de/NEA_standortwahl.html#EJ110", "confidence": 8 }, "EJ111": { - "revision": 2, + "revision": 3, "explanation": "Give transmitting antennas their own separate RF earth so antenna return currents flow there rather than through the house wiring and protective-earth network. Keeping RF out of the building's wiring is what lowers in-house interference; a water pipe or the mains PE is not a proper RF earth.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ111", "confidence": 8 }, "EJ112": { - "revision": 2, + "revision": 3, "explanation": "The susceptible device is the mains-powered LED lamp: its built-in switch-mode electronics can rectify and respond to strong RF. The purely thermal iron (bimetal) and the plain commutator/AC motors have no sensitive electronics to be disturbed.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ112", "confidence": 8 }, "EJ113": { - "revision": 2, + "revision": 3, "explanation": "Strong RF picked up on speaker or mains leads can be rectified at non-linear semiconductor junctions in the audio output stage, turning your modulation into audible sound even with the set switched off. Demodulation by an unintended detector is the classic audio-rectification (BCI) mechanism.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ113", "confidence": 8 }, "EJ114": { - "revision": 2, + "revision": 3, "explanation": "The RF is entering through the speaker leads into the audio power stage, so screen that path: shielded speaker cable (plus a common-mode choke) blocks the conducted RF. Filtering the coax or the receiver mains lead would not help, because those are not the entry route here.", - "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ114", "confidence": 8 }, "EJ115": { - "revision": 2, + "revision": 3, "explanation": "The interfering RF is conducted in on the intercom's wiring, so a shielded connecting cable (ideally with a ferrite choke) reduces the pickup that carries RF into the door-phone electronics. Changing cable length or conductor material does not address the coupling.", - "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ115", "confidence": 8 }, "EJ116": { - "revision": 2, + "revision": 3, "explanation": "The wanted DVB-T2 signals are UHF, while the interferer is the much lower $28$ MHz amateur signal. A high-pass filter at the TV antenna input passes the high UHF channels but strongly attenuates $28$ MHz, removing the overload. A low-pass would do the reverse.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ116", "confidence": 8 }, "EJ117": { - "revision": 2, + "revision": 3, "explanation": "TV antenna signals are at much higher frequencies than HF amateur signals. A high-pass filter passes the wanted TV band but rejects lower-frequency HF energy conducted on the antenna lead, so it reduces the interference path.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ117", "confidence": 8 }, "EJ118": { - "revision": 2, + "revision": 3, "explanation": "A common-mode (mantle-wave) choke (Mantelwellendrossel) on the coax presents a high impedance only to common-mode RF current flowing on the outside of the braid, choking it off, while the wanted differential signal inside passes freely. It targets RF common-mode interference, not mains hum or low-frequency noise.", - "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ118", "confidence": 8 }, "EJ119": { - "revision": 2, + "revision": 3, "explanation": "The $144$ MHz energy is riding as common-mode current on the outside of the broadcast receiver's coax. A common-mode choke (Mantelwellendrossel) fitted just before the receiver raises the impedance to that current and suppresses it — without disconnecting the screen or the transmitter earth, which would be unsafe and ineffective.", - "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ119", "confidence": 8 }, "EJ120": { - "revision": 2, + "revision": 3, "explanation": "Intermodulation occurs in a nonlinear device when two or more strong signals mix and create new frequencies such as $2f_1-f_2$ or $f_1+f_2$. If one participating signal is removed, that particular phantom product disappears.", - "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ120", "confidence": 8 }, "EJ121": { - "revision": 2, + "revision": 3, "explanation": "A corroded joint forms a non-linear (rectifying) metal contact. Combined with a strong nearby transmitter signal it acts as an unintended mixer/diode, generating intermodulation products that fall on and disturb TV channels — the classic 'rusty-bolt effect'. The fix is to remake the corroded connection.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ121", "confidence": 8 }, "EJ122": { - "revision": 2, + "revision": 3, "explanation": "Before changing equipment or blaming a transmitter, establish correlation. If the disturbance appears only during your transmissions and disappears when you stop, you have useful evidence; if not, the source may be unrelated.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ122", "confidence": 8 }, "EJ123": { - "revision": 3, + "revision": 4, "explanation": "An indoor antenna sits in the neighbour's noisy near field and captures little wanted signal, so the interference-to-signal ratio is poor. An outdoor antenna can be sited away from the interferer, higher and directional, raising wanted signal and lowering pickup of the local transmitter — the most effective remedy here.", - "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ123", "confidence": 8 }, "EJ124": { - "revision": 2, + "revision": 3, "explanation": "Once cooperative, technically reasonable mitigation has genuinely failed, the correct next step is to ask the responsible BNetzA field office (Außenstelle der Bundesnetzagentur) to investigate. Opening and earthing the neighbour's TV yourself is neither permitted nor a proper diagnosis.", - "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "source": "https://50ohm.de/NEA_stoerungen_elektronischer_geraete_1.html#EJ124", "confidence": 8 }, "EJ201": { - "revision": 2, + "revision": 3, "explanation": "A pure sine wave contains only its single fundamental frequency; any distorted (square, triangle) waveform is mathematically a fundamental plus harmonics (Fourier). To avoid radiating harmonics, the carrier should therefore be as sinusoidal as possible — clean shape means clean spectrum.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ201", "confidence": 8 }, "EJ202": { - "revision": 2, + "revision": 3, "explanation": "Harmonics (Oberwellen) are unwanted whole-number multiples of the operating frequency, all above it. A harmonic filter (a low-pass, the 'Oberwellenfilter') removes them while passing the fundamental. An IF or adjacent-channel filter addresses different problems.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ202", "confidence": 8 }, "EJ203": { - "revision": 2, + "revision": 3, "explanation": "Harmonics are multiples above the wanted transmit frequency, such as $2f$ and $3f$. A low-pass filter passes the fundamental output while attenuating those higher-frequency harmonic components before they reach the antenna.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ203", "confidence": 8 }, "EJ204": { - "revision": 2, + "revision": 3, "explanation": "Harmonics lie at $2f$, $3f$, … above the operating frequency, so a low-pass filter between transmitter and antenna passes the fundamental and attenuates everything higher. That is the standard harmonic-suppression filter; a high-pass would remove the wanted signal instead.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ204", "confidence": 8 }, "EJ205": { - "revision": 2, + "revision": 3, "explanation": "A UHF transmitter's harmonics sit at even higher frequencies, so a low-pass filter after the transmitter passes the wanted UHF output and rejects the harmonics above it. Filters placed before the transmitter, or high-pass/notch types, cannot do this job.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ205", "confidence": 8 }, "EJ206": { - "revision": 2, + "revision": 3, "explanation": "A transmitter harmonic filter is normally a low-pass output filter: it passes the wanted fundamental frequency but attenuates higher harmonics. The circuit cue is series inductors plus shunt capacitors, where high-frequency energy is increasingly blocked and bypassed to ground.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ206", "confidence": 8 }, "EJ207": { - "revision": 2, + "revision": 3, "explanation": "Harmonics are integer multiples of the transmit frequency, so they lie above the wanted fundamental. A harmonic-reduction filter for a transmitter should therefore have a low-pass characteristic: pass the operating range, roll off above it.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ207", "confidence": 8 }, "EJ208": { - "revision": 2, + "revision": 3, "explanation": "For an HF multiband transmitter, the filter must pass the whole wanted HF operating range but attenuate harmonics above it. That is the wide low-pass response: broad passband across HF, then strong attenuation at higher frequencies.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ208", "confidence": 8 }, "EJ209": { - "revision": 2, + "revision": 3, "explanation": "Unwanted-emission power is measured at the transmitter output including the devices normally in line during operation — the SWR meter and any low-pass/harmonic filter — because those affect what actually reaches the antenna. The compliance figure must reflect the real transmitting configuration.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ209", "confidence": 8 }, "EJ210": { - "revision": 2, + "revision": 3, "explanation": "In SSB, RF occupied bandwidth follows the speech/audio bandwidth. Keeping the transmitted sideband to about 2.7 kHz avoids unnecessary high-audio components and reduces spillover into adjacent channels.", - "source": "https://50ohm.de/E_ssb_2.html", + "source": "https://50ohm.de/NEA_ssb_2.html#EJ210", "confidence": 8 }, "EJ211": { - "revision": 2, + "revision": 3, "explanation": "In SSB the RF sideband width equals the audio bandwidth, so limiting the highest transmitted audio (NF) frequency to under about $3$ kHz keeps the occupied bandwidth tight and limits splatter onto adjacent frequencies. Allowing $5$ or $10$ kHz of audio would needlessly widen the signal.", - "source": "https://50ohm.de/E_ssb_2.html", + "source": "https://50ohm.de/NEA_ssb_2.html#EJ211", "confidence": 8 }, "EJ212": { - "revision": 2, + "revision": 3, "explanation": "For FM AFSK, occupied bandwidth rises with frequency deviation. In German this deviation is Hub or Frequenzhub: the carrier swing caused by the audio tones. Lowering audio drive reduces the Hub and therefore narrows the transmitted FM signal.", - "source": "https://50ohm.de/EA_fm_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ212", "confidence": 8 }, "EJ213": { - "revision": 2, + "revision": 3, "explanation": "A power amplifier should operate in its intended linear range for linear modes. Overdrive pushes it into compression or clipping, creating harmonics and intermodulation products, which appear as unwanted emissions.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ213", "confidence": 8 }, "EJ214": { - "revision": 2, + "revision": 3, "explanation": "SSB needs linear amplification because the envelope carries information. If the linear amplifier is overdriven, nonlinear mixing of the speech components creates intermodulation products, heard as splatter on neighboring frequencies.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ214", "confidence": 8 }, "EJ215": { - "revision": 2, + "revision": 3, "explanation": "Excess microphone gain overdrives the SSB modulator or later amplifier stages. The result is flat-topping and intermodulation, so the transmitted signal becomes wider than necessary and causes splatter near the operating frequency.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_ssb_2.html#EJ215", "confidence": 8 }, "EJ216": { - "revision": 2, + "revision": 3, "explanation": "Frequency stability is the transmitter's ability to stay on its assigned frequency despite temperature, supply, or time changes. If it drifts, the emission can move into another channel or even outside the authorized amateur band.", - "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_2.html#EJ216", "confidence": 8 }, "EJ217": { - "revision": 2, + "revision": 3, "explanation": "If ALC clamps the peaks of a digital SSB signal (RTTY, FT8, Olivia), it distorts the envelope and generates intermodulation products that splatter onto neighbouring frequencies. The damage shows up as interference on adjacent channels, the hallmark of an over-driven digimode signal.", - "source": "https://50ohm.de/NEA_digimode_ssb.html", + "source": "https://50ohm.de/NEA_digimod_uebersteuerung.html#EJ217", "confidence": 8 }, "EJ218": { - "revision": 2, - "explanation": "For FT8, JS8, PSK31 and similar modes, set the audio (NF) drive low enough that the ALC does not engage at all. ALC action on these constant-envelope digital signals causes distortion and splatter, so the clean operating point is just below the ALC threshold — not at maximum.", - "source": "https://50ohm.de/NEA_digimode_ssb.html", + "revision": 3, + "explanation": "For FT8, JS8, PSK31 and similar modes, set the audio (NF) drive low enough that the ALC does not engage at all. ALC action on these constant-envelope digital signals causes distortion and splatter, so the clean operating point is just below the ALC threshold — not at maximum. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_digimod_uebersteuerung.html#EJ218", "confidence": 8 }, "EJ219": { - "revision": 2, + "revision": 3, "explanation": "When ALC action is causing splatter in a digital mode, the fix is to reduce the audio (NF) input level until the ALC no longer engages, restoring a clean envelope. Raising power, disabling the harmonic filter, or using RIT would not address the over-drive cause.", - "source": "https://50ohm.de/NEA_digimode_ssb.html", + "source": "https://50ohm.de/NEA_digimod_uebersteuerung.html#EJ219", "confidence": 8 }, "EK101": { - "revision": 2, + "revision": 3, "explanation": "RF energy absorption in the human body depends on frequency. Penetration depth, body-size resonance, and tissue heating efficiency change with wavelength, so safety limits are frequency-dependent rather than one fixed field value for all bands.", - "source": "https://50ohm.de/E_personenschutzabstand_grenzwerte.html", + "source": "https://50ohm.de/NEA_personenschutzabstand_grenzwerte.html#EK101", "confidence": 8 }, "EK102": { - "revision": 2, + "revision": 3, "explanation": "The 26th BImSchV applies different time references by annex: Annex 1b limits are RMS-averaged over $6$ minutes, Annex 1a limits are taken as a short-term RMS value, and Annex 3 (pulsed fields) uses the instantaneous peak value. The trap option swaps the $6$-minute window for $3$ minutes.", - "source": "https://www.gesetze-im-internet.de/bimschv_26/BJNR196600996.html", + "source": "https://50ohm.de/NEA_personenschutzabstand_grenzwerte.html#EK102", "confidence": 9 }, "EK103": { - "revision": 2, + "revision": 3, "explanation": "For people with active implants (aktive Körperhilfen, e.g. pacemakers) the protective criterion is the maximum instantaneous field value, not a time average — a single peak could disrupt the device, so averaging over $3$ or $6$ minutes would not be safe.", - "source": "https://50ohm.de/E_personenschutzabstand_grenzwerte.html", + "source": "https://50ohm.de/NEA_personenschutzabstand_grenzwerte.html#EK103", "confidence": 8 }, "EK104": { - "revision": 2, + "revision": 3, "explanation": "Yes. Convert the gain: $13\\ \\text{dBd} = 15.15$ dBi $\\to 10^{1.515} \\approx 32.7$, so EIRP $= 6\\ \\text{W} \\cdot 32.7 \\approx 196$ W. That is far above the $10$ W EIRP threshold at which a fixed station must demonstrate compliance with the person-protection limits — so proof is required regardless of mode or duty cycle.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_personenschutzabstand_2.html#EK104", "confidence": 9 }, "EK105": { - "revision": 2, - "explanation": "At 80 m, a 3.65 m distance is still in the reactive near field. In this region electric and magnetic fields are not yet locked into a stable far-field wave impedance, so the simple far-field power-density approximation is invalid; use measurement, simulation, or near-field calculation.", - "source": "https://50ohm.de/E_naeherungsformel_1.html", + "revision": 3, + "explanation": "At 80 m, a 3.65 m distance is still in the reactive near field. In this region electric and magnetic fields are not yet locked into a stable far-field wave impedance, so the simple far-field power-density approximation is invalid; use measurement, simulation, or near-field calculation. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_naeherungsformel_1.html#EK105", "confidence": 8 }, "EK106": { - "revision": 2, + "revision": 3, "explanation": "The reactive near-field boundary is roughly $r \\approx \\lambda/(2\\pi)$. Below that distance the E-field and H-field can vary independently and the far-field approximation is unreliable; for 160 m this is about 25.5 m, and for 80 m about 12.7 m.", - "source": "https://50ohm.de/E_naeherungsformel_1.html", + "source": "https://50ohm.de/NEA_naeherungsformel_1.html#EK106", "confidence": 8 }, "EK107": { - "revision": 3, + "revision": 4, "explanation": "With a far-field-based calculation, the safety distance (Sicherheitsabstand) must be kept from every radiating point of the antenna, since any part can radiate. Measuring only from the feed point or mast attachment would underestimate the exposure near the antenna's ends.", - "source": "https://50ohm.de/NEA_slide_nea_personenschutzabstand.html", + "source": "https://50ohm.de/NEA_personenschutzabstand_2.html#EK107", "confidence": 8 }, "EK108": { - "revision": 2, - "explanation": "Build the net gain: $7.5\\ \\text{dBd} = 9.65$ dBi, minus $1.5$ dB cable loss $= 8.15$ dBi $\\to$ factor $\\approx 6.53$, so EIRP $= 100\\ \\text{W} \\cdot 6.53 \\approx 653$ W. The far-field distance for a field-strength limit is $d = \\sqrt{30 \\cdot P_{\\text{EIRP}}} / E = \\sqrt{30 \\cdot 653} / 28 \\approx 140 / 28 \\approx 5.0$ m.", - "source": "https://50ohm.de/E_naeherungsformel_1.html", + "revision": 3, + "explanation": "Build the net gain: $7.5\\ \\text{dBd} = 9.65$ dBi, minus $1.5$ dB cable loss $= 8.15$ dBi $\\to$ factor $\\approx 6.53$, so EIRP $= 100\\ \\text{W} \\cdot 6.53 \\approx 653$ W. The far-field distance for a field-strength limit is $d = \\sqrt{30 \\cdot P_{\\text{EIRP}}} / E = \\sqrt{30 \\cdot 653} / 28 \\approx 140 / 28 \\approx 5.0$ m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_naeherungsformel_1.html#EK108", "confidence": 8 }, "EK201": { - "revision": 2, + "revision": 3, "explanation": "Microwave dish and horn antennas concentrate their power into a narrow, intense beam, so the field on the beam axis can far exceed the exposure limits close in. The key safety rule is to avoid being in the direct beam path of transmitting antennas; shielding hats or 'EMC clothing' are not real protection, and duty cycle is not the point.", - "source": "https://50ohm.de/NE_strahlengang_aufenthalt.html", + "source": "https://50ohm.de/NEA_strahlengang_aufenthalt.html#EK201", "confidence": 8 }, "EK202": { - "revision": 2, + "revision": 3, "explanation": "A transmitting antenna carries high RF voltages on its conductors, especially at voltage antinodes. Touching it can give RF burns and other injuries — and unlike DC, the skin effect does not protect you. Earthing for lightning does not remove the RF voltage present while transmitting.", - "source": "https://50ohm.de/E_slide_e_sicherheit.html?print-pdf=&showNotes=true", + "source": "https://50ohm.de/NEA_antennen_beruehrung_1.html#EK202", "confidence": 8 }, "EK203": { - "revision": 2, + "revision": 3, "explanation": "Even with the mains plug pulled, the smoothing/filter capacitors in the power supply can stay charged to a few hundred volts and deliver a dangerous shock. Always treat a just-opened supply as live and discharge the large capacitors before touching the circuit.", - "source": "https://50ohm.de/NEA_slide_nea_sicherheit.html?print-pdf=&showNotes=true", + "source": "https://50ohm.de/NEA_elektrische_geaete_oeffnen_1.html#EK203", "confidence": 8 }, "EK204": { - "revision": 2, + "revision": 3, "explanation": "A fuse is a calibrated safety device: replace it with the same current rating and the same tripping characteristic. A 20 A fast-blow ('flink') must be replaced by another 20 A fast-blow — a slower characteristic or a wire bridge would let fault current run too long and could start a fire.", - "source": "https://50ohm.de/E_sicherungen.html", + "source": "https://50ohm.de/NEA_sicherungen.html#EK204", "confidence": 8 }, "EK205": { - "revision": 2, + "revision": 3, "explanation": "German/IEC mains colour code: protective earth (Schutzleiter) is green-yellow, the live conductor (Außenleiter) is brown, and neutral (Neutralleiter) is blue. In the requested order PE, L, N that is green-yellow, brown, blue.", - "source": "https://50ohm.de/E_spannungsquelle.html", + "source": "https://50ohm.de/NEA_spannungsquelle.html#EK205", "confidence": 8 }, "EK206": { - "revision": 2, + "revision": 3, "explanation": "An ungrounded wire antenna is an isolated metal collector: precipitation such as rain or hail deposits electric charge on it, which can build up to a dangerous static voltage with no path to drain. That charge hazard, not transmit voltage or solar storms, is the special concern.", - "source": "https://50ohm.de/E_slide_e_sicherheit.html?print-pdf=&showNotes=true", + "source": "https://50ohm.de/NEA_statische_aufladung.html#EK206", "confidence": 8 }, "EK207": { - "revision": 2, + "revision": 3, "explanation": "Fit a high-value bleed resistor (hochohmiger Ableitwiderstand) from the antenna to station earth. Its high resistance quietly drains static charge to ground at DC, yet looks like a near-open circuit at RF, so it does not load or detune the antenna. A low-value resistor would short the signal.", - "source": "https://50ohm.de/NE_slide_ne_sicherheit.html?print-pdf=&showNotes=true", + "source": "https://50ohm.de/NEA_statische_aufladung.html#EK207", "confidence": 8 }, "EK208": { - "revision": 2, + "revision": 3, "explanation": "Bond the shields of all antenna coax cables together and to the main earthing bar (Haupterdungsschiene). Tying them to one common potential prevents dangerous voltage differences between cable systems during a fault or lightning surge — equipotential bonding is the person-protection measure here.", - "source": "https://50ohm.de/NE_slide_ne_sicherheit.html", + "source": "https://50ohm.de/NEA_schutzerdung_1.html#EK208", "confidence": 8 }, "EK209": { - "revision": 3, + "revision": 4, "explanation": "Per VDE 0855-300 any existing building earthing system may be used for antenna earthing — you do not need a separate electrode or special BNetzA approval. Using the common building earth actually improves safety by keeping everything at one potential.", - "source": "https://50ohm.de/NE_blitzerdung.html", + "source": "https://50ohm.de/NEA_blitzerdung.html#EK209", "confidence": 8 }, "EK210": { - "revision": 2, + "revision": 3, "explanation": "VDE 0855-300 expects a robust solid earthing conductor; the example minimum cross-sections are $16\\ \\text{mm}^2$ copper, $25\\ \\text{mm}^2$ aluminium, or $50\\ \\text{mm}^2$ steel. The larger sections for aluminium and steel compensate for their poorer conductivity, so they can carry a lightning surge without melting.", - "source": "https://50ohm.de/NE_blitzerdung.html", + "source": "https://50ohm.de/NEA_blitzerdung.html#EK210", "confidence": 8 }, "EK211": { - "revision": 2, + "revision": 3, "explanation": "Tying an antenna mast into a building's lightning-protection system alters that system, so it may only be done if a qualified lightning-protection specialist provides for it in the lightning-protection concept (Blitzschutzkonzept). It is neither always mandatory nor always forbidden — it depends on that professional assessment.", - "source": "https://50ohm.de/NE_blitzerdung.html", + "source": "https://50ohm.de/NEA_blitzerdung.html#EK211", "confidence": 8 }, "NA101": { - "revision": 2, + "revision": 3, "explanation": "Cutting at $2/3$ of 20 m gives a $13.33$ m piece; the remaining $1/3$ is $6.67$ m.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "source": "https://50ohm.de/NEA_erste_schritte.html#NA101", "confidence": 8 }, "NA102": { - "revision": 1, + "revision": 2, "explanation": "The maximum count is the whole-number quotient: $250/18.5 = 13.5$, so only 13 complete antennas fit before the remaining wire is too short.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "source": "https://50ohm.de/NEA_erste_schritte.html#NA102", "confidence": 8 }, "NA103": { - "revision": 1, + "revision": 2, "explanation": "Mass scales linearly with length for the same wire: $55/210$ of 100 m is about 26.2 m.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "source": "https://50ohm.de/NEA_erste_schritte.html#NA103", "confidence": 8 }, "NA201": { - "revision": 1, - "explanation": "Electric potential difference is measured in volts; amperes measure current, ohms resistance, and ampere-hours charge capacity.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "revision": 2, + "explanation": "Electric potential difference is measured in volts; amperes measure current, ohms resistance, and ampere-hours charge capacity. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannung.html#NA201", "confidence": 8 }, "NA202": { - "revision": 1, - "explanation": "Electric current is the rate of flow of charge, and the SI unit for current is the ampere.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "revision": 2, + "explanation": "Electric current is the rate of flow of charge, and the SI unit for current is the ampere. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_strom.html#NA202", "confidence": 8 }, "NA203": { - "revision": 1, - "explanation": "Electrical resistance is measured in ohms, the unit that relates voltage and current through Ohm's law.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "revision": 2, + "explanation": "Electrical resistance is measured in ohms, the unit that relates voltage and current through Ohm's law. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ohmsches_gesetz.html#NA203", "confidence": 8 }, "NA204": { - "revision": 1, + "revision": 2, "explanation": "Electrical power is measured in watts; joule is energy, kilowatt-hour is energy, and ampere-hour is charge capacity.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "source": "https://50ohm.de/NEA_leistung.html#NA204", "confidence": 8 }, "NA205": { - "revision": 1, + "revision": 2, "explanation": "Wavelength is a length, so it is normally expressed in metres rather than hertz or seconds.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "source": "https://50ohm.de/NEA_wellenlaenge.html#NA205", "confidence": 8 }, "NA206": { - "revision": 1, + "revision": 2, "explanation": "Frequency is cycles per second, and the named SI unit for that is hertz.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "source": "https://50ohm.de/NEA_frequenz.html#NA206", "confidence": 8 }, "NA207": { - "revision": 1, - "explanation": "One hertz means one cycle per second, so dimensionally $Hz = 1/s$.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "revision": 2, + "explanation": "One hertz means one cycle per second, so dimensionally $Hz = 1/s$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenz.html#NA207", "confidence": 8 }, "NA208": { - "revision": 1, - "explanation": "Milli means $10^{-3}$, so one volt is 1000 millivolts and 4.2 V is 4200 mV.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "revision": 3, + "explanation": "Milli means $10^{-3}$, so one volt is 1000 millivolts and 4.2 V is 4200 mV. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannung.html#NA208", "confidence": 8 }, "NA209": { - "revision": 1, - "explanation": "Milli means $10^{-3}$; therefore 42 mA is $42/1000$ A, or 0.042 A.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "revision": 3, + "explanation": "Milli means $10^{-3}$; therefore 42 mA is $42/1000$ A, or 0.042 A. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_strom.html#NA209", "confidence": 8 }, "NA210": { - "revision": 1, - "explanation": "Milli means one thousandth, so one watt contains 1000 milliwatts.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "revision": 3, + "explanation": "Milli means one thousandth, so one watt contains 1000 milliwatts. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung.html#NA210", "confidence": 8 }, "NA211": { - "revision": 2, - "explanation": "$0.010\\,\\mathrm{W} \\cdot 1000\\,\\mathrm{mW/W} = 10\\,\\mathrm{mW}$.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "revision": 4, + "explanation": "$0.010\\,\\mathrm{W} \\cdot 1000\\,\\mathrm{mW/W} = 10\\,\\mathrm{mW}$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung.html#NA211", "confidence": 8 }, "NA212": { - "revision": 1, - "explanation": "Mega means $10^6$; $144000000$ Hz divided by $10^6$ is 144 MHz.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "revision": 3, + "explanation": "Mega means $10^6$; $144000000$ Hz divided by $10^6$ is 144 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_frequenz.html#NA212", "confidence": 8 }, "NA213": { - "revision": 1, + "revision": 2, "explanation": "145000000 periods per second is 145000000 Hz, which is 145 MHz after dividing by $10^6$.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "source": "https://50ohm.de/NEA_amplitude_periode.html#NA213", "confidence": 8 }, "NB101": { - "revision": 2, + "revision": 3, "explanation": "Among the listed metals, copper has the lowest resistivity at room temperature, so it has the highest conductivity in that group.", - "source": "https://50ohm.de/N_leiter_nichtleiter.html", + "source": "https://50ohm.de/NEA_leiter_nichtleiter.html#NB101", "confidence": 7 }, "NB102": { - "revision": 2, + "revision": 3, "explanation": "Silver has even lower resistivity than copper, gold or tin at room temperature, so it is the best conductor in this list.", - "source": "https://50ohm.de/N_leiter_nichtleiter.html", + "source": "https://50ohm.de/NEA_leiter_nichtleiter.html#NB102", "confidence": 7 }, "NB103": { - "revision": 2, + "revision": 3, "explanation": "Tin has higher resistivity than copper, gold and aluminium, so it is the poorest conductor among the listed metals.", - "source": "https://50ohm.de/N_leiter_nichtleiter.html", + "source": "https://50ohm.de/NEA_leiter_nichtleiter.html#NB103", "confidence": 7 }, "NB104": { - "revision": 2, + "revision": 3, "explanation": "Porcelain and the plastics PE and PS are insulating materials; the other options include metals such as tungsten, brass or bronze.", - "source": "https://50ohm.de/N_leiter_nichtleiter.html", + "source": "https://50ohm.de/NEA_leiter_nichtleiter.html#NB104", "confidence": 7 }, "NB201": { - "revision": 1, + "revision": 2, "explanation": "The alternating long and short parallel plates are the conventional schematic symbol for a battery or cell stack.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_batterien_und_akkus.html#NB201", "confidence": 7 }, "NB202": { - "revision": 1, + "revision": 2, "explanation": "The shown reference symbol marks circuit ground or chassis reference, not an active source or switch.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_bauelemente.html#NB202", "confidence": 7 }, "NB203": { - "revision": 1, + "revision": 2, "explanation": "In a battery symbol the longer plate denotes the positive terminal and the shorter plate denotes the negative terminal.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_batterien_und_akkus.html#NB203", "confidence": 7 }, "NB204": { - "revision": 2, - "explanation": "Series-connected cells add their voltages; six 1.5 V cells give $6 \\cdot 1.5 V = 9 V$.", - "source": "https://50ohm.de/N_batterien_und_akkus.html", + "revision": 4, + "explanation": "Series-connected cells add their voltages; six 1.5 V cells give $6 \\cdot 1.5 V = 9 V$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_batterien_und_akkus.html#NB204", "confidence": 8 }, "NB205": { - "revision": 2, - "explanation": "The voltmeter is connected across two 1.5 V cells in series, so it reads their sum: 3 V.", - "source": "https://50ohm.de/N_spannungsmessung.html", + "revision": 4, + "explanation": "The voltmeter is connected across two 1.5 V cells in series, so it reads their sum: 3 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsmessung.html#NB205", "confidence": 7 }, "NB206": { - "revision": 2, - "explanation": "Both meter leads are on points with the same potential in the shown circuit, so the potential difference is 0 V.", - "source": "https://50ohm.de/N_spannungsmessung.html", + "revision": 4, + "explanation": "Both meter leads are on points with the same potential in the shown circuit, so the potential difference is 0 V. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_spannungsmessung.html#NB206", "confidence": 7 }, "NB207": { - "revision": 2, + "revision": 3, "explanation": "Current needs a complete closed loop through a source and load; the shown connection alone does not close a usable circuit.", - "source": "https://50ohm.de/N_slide_n_bauteile_und_schaltkreise.html", + "source": "https://50ohm.de/NEA_stromkreis.html#NB207", "confidence": 7 }, "NB301": { - "revision": 1, + "revision": 2, "explanation": "Electromagnetic waves in free space travel at the speed of light, about $3 \\cdot 10^8$ m/s or 300000 km/s.", - "source": "https://www.bipm.org/en/publications/si-brochure", + "source": "https://50ohm.de/NEA_funkwellen.html#NB301", "confidence": 8 }, "NB302": { - "revision": 2, - "explanation": "Use $f = c/\\lambda$: $300000000 / 2.08$ is about 144 MHz.", - "source": "https://50ohm.de/N_wellenlaenge.html", + "revision": 3, + "explanation": "Use $f = c/\\lambda$: $300000000 / 2.08$ is about 144 MHz. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wellenlaenge.html#NB302", "confidence": 8 }, "NB303": { - "revision": 2, - "explanation": "Use $\\lambda = c/f$: $300000000 / 433500000$ is about 0.69 m.", - "source": "https://50ohm.de/N_wellenlaenge.html", + "revision": 3, + "explanation": "Use $\\lambda = c/f$: $300000000 / 433500000$ is about 0.69 m. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_wellenlaenge.html#NB303", "confidence": 8 }, "NB304": { - "revision": 2, + "revision": 3, "explanation": "Radio waves are transverse, so the receiving antenna should match the electric-field orientation; mismatched polarisation causes avoidable loss.", - "source": "https://50ohm.de/NEA_polarisation.html", + "source": "https://50ohm.de/NEA_polarisation.html#NB304", "confidence": 7 }, "NB401": { - "revision": 2, + "revision": 3, "explanation": "A sinusoidal AC waveform is the smooth periodic curve with equal positive and negative half cycles shown in the correct figure.", - "source": "https://50ohm.de/N_sinusschwingung.html", + "source": "https://50ohm.de/NEA_sinusschwingung.html#NB401", "confidence": 7 }, "NB402": { - "revision": 2, + "revision": 3, "explanation": "Amplitude is the maximum displacement from the centre line; marker 1 points to that vertical height.", - "source": "https://50ohm.de/N_wellenlaenge.html", + "source": "https://50ohm.de/NEA_funkwellen.html#NB402", "confidence": 7 }, "NB403": { - "revision": 2, + "revision": 3, "explanation": "Wavelength is the spatial distance for one complete cycle, which is what marker 2 spans in the wave snapshot.", - "source": "https://50ohm.de/N_wellenlaenge.html", + "source": "https://50ohm.de/NEA_wellenlaenge.html#NB403", "confidence": 7 }, "NB404": { - "revision": 2, + "revision": 3, "explanation": "On an oscilloscope trace, amplitude is the vertical distance from the reference level to a peak; marker 1 indicates that height.", - "source": "https://50ohm.de/N_sinusschwingung.html", + "source": "https://50ohm.de/NEA_amplitude_periode.html#NB404", "confidence": 7 }, "NB405": { - "revision": 2, + "revision": 3, "explanation": "Period is the time for one complete cycle, so the horizontal interval marked 2 is one period.", - "source": "https://50ohm.de/N_sinusschwingung.html", + "source": "https://50ohm.de/NEA_amplitude_periode.html#NB405", "confidence": 7 }, "NB501": { - "revision": 1, - "explanation": "Ohm's law relates voltage, current and resistance as $U = R \\cdot I$.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "revision": 2, + "explanation": "Ohm's law relates voltage, current and resistance as $U = R \\cdot I$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ohmsches_gesetz.html#NB501", "confidence": 8 }, "NB502": { - "revision": 1, - "explanation": "Rearranging Ohm's law gives current as voltage divided by resistance: $I = U/R$.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "revision": 2, + "explanation": "Rearranging Ohm's law gives current as voltage divided by resistance: $I = U/R$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ohmsches_gesetz.html#NB502", "confidence": 8 }, "NB503": { - "revision": 1, - "explanation": "Rearranging $U = R \\cdot I$ for resistance gives $R = U/I$.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "revision": 2, + "explanation": "Rearranging $U = R \\cdot I$ for resistance gives $R = U/I$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ohmsches_gesetz.html#NB503", "confidence": 8 }, "NB504": { - "revision": 1, - "explanation": "Using Ohm's law with the shown resistance, $U = R \\cdot I$ gives 9.000 V for 90 mA.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "revision": 3, + "explanation": "Using Ohm's law with the shown resistance, $U = R \\cdot I$ gives 9.000 V for 90 mA. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_ohmsches_gesetz.html#NB504", "confidence": 8 }, "NB505": { - "revision": 1, + "revision": 2, "explanation": "Resistance is found from $R = U/I$; applying the voltage and current shown in the figure gives 40 ohm.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "source": "https://50ohm.de/NEA_ohmsches_gesetz.html#NB505", "confidence": 7 }, "NB601": { - "revision": 1, - "explanation": "DC input power is $P = U \\cdot I$, so $13.8 V \\cdot 1.5 A = 20.7 W$.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "revision": 3, + "explanation": "DC input power is $P = U \\cdot I$, so $13.8 V \\cdot 1.5 A = 20.7 W$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung.html#NB601", "confidence": 8 }, "NB602": { - "revision": 1, - "explanation": "Power converted to heat is $P = U \\cdot I$; 50 V times 0.050 A gives 2.5 W.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "revision": 3, + "explanation": "Power converted to heat is $P = U \\cdot I$; 50 V times 0.050 A gives 2.5 W. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung.html#NB602", "confidence": 8 }, "NB603": { - "revision": 1, - "explanation": "20 mA is 0.020 A, and $3.2 V \\cdot 0.020 A = 0.064 W = 64.0 mW$.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "revision": 3, + "explanation": "20 mA is 0.020 A, and $3.2 V \\cdot 0.020 A = 0.064 W = 64.0 mW$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung.html#NB603", "confidence": 8 }, "NB604": { - "revision": 1, - "explanation": "From $P = U \\cdot I$, current is $I = P/U = 100 W / 12 V = 8.33 A$.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "revision": 3, + "explanation": "From $P = U \\cdot I$, current is $I = P/U = 100 W / 12 V = 8.33 A$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung.html#NB604", "confidence": 8 }, "NB605": { - "revision": 1, - "explanation": "A 3 W load at 12 V draws $I = P/U = 3/12 = 0.25 A$, which is 250 mA.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "revision": 3, + "explanation": "A 3 W load at 12 V draws $I = P/U = 3/12 = 0.25 A$, which is 250 mA. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung.html#NB605", "confidence": 8 }, "NB606": { - "revision": 1, - "explanation": "A 48 W load at 12 V draws $I = P/U = 48/12 = 4 A$.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "revision": 3, + "explanation": "A 48 W load at 12 V draws $I = P/U = 48/12 = 4 A$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_leistung.html#NB606", "confidence": 8 }, "NB701": { - "revision": 1, + "revision": 2, "explanation": "The open contact in the shown schematic is the conventional symbol for a switch.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_stromkreis.html#NB701", "confidence": 7 }, "NB702": { - "revision": 1, + "revision": 2, "explanation": "Technical current direction is defined from the positive terminal through the external circuit toward the negative terminal.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "source": "https://50ohm.de/NEA_stromkreis.html#NB702", "confidence": 7 }, "NB703": { - "revision": 2, + "revision": 3, "explanation": "An LED lights only when the circuit is closed and the diode is forward-biased with current flowing through it.", - "source": "https://50ohm.de/N_slide_n_bauteile_und_schaltkreise.html", + "source": "https://50ohm.de/NEA_halbleiter.html#NB703", "confidence": 7 }, "NC101": { - "revision": 1, + "revision": 2, "explanation": "The zig-zag or rectangular two-terminal schematic element is the conventional resistor symbol.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_stromkreis.html#NC101", "confidence": 7 }, "NC102": { - "revision": 1, + "revision": 2, "explanation": "In the resistor colour code, green as the multiplier band means $10^5$, or 100000.", - "source": "IEC 60062 marking codes for resistors and capacitors", + "source": "https://50ohm.de/NEA_widerstandsfarbcode.html#NC102", "confidence": 8 }, "NC103": { - "revision": 1, + "revision": 2, "explanation": "For 1.2 kOhm, the first two digits are 1 and 2, brown and red, and the multiplier is $10^2$, red.", - "source": "IEC 60062 marking codes for resistors and capacitors", + "source": "https://50ohm.de/NEA_widerstandsfarbcode.html#NC103", "confidence": 8 }, "NC104": { - "revision": 1, + "revision": 2, "explanation": "Red and violet give the digits 2 and 7; a red multiplier is $10^2$, so the value is $27 \\cdot 100 = 2700$ ohm, or 2.7 kOhm.", - "source": "IEC 60062 marking codes for resistors and capacitors", + "source": "https://50ohm.de/NEA_widerstandsfarbcode.html#NC104", "confidence": 8 }, "NC105": { - "revision": 1, + "revision": 2, "explanation": "Yellow and violet give 4 and 7; a red multiplier is $10^2$, so the value is 4700 ohm or 4.7 kOhm.", - "source": "IEC 60062 marking codes for resistors and capacitors", + "source": "https://50ohm.de/NEA_widerstandsfarbcode.html#NC105", "confidence": 8 }, "NC106": { - "revision": 1, + "revision": 2, "explanation": "Red and violet give 27; an orange multiplier is $10^3$, so the value is 27000 ohm or 27 kOhm.", - "source": "IEC 60062 marking codes for resistors and capacitors", + "source": "https://50ohm.de/NEA_widerstandsfarbcode.html#NC106", "confidence": 8 }, "NC107": { - "revision": 1, + "revision": 2, "explanation": "Yellow and violet give 47; an orange multiplier is $10^3$, so the value is 47000 ohm or 47 kOhm.", - "source": "IEC 60062 marking codes for resistors and capacitors", + "source": "https://50ohm.de/NEA_widerstandsfarbcode.html#NC107", "confidence": 8 }, "NC108": { - "revision": 1, - "explanation": "In the resistor tolerance colour code, silver denotes a tolerance of plus or minus 10 percent.", - "source": "IEC 60062 marking codes for resistors and capacitors", + "revision": 2, + "explanation": "In the resistor tolerance colour code, silver denotes a tolerance of plus or minus 10 percent. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_widerstandsfarbcode.html#NC108", "confidence": 8 }, "NC109": { - "revision": 1, - "explanation": "In the resistor tolerance colour code, gold denotes a tolerance of plus or minus 5 percent.", - "source": "IEC 60062 marking codes for resistors and capacitors", + "revision": 2, + "explanation": "In the resistor tolerance colour code, gold denotes a tolerance of plus or minus 5 percent. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_widerstandsfarbcode.html#NC109", "confidence": 8 }, "NC110": { - "revision": 1, - "explanation": "In the resistor tolerance colour code, brown denotes a tolerance of plus or minus 1 percent.", - "source": "IEC 60062 marking codes for resistors and capacitors", + "revision": 2, + "explanation": "In the resistor tolerance colour code, brown denotes a tolerance of plus or minus 1 percent. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_widerstandsfarbcode.html#NC110", "confidence": 8 }, "NC201": { - "revision": 1, + "revision": 2, "explanation": "Two separated plates in the schematic symbol represent a capacitor, because a capacitor stores charge between two conductors.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_bauelemente.html#NC201", "confidence": 7 }, "NC301": { - "revision": 1, + "revision": 2, "explanation": "The looped or coiled schematic element is the conventional symbol for an inductor or coil.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_bauelemente.html#NC301", "confidence": 7 }, "NC401": { - "revision": 1, + "revision": 2, "explanation": "A diode symbol shows a one-way junction; current flows conventionally from anode toward cathode when forward-biased.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_halbleiter.html#NC401", "confidence": 7 }, "NC402": { - "revision": 1, + "revision": 2, "explanation": "A light-emitting diode is drawn as a diode with arrows showing emitted light.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_halbleiter.html#NC402", "confidence": 7 }, "NC403": { - "revision": 1, + "revision": 2, "explanation": "The diode terminal at the triangle side is the anode, and the terminal at the bar side is the cathode.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_halbleiter.html#NC403", "confidence": 7 }, "NC404": { - "revision": 2, + "revision": 3, "explanation": "Current flows through a diode circuit only when the diode is forward-biased and the loop is closed.", - "source": "https://50ohm.de/N_slide_n_bauteile_und_schaltkreise.html", + "source": "https://50ohm.de/NEA_halbleiter.html#NC404", "confidence": 7 }, "NC501": { - "revision": 1, + "revision": 2, "explanation": "A transistor symbol has three terminals for controlling current through the device, unlike two-terminal passive components.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_bauelemente.html#NC501", "confidence": 7 }, "ND101": { - "revision": 2, + "revision": 3, "explanation": "A mains power supply converts 230 V AC from the wall outlet into the DC voltage a mobile transceiver needs.", - "source": "https://50ohm.de/N_netzgeraet_1.html", + "source": "https://50ohm.de/NEA_netzgeraet_1.html#ND101", "confidence": 7 }, "ND102": { - "revision": 3, - "explanation": "Mobile amateur transceivers are normally designed for vehicle electrical systems, so an external supply is usually around 13.8 V DC.", - "source": "https://50ohm.de/N_netzgeraet_1.html", + "revision": 5, + "explanation": "Mobile amateur transceivers are normally designed for vehicle electrical systems, so an external supply is usually around 13.8 V DC. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_netzgeraet_1.html#ND102", "confidence": 7 }, "ND103": { - "revision": 2, + "revision": 3, "explanation": "A complete DC circuit needs an outgoing and a return conductor, so current leaves through one lead and returns through the other.", - "source": "https://50ohm.de/N_netzgeraet_1.html", + "source": "https://50ohm.de/NEA_netzgeraet_1.html#ND103", "confidence": 7 }, "ND104": { - "revision": 2, + "revision": 3, "explanation": "The two conductors complete the current path through the transceiver; without the return lead the circuit is open.", - "source": "https://50ohm.de/N_netzgeraet_1.html", + "source": "https://50ohm.de/NEA_netzgeraet_1.html#ND104", "confidence": 7 }, "ND105": { - "revision": 3, + "revision": 4, "explanation": "DC equipment conventionally marks the positive lead red and the negative lead black to reduce polarity mistakes.", - "source": "https://50ohm.de/N_netzgeraet_1.html", + "source": "https://50ohm.de/NEA_netzgeraet_1.html#ND105", "confidence": 7 }, "ND106": { - "revision": 3, + "revision": 4, "explanation": "Transceivers are polarity-sensitive DC loads, so reversing plus and minus can put voltage on the wrong internal circuitry.", - "source": "https://50ohm.de/N_netzgeraet_1.html", + "source": "https://50ohm.de/NEA_netzgeraet_1.html#ND106", "confidence": 7 }, "ND107": { - "revision": 3, + "revision": 4, "explanation": "Reverse polarity can drive current through protection parts or semiconductor junctions in the wrong direction and damage the radio.", - "source": "https://50ohm.de/N_netzgeraet_1.html", + "source": "https://50ohm.de/NEA_netzgeraet_1.html#ND107", "confidence": 7 }, "ND108": { - "revision": 3, + "revision": 4, "explanation": "Current limiting protects against short circuits, and thermal shutdown protects the supply when internal heating becomes excessive.", - "source": "https://50ohm.de/N_netzgeraet_1.html", + "source": "https://50ohm.de/NEA_netzgeraet_1.html#ND108", "confidence": 7 }, "ND109": { - "revision": 2, + "revision": 3, "explanation": "The protective contact connects exposed conductive parts to the protective-earth conductor so fault current can be carried safely away.", - "source": "https://publikationen.dguv.de/regelwerk/dguv-informationen/284/sicherheit-bei-arbeiten-an-elektrischen-anlagen", + "source": "https://50ohm.de/NEA_netzgeraet_1.html#ND109", "confidence": 8 }, "ND110": { - "revision": 2, + "revision": 3, "explanation": "A short circuit can make batteries or accumulators deliver very high current, causing heat, fire risk or cell damage.", - "source": "https://publikationen.dguv.de/regelwerk/dguv-informationen/284/sicherheit-bei-arbeiten-an-elektrischen-anlagen", + "source": "https://50ohm.de/NEA_batterien_und_akkus.html#ND110", "confidence": 7 }, "ND201": { - "revision": 1, + "revision": 2, "explanation": "An oscillator is a circuit that generates a periodic electrical signal without needing an external signal of that frequency.", - "source": "IEC 60050 International Electrotechnical Vocabulary", + "source": "https://50ohm.de/NEA_frequenz.html#ND201", "confidence": 7 }, "NE101": { - "revision": 2, + "revision": 3, "explanation": "Modulation varies a carrier in a controlled way so information can be transported by the radio-frequency signal.", - "source": "https://50ohm.de/N_rauch_und_morsezeichen.html", + "source": "https://50ohm.de/NEA_rauch_und_morsezeichen.html#NE101", "confidence": 7 }, "NE102": { - "revision": 2, + "revision": 3, "explanation": "SSB, FM and AM are all modulation methods; the distractors mix in bands, equipment names or operating procedures.", - "source": "https://50ohm.de/NE_trxmodulation.html", + "source": "https://50ohm.de/NEA_trxmodulation.html#NE102", "confidence": 7 }, "NE201": { - "revision": 2, + "revision": 3, "explanation": "CW conveys information by keying a continuous RF carrier on and off, which forms the Morse elements.", - "source": "https://50ohm.de/N_rauch_und_morsezeichen.html", + "source": "https://50ohm.de/NEA_rauch_und_morsezeichen.html#NE201", "confidence": 7 }, "NE202": { - "revision": 2, + "revision": 3, "explanation": "In amplitude modulation, the carrier amplitude follows the information signal while the carrier frequency ideally stays fixed.", - "source": "https://50ohm.de/NE_am.html", + "source": "https://50ohm.de/NEA_am.html#NE202", "confidence": 7 }, "NE203": { - "revision": 2, + "revision": 3, "explanation": "Ordinary AM transmits a carrier plus both sidebands; SSB suppresses the carrier and one sideband to save bandwidth and power.", - "source": "https://50ohm.de/NE_ssb.html", + "source": "https://50ohm.de/NEA_ssb.html#NE203", "confidence": 7 }, "NE204": { - "revision": 2, + "revision": 3, "explanation": "LSB and USB are the lower and upper sideband versions of SSB; both suppress the carrier but keep opposite sides of the spectrum.", - "source": "https://50ohm.de/NE_ssb.html", + "source": "https://50ohm.de/NEA_ssb.html#NE204", "confidence": 7 }, "NE205": { - "revision": 2, + "revision": 3, "explanation": "In an AM spectrum, the lower sideband lies below the carrier and the upper sideband lies above it.", - "source": "https://50ohm.de/NE_ssb.html", + "source": "https://50ohm.de/NEA_ssb.html#NE205", "confidence": 7 }, "NE206": { - "revision": 2, + "revision": 3, "explanation": "AM produces two mirror sidebands around the carrier, so the correct spectrum contains both LSB and USB for the audio content.", - "source": "https://50ohm.de/NE_am.html", + "source": "https://50ohm.de/NEA_am.html#NE206", "confidence": 7 }, "NE207": { - "revision": 2, + "revision": 3, "explanation": "USB keeps the sideband above the carrier, with audio-frequency components translated upward in frequency.", - "source": "https://50ohm.de/NE_ssb.html", + "source": "https://50ohm.de/NEA_ssb.html#NE207", "confidence": 7 }, "NE208": { - "revision": 2, + "revision": 3, "explanation": "LSB keeps the sideband below the carrier, so the audio spectrum appears on the lower-frequency side.", - "source": "https://50ohm.de/NE_ssb.html", + "source": "https://50ohm.de/NEA_ssb.html#NE208", "confidence": 7 }, "NE209": { - "revision": 2, + "revision": 3, "explanation": "USB is the upper-sideband mode of SSB, meaning the receiver demodulates only the sideband above the suppressed carrier frequency.", - "source": "https://50ohm.de/NE_trxmodulation.html", + "source": "https://50ohm.de/NEA_trxmodulation.html#NE209", "confidence": 7 }, "NE210": { - "revision": 2, + "revision": 3, "explanation": "The 2 m amateur SSB convention uses upper sideband, so the transceiver mode must be USB.", - "source": "https://50ohm.de/NE_trxmodulation.html", + "source": "https://50ohm.de/NEA_trxmodulation.html#NE210", "confidence": 7 }, "NE211": { - "revision": 2, + "revision": 3, "explanation": "On 80 m, amateur SSB voice conventionally uses lower sideband, so the receiver mode is LSB.", - "source": "https://50ohm.de/NE_trxmodulation.html", + "source": "https://50ohm.de/NEA_trxmodulation.html#NE211", "confidence": 7 }, "NE212": { - "revision": 2, + "revision": 3, "explanation": "SSB speech depends on the correct sideband and precise tuning; checking sideband mode and tuning the VFO addresses both causes.", - "source": "https://50ohm.de/NE_trxmodulation.html", + "source": "https://50ohm.de/NEA_trxmodulation.html#NE212", "confidence": 7 }, "NE301": { - "revision": 2, + "revision": 3, "explanation": "In frequency modulation, the information signal varies the carrier frequency while the carrier amplitude ideally remains constant.", - "source": "https://50ohm.de/NEA_fm.html", + "source": "https://50ohm.de/NEA_fm.html#NE301", "confidence": 7 }, "NE302": { - "revision": 2, + "revision": 3, "explanation": "FM is defined by varying a carrier's frequency according to the signal being transmitted.", - "source": "https://50ohm.de/NEA_fm.html", + "source": "https://50ohm.de/NEA_fm.html#NE302", "confidence": 7 }, "NE303": { - "revision": 3, + "revision": 4, "explanation": "FM information is carried by frequency deviation, German Hub/Frequenzhub: the carrier swings above and below its centre frequency. The RF amplitude is ideally unaffected by microphone audio.", - "source": "https://50ohm.de/NEA_fm.html", + "source": "https://50ohm.de/NEA_fm.html#NE303", "confidence": 7 }, "NE304": { - "revision": 3, + "revision": 4, "explanation": "In ideal FM the transmitter output power is essentially constant. Speaking louder increases frequency deviation, German Hub/Frequenzhub, but it does not increase the set RF carrier power.", - "source": "https://50ohm.de/NEA_fm.html", + "source": "https://50ohm.de/NEA_fm.html#NE304", "confidence": 7 }, "NE305": { - "revision": 2, - "explanation": "A 15 kHz-wide emission extends about half its bandwidth on each side of the centre frequency, so it needs at least 7.5 kHz clearance.", - "source": "https://50ohm.de/NE_bandbreite.html", + "revision": 4, + "explanation": "A 15 kHz-wide emission extends about half its bandwidth on each side of the centre frequency, so it needs at least 7.5 kHz clearance. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_bandbreite.html#NE305", "confidence": 7 }, "NE306": { - "revision": 3, + "revision": 4, "explanation": "Hub or Frequenzhub means FM frequency deviation: the carrier's maximum swing away from its centre frequency. Too much deviation usually comes from excessive audio level, so speaking more quietly reduces the Hub and narrows the FM signal.", - "source": "https://50ohm.de/NEA_fm.html", + "source": "https://50ohm.de/NEA_fm.html#NE306", "confidence": 8 }, "NE307": { - "revision": 2, + "revision": 3, "explanation": "Handheld VHF/UHF amateur radios commonly support analogue FM and digital voice systems such as DMR and D-STAR.", - "source": "https://50ohm.de/N_digital_voice.html", + "source": "https://50ohm.de/NEA_digital_voice.html#NE307", "confidence": 7 }, "NE308": { - "revision": 2, + "revision": 3, "explanation": "Voice repeaters on VHF/UHF commonly carry analogue FM and digital voice modes such as DMR and D-STAR.", - "source": "https://50ohm.de/N_relaisfunkstellen.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#NE308", "confidence": 7 }, "NE309": { - "revision": 2, + "revision": 3, "explanation": "Analogue amateur voice repeaters on VHF/UHF conventionally use FM because it is robust for local line-of-sight voice links.", - "source": "https://50ohm.de/N_relaisfunkstellen.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#NE309", "confidence": 7 }, "NE310": { - "revision": 2, + "revision": 3, "explanation": "An FM receiver cannot cleanly demodulate two equal-strength co-channel signals at once, so simultaneous relay input signals interfere badly.", - "source": "https://50ohm.de/N_relaisfunkstellen.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#NE310", "confidence": 7 }, "NE401": { - "revision": 2, + "revision": 3, "explanation": "Digital text modes only interoperate when both stations use the same waveform and parameters such as speed, tone spacing or protocol settings.", - "source": "https://50ohm.de/N_funkfernschreiben.html", + "source": "https://50ohm.de/NEA_funkfernschreiben.html#NE401", "confidence": 7 }, "NE402": { - "revision": 2, + "revision": 3, "explanation": "Digital voice repeater networks need more than frequency and mode; routing parameters such as reflector, time slot or colour code select the intended network path.", - "source": "https://50ohm.de/N_digital_voice.html", + "source": "https://50ohm.de/NEA_digital_voice.html#NE402", "confidence": 7 }, "NE403": { - "revision": 2, + "revision": 3, "explanation": "Time-division systems carry separate conversations in alternating time slots, allowing more than one channel on the same RF frequency.", - "source": "https://50ohm.de/N_digital_voice.html", + "source": "https://50ohm.de/NEA_digital_voice.html#NE403", "confidence": 7 }, "NE404": { - "revision": 2, + "revision": 3, "explanation": "DMR, D-STAR, C4FM, M17 and FreeDV are amateur digital voice systems, unlike analogue-only or non-voice modes.", - "source": "https://50ohm.de/N_digital_voice.html", + "source": "https://50ohm.de/NEA_digital_voice.html#NE404", "confidence": 7 }, "NE405": { - "revision": 2, + "revision": 3, "explanation": "Link paths are fixed radio links used as infrastructure, for example to connect repeaters with each other or to HAMNET nodes.", - "source": "https://50ohm.de/N_slide_n_amateurfunkstationen.html", + "source": "https://50ohm.de/NEA_linkstrecken.html#NE405", "confidence": 7 }, "NF101": { - "revision": 2, + "revision": 3, "explanation": "SWR indication reports the antenna matching condition during transmit, so display item 1 is the SWR meter.", - "source": "https://50ohm.de/N_swr.html", + "source": "https://50ohm.de/NEA_swr.html#NF101", "confidence": 7 }, "NF102": { - "revision": 2, + "revision": 3, "explanation": "In transmit mode, a power meter display shows the RF output power being delivered by the transceiver.", - "source": "https://50ohm.de/N_ausgangsleistung.html", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#NF102", "confidence": 7 }, "NF103": { - "revision": 2, + "revision": 3, "explanation": "An S-meter indicates received signal strength, so it is the relevant receive-level display.", - "source": "https://50ohm.de/N_slide_n_erste_schritte.html", + "source": "https://50ohm.de/NEA_rst.html#NF103", "confidence": 7 }, "NF104": { - "revision": 2, + "revision": 3, "explanation": "An amplitude spectrum shows signal strength versus frequency, which matches display item 3.", - "source": "https://50ohm.de/N_wasserfall.html", + "source": "https://50ohm.de/NEA_wasserfall.html#NF104", "confidence": 7 }, "NF105": { - "revision": 2, + "revision": 3, "explanation": "A waterfall diagram adds time to the spectrum display, with newer signal traces appearing as coloured or bright lines.", - "source": "https://50ohm.de/N_wasserfall.html", + "source": "https://50ohm.de/NEA_wasserfall.html#NF105", "confidence": 7 }, "NF106": { - "revision": 2, + "revision": 3, "explanation": "A waterfall plot uses one axis for frequency, one for time, and colour or brightness for received signal strength.", - "source": "https://50ohm.de/N_wasserfall.html", + "source": "https://50ohm.de/NEA_wasserfall.html#NF106", "confidence": 7 }, "NF107": { - "revision": 2, + "revision": 3, "explanation": "A mismatched or missing load reflects RF power back toward the transmitter, which can overheat or damage the final amplifier.", - "source": "https://50ohm.de/N_dummy_load_1.html", + "source": "https://50ohm.de/NEA_dummy_load_1.html#NF107", "confidence": 7 }, "NF108": { - "revision": 2, + "revision": 3, "explanation": "PTT means push-to-talk: pressing the microphone switch keys the transmitter.", - "source": "https://50ohm.de/N_erste_schritte.html", + "source": "https://50ohm.de/NEA_erste_schritte.html#NF108", "confidence": 7 }, "NF109": { - "revision": 2, + "revision": 3, "explanation": "VOX is voice-operated transmit control, where microphone audio automatically keys the transmitter.", - "source": "https://50ohm.de/N_slide_n_transceiver.html", + "source": "https://50ohm.de/NEA_vox.html#NF109", "confidence": 7 }, "NF110": { - "revision": 2, + "revision": 3, "explanation": "If VOX is enabled, room noise or microphone audio can key the transmitter without pressing PTT.", - "source": "https://50ohm.de/N_slide_n_transceiver.html", + "source": "https://50ohm.de/NEA_vox.html#NF110", "confidence": 7 }, "NF111": { - "revision": 2, + "revision": 3, "explanation": "RIT changes only the receive frequency, letting you clarify the other station without moving your transmit frequency.", - "source": "https://50ohm.de/NE_rit.html", + "source": "https://50ohm.de/NEA_rit.html#NF111", "confidence": 7 }, "NF112": { - "revision": 2, + "revision": 3, "explanation": "With RIT active, receive and transmit can be offset; the operator may tune reception while transmitting on a slightly different frequency.", - "source": "https://50ohm.de/NE_rit.html", + "source": "https://50ohm.de/NEA_rit.html#NF112", "confidence": 7 }, "NF113": { - "revision": 2, + "revision": 3, "explanation": "Using different uplink and downlink bands makes filtering easier because the satellite can separate its receiver and transmitter signals more effectively.", - "source": "https://50ohm.de/N_slide_n_amateurfunkstationen.html", + "source": "https://50ohm.de/NEA_satelliten.html#NF113", "confidence": 7 }, "NF114": { - "revision": 2, + "revision": 3, "explanation": "Digital modes need baseband audio or data between computer and radio, either by an audio/USB interface or by a modem that performs that conversion.", - "source": "https://50ohm.de/NE_computersteuerung.html", + "source": "https://50ohm.de/NEA_computersteuerung.html#NF114", "confidence": 7 }, "NF115": { - "revision": 2, + "revision": 3, "explanation": "A data connector bypasses audio shaping intended for speech, giving digital signals a cleaner path into or out of the FM transceiver.", - "source": "https://50ohm.de/NE_computersteuerung.html", + "source": "https://50ohm.de/NEA_computersteuerung.html#NF115", "confidence": 7 }, "NF116": { - "revision": 2, + "revision": 3, "explanation": "CAT control is a serial command interface used to read and set radio functions such as frequency, power and PTT from a computer.", - "source": "https://50ohm.de/NE_computersteuerung.html", + "source": "https://50ohm.de/NEA_computersteuerung.html#NF116", "confidence": 7 }, "NF117": { - "revision": 2, + "revision": 3, "explanation": "Computer control can assert PTT or change settings unexpectedly, so it can create unintended transmissions or safety hazards if not supervised.", - "source": "https://50ohm.de/NE_computersteuerung.html", + "source": "https://50ohm.de/NEA_computersteuerung.html#NF117", "confidence": 7 }, "NF118": { - "revision": 2, + "revision": 3, "explanation": "A digipeater is a digital relay: it receives packet data and retransmits it, possibly after updating fields such as routing information.", - "source": "https://50ohm.de/N_slide_n_amateurfunkstationen.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#NF118", "confidence": 7 }, "NF201": { - "revision": 2, + "revision": 3, "explanation": "The block diagram is a receiver because the signal path runs from antenna input through receiving stages toward audio or data output.", - "source": "https://50ohm.de/N_slide_n_transceiver.html", + "source": "https://50ohm.de/NEA_aufbau_empfaenger.html#NF201", "confidence": 7 }, "NF301": { - "revision": 2, + "revision": 3, "explanation": "The S-meter gives the operator a relative indication of received signal level.", - "source": "https://50ohm.de/N_slide_n_transceiver.html", + "source": "https://50ohm.de/NEA_rst.html#NF301", "confidence": 7 }, "NF302": { - "revision": 2, + "revision": 3, "explanation": "Squelch mutes the receiver audio until a signal exceeds the set threshold, hiding FM noise when no useful signal is present.", - "source": "https://50ohm.de/N_slide_n_transceiver.html", + "source": "https://50ohm.de/NEA_squelch.html#NF302", "confidence": 7 }, "NF303": { - "revision": 2, + "revision": 3, "explanation": "Receiver sensitivity describes how weak a signal the receiver can still detect or demodulate usefully.", - "source": "https://50ohm.de/N_slide_n_transceiver.html", + "source": "https://50ohm.de/NEA_aufbau_empfaenger.html#NF303", "confidence": 7 }, "NF401": { - "revision": 2, + "revision": 3, "explanation": "The block diagram is a transmitter because the signal path builds an RF signal and delivers it toward the antenna output.", - "source": "https://50ohm.de/N_slide_n_transceiver.html", + "source": "https://50ohm.de/NEA_aufbau_sender.html#NF401", "confidence": 7 }, "NF402": { - "revision": 2, + "revision": 3, "explanation": "A simple transmitter generates RF, combines it with modulation, filters unwanted products, and amplifies the wanted signal.", - "source": "https://50ohm.de/N_slide_n_transceiver.html", + "source": "https://50ohm.de/NEA_aufbau_sender.html#NF402", "confidence": 7 }, "NF403": { - "revision": 2, + "revision": 3, "explanation": "The stages follow the usual transmitter chain: audio amplification, mixing with an RF oscillator, filtering, RF amplification, and final filtering.", - "source": "https://50ohm.de/N_slide_n_transceiver.html", + "source": "https://50ohm.de/NEA_aufbau_sender.html#NF403", "confidence": 7 }, "NF404": { - "revision": 2, + "revision": 3, "explanation": "A transmitter output filter should pass the wanted VHF band while attenuating unwanted frequencies outside it.", - "source": "https://50ohm.de/NE_slide_ne_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_1.html#NF404", "confidence": 7 }, "NG101": { - "revision": 1, + "revision": 2, "explanation": "The shown schematic symbol represents an antenna connection, the point where RF energy is radiated or received.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_antennen.html#NG101", "confidence": 7 }, "NG102": { - "revision": 1, + "revision": 2, "explanation": "The ground symbol marks an earth connection or earth reference in the antenna diagram.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_rundstrahler.html#NG102", "confidence": 7 }, "NG103": { - "revision": 2, + "revision": 3, "explanation": "A dipole has two arms fed near the centre, which is the configuration shown.", - "source": "https://50ohm.de/N_dipol.html", + "source": "https://50ohm.de/NEA_dipol.html#NG103", "confidence": 7 }, "NG104": { - "revision": 2, - "explanation": "A Marconi antenna is a quarter-wave vertical worked against earth or a counterpoise, so it is a $\\lambda/4$ vertical antenna.", - "source": "https://50ohm.de/N_rundstrahler.html", + "revision": 3, + "explanation": "A Marconi antenna is a quarter-wave vertical worked against earth or a counterpoise, so it is a $\\lambda/4$ vertical antenna. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_rundstrahler.html#NG104", "confidence": 7 }, "NG105": { - "revision": 2, + "revision": 3, "explanation": "A ground-plane antenna is a vertical radiator with radial conductors forming the counterpoise, matching the shown structure.", - "source": "https://50ohm.de/N_rundstrahler.html", + "source": "https://50ohm.de/NEA_rundstrahler.html#NG105", "confidence": 7 }, "NG106": { - "revision": 2, + "revision": 3, "explanation": "The conductors that provide the counterpoise for a ground-plane antenna are called radials.", - "source": "https://50ohm.de/N_rundstrahler.html", + "source": "https://50ohm.de/NEA_rundstrahler.html#NG106", "confidence": 7 }, "NG107": { - "revision": 2, + "revision": 3, "explanation": "An end-fed antenna is fed at one end rather than at the centre, which matches the depicted arrangement.", - "source": "https://50ohm.de/N_endgespeiste_antennen.html", + "source": "https://50ohm.de/NEA_endgespeiste_antennen.html#NG107", "confidence": 7 }, "NG108": { - "revision": 2, + "revision": 3, "explanation": "A Yagi-Uda antenna uses a driven element with parasitic reflector and director elements on a boom, matching the shown directional antenna.", - "source": "https://50ohm.de/N_yagi_uda_1.html", + "source": "https://50ohm.de/NEA_yagi_uda_1.html#NG108", "confidence": 7 }, "NG109": { - "revision": 2, + "revision": 3, "explanation": "Long-wire antennas are practical mainly on HF; at VHF/UHF their physical size and radiation behaviour make other antenna types usual.", - "source": "https://50ohm.de/N_endgespeiste_antennen.html", + "source": "https://50ohm.de/NEA_endgespeiste_antennen.html#NG109", "confidence": 7 }, "NG110": { - "revision": 2, + "revision": 3, "explanation": "For a local round with stations in several directions, an omnidirectional antenna avoids aiming a directional beam at each station.", - "source": "https://50ohm.de/N_rundstrahler.html", + "source": "https://50ohm.de/NEA_rundstrahler.html#NG110", "confidence": 7 }, "NG111": { - "revision": 2, + "revision": 3, "explanation": "Repeaters around the station may lie in many directions, so a roof-mounted omnidirectional antenna gives broad azimuth coverage and height.", - "source": "https://50ohm.de/N_rundstrahler.html", + "source": "https://50ohm.de/NEA_rundstrahler.html#NG111", "confidence": 7 }, "NG201": { - "revision": 2, + "revision": 3, "explanation": "Common coaxial cable impedances include 50 ohm for transmitting systems and 75 ohm for receiving or video systems; 60 ohm also exists historically.", - "source": "https://50ohm.de/N_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen.html#NG201", "confidence": 7 }, "NG202": { - "revision": 3, + "revision": 4, "explanation": "The drawing shows the PL connector pair: a large knurled screw coupling and matching external thread. 50ohm notes that PL is also called a UHF connector, despite not being well suited for the UHF range.", - "source": "https://50ohm.de/N_steckverbinder_pl.html", + "source": "https://50ohm.de/NEA_steckverbinder_pl.html#NG202", "confidence": 8 }, "NG203": { - "revision": 3, + "revision": 4, "explanation": "The drawing shows the BNC connector system. Its distinguishing feature is the bayonet lock: the connector is inserted and then turned about 90 degrees instead of being screwed on like PL or N.", - "source": "https://50ohm.de/N_steckverbinder_bnc.html", + "source": "https://50ohm.de/NEA_steckverbinder_bnc.html#NG203", "confidence": 8 }, "NG204": { - "revision": 3, + "revision": 4, "explanation": "The drawing shows an N connector pair. 50ohm describes N connectors as higher-quality threaded connectors used into the gigahertz range; the spring contacts around the centre pin are characteristic.", - "source": "https://50ohm.de/N_steckverbinder_n.html", + "source": "https://50ohm.de/NEA_steckverbinder_n.html#NG204", "confidence": 8 }, "NG205": { - "revision": 3, + "revision": 4, "explanation": "The drawing shows SMA connectors: a small threaded connector system with a hexagonal coupling nut. 50ohm emphasizes their small size and suitability for very high frequencies.", - "source": "https://50ohm.de/N_steckverbinder_sma.html", + "source": "https://50ohm.de/NEA_steckverbinder_sma.html#NG205", "confidence": 8 }, "NG206": { - "revision": 3, + "revision": 4, "explanation": "For frequencies above 300 MHz, the suitable connector systems in the answer set are N and SMA. 50ohm summarizes this directly: N and SMA connector systems are best suited for high and very high frequencies.", - "source": "https://50ohm.de/N_steckverbinder_sma.html", + "source": "https://50ohm.de/NEA_steckverbinder_sma.html#NG206", "confidence": 8 }, "NG207": { - "revision": 2, + "revision": 3, "explanation": "Coaxial-line attenuation accumulates with length and generally rises with frequency, so both matter when choosing VHF/UHF feed line.", - "source": "https://50ohm.de/N_uebertragungsleitungen.html", + "source": "https://50ohm.de/NEA_uebertragungsleitungen.html#NG207", "confidence": 7 }, "NG208": { - "revision": 2, + "revision": 3, "explanation": "Extra coax adds loss in both forward and reflected waves, so the meter can show a lower SWR even though efficiency has worsened.", - "source": "https://50ohm.de/N_swr.html", + "source": "https://50ohm.de/NEA_swr.html#NG208", "confidence": 7 }, "NG301": { - "revision": 2, - "explanation": "An SWR of 1:1 means no reflected power from mismatch, which is the best possible match.", - "source": "https://50ohm.de/N_swr.html", + "revision": 3, + "explanation": "An SWR of 1:1 means no reflected power from mismatch, which is the best possible match. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_swr.html#NG301", "confidence": 8 }, "NG302": { - "revision": 2, + "revision": 3, "explanation": "A high SWR-meter indication means significant reflected power, which points to poor antenna or feed-line matching.", - "source": "https://50ohm.de/N_swr.html", + "source": "https://50ohm.de/NEA_swr.html#NG302", "confidence": 7 }, "NG303": { - "revision": 2, + "revision": 3, "explanation": "Mismatch or damage changes the line impedance seen by the transmitter, causing RF reflections and therefore a higher SWR.", - "source": "https://50ohm.de/N_swr.html", + "source": "https://50ohm.de/NEA_swr.html#NG303", "confidence": 7 }, "NG304": { - "revision": 2, + "revision": 3, "explanation": "A dipole that resonates too low is electrically too long; shortening both arms raises its resonant frequency.", - "source": "https://50ohm.de/N_slide_n_antennen_und_leitungen.html", + "source": "https://50ohm.de/NEA_dipol.html#NG304", "confidence": 8 }, "NG305": { - "revision": 2, + "revision": 3, "explanation": "A dipole that resonates too high is electrically too short; lengthening both arms lowers its resonant frequency.", - "source": "https://50ohm.de/N_slide_n_antennen_und_leitungen.html", + "source": "https://50ohm.de/NEA_dipol.html#NG305", "confidence": 8 }, "NG401": { - "revision": 2, + "revision": 3, "explanation": "ERP is radiated power referenced to a half-wave dipole, not to an isotropic radiator.", - "source": "https://life.itu.int/radioclub/rr/art1.pdf", + "source": "https://50ohm.de/NEA_effektive_strahlungsleistung_erp_1.html#NG401", "confidence": 8 }, "NG402": { - "revision": 2, + "revision": 3, "explanation": "EIRP is radiated power referenced to an ideal isotropic radiator.", - "source": "https://life.itu.int/radioclub/rr/art1.pdf", + "source": "https://50ohm.de/NEA_aequivalente_isotrope_strahlungsleistung_eirp_1.html#NG402", "confidence": 8 }, "NH101": { - "revision": 2, + "revision": 3, "explanation": "The ionosphere is the ionised upper-atmosphere region that can refract HF radio waves back toward Earth.", - "source": "https://50ohm.de/NEA_ionosphaere.html", + "source": "https://50ohm.de/NEA_ionosphaere.html#NH101", "confidence": 7 }, "NH102": { - "revision": 2, + "revision": 3, "explanation": "Free electrons and ions in the ionosphere change the refractive index for radio waves, allowing HF waves to bend rather than travel straight into space.", - "source": "https://50ohm.de/NEA_ionosphaere.html", + "source": "https://50ohm.de/NEA_ionosphaere.html#NH102", "confidence": 7 }, "NH201": { - "revision": 2, + "revision": 3, "explanation": "Solar activity controls ionisation density in the ionosphere, and the roughly eleven-year solar cycle therefore strongly affects HF propagation.", - "source": "https://50ohm.de/NEA_ionosphaere.html", + "source": "https://50ohm.de/NEA_ionosphaere.html#NH201", "confidence": 7 }, "NH301": { - "revision": 2, + "revision": 3, "explanation": "Standard atmospheric refraction bends VHF paths slightly toward Earth, making the radio horizon about 15 percent beyond the geometric horizon.", - "source": "https://50ohm.de/N_funkhorizont.html", + "source": "https://50ohm.de/NEA_funkhorizont.html#NH301", "confidence": 7 }, "NH302": { - "revision": 2, + "revision": 3, "explanation": "VHF coverage is largely line-of-sight; raising the antenna increases the visible radio path over terrain and curvature.", - "source": "https://50ohm.de/N_funkhorizont.html", + "source": "https://50ohm.de/NEA_funkhorizont.html#NH302", "confidence": 7 }, "NH303": { - "revision": 2, - "explanation": "The best VHF path is the station with the clearest quasi-optical path in the terrain profile; in the shown figure that is $\\text{E}_3$.", - "source": "https://50ohm.de/N_funkhorizont.html", + "revision": 3, + "explanation": "The best VHF path is the station with the clearest quasi-optical path in the terrain profile; in the shown figure that is $\\text{E}_3$. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_funkhorizont.html#NH303", "confidence": 7 }, "NH304": { - "revision": 2, + "revision": 3, "explanation": "Tropospheric inversions can form ducts or enhanced refractive layers, allowing VHF signals to travel hundreds of kilometres beyond normal range.", - "source": "https://50ohm.de/N_troposphaere.html", + "source": "https://50ohm.de/NEA_troposphaere.html#NH304", "confidence": 7 }, "NH305": { - "revision": 2, + "revision": 3, "explanation": "Sporadic-E uses dense temporary ionisation patches in the E region, typically around 100 to 110 km altitude.", - "source": "https://50ohm.de/NEA_sporadic_e_1.html", + "source": "https://50ohm.de/NEA_sporadic_e_1.html#NH305", "confidence": 7 }, "NH306": { - "revision": 2, + "revision": 3, "explanation": "On 2 m, Sporadic-E means unusually long VHF paths via refraction in sporadic E-region ionisation, often around 1000 to 2000 km.", - "source": "https://50ohm.de/NEA_sporadic_e_1.html", + "source": "https://50ohm.de/NEA_sporadic_e_1.html#NH306", "confidence": 7 }, "NI101": { - "revision": 1, + "revision": 2, "explanation": "The voltmeter symbol identifies a voltage-measuring instrument, which is connected across the points whose potential difference is measured.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_spannungsmessung.html#NI101", "confidence": 7 }, "NI102": { - "revision": 1, + "revision": 2, "explanation": "The ammeter symbol identifies a current-measuring instrument, which is inserted in series with the current path.", - "source": "IEC 60617 graphical symbols for diagrams", + "source": "https://50ohm.de/NEA_strommessung.html#NI102", "confidence": 7 }, "NI103": { - "revision": 2, + "revision": 3, "explanation": "Voltage is measured in parallel with the battery, so the meter must be connected across the battery while the circuit remains operating.", - "source": "https://50ohm.de/N_spannungsmessung.html", + "source": "https://50ohm.de/NEA_spannungsmessung.html#NI103", "confidence": 7 }, "NI104": { - "revision": 2, + "revision": 3, "explanation": "Current through a component is measured in series, so the meter must be inserted into the path through the resistor and LED.", - "source": "https://50ohm.de/N_spannungsmessung.html", + "source": "https://50ohm.de/NEA_strommessung.html#NI104", "confidence": 7 }, "NI201": { - "revision": 2, + "revision": 3, "explanation": "A standing-wave meter compares forward and reflected RF power, which is how antenna matching is inferred.", - "source": "https://50ohm.de/N_swr.html", + "source": "https://50ohm.de/NEA_swr.html#NI201", "confidence": 7 }, "NI202": { - "revision": 2, + "revision": 3, "explanation": "To measure reflections in the antenna system, the SWR meter is inserted between the transceiver and antenna, with the transmitter on the other port.", - "source": "https://50ohm.de/N_swr.html", + "source": "https://50ohm.de/NEA_swr.html#NI202", "confidence": 7 }, "NI203": { - "revision": 2, - "explanation": "An ideal match has no reflected wave, so the SWR meter should read 1:1.", - "source": "https://50ohm.de/N_swr.html", + "revision": 3, + "explanation": "An ideal match has no reflected wave, so the SWR meter should read 1:1. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_swr.html#NI203", "confidence": 8 }, "NI301": { - "revision": 2, + "revision": 3, "explanation": "A frequency counter measures the frequency of an electrical signal directly, so it is the appropriate instrument for transmitter frequency.", - "source": "https://50ohm.de/N_frequenz.html", + "source": "https://50ohm.de/NEA_frequenz.html#NI301", "confidence": 7 }, "NI401": { - "revision": 2, + "revision": 3, "explanation": "An oscillogram is time-domain display; an amplitude spectrum is frequency-domain display showing the signal components by frequency.", - "source": "https://50ohm.de/N_wasserfall.html", + "source": "https://50ohm.de/NEA_wasserfall.html#NI401", "confidence": 8 }, "NJ101": { - "revision": 2, + "revision": 3, "explanation": "Shielding confines RF currents and fields, reducing unwanted coupling into nearby equipment or wiring.", - "source": "https://50ohm.de/NE_elektromagnetische_vertraeglichkeit.html", + "source": "https://50ohm.de/NEA_elektromagnetische_vertraeglichkeit.html#NJ101", "confidence": 7 }, "NJ102": { - "revision": 2, + "revision": 3, "explanation": "Interference complaints should be handled cooperatively; arranging checks can identify whether the cause is the amateur station, the affected device or the installation.", - "source": "https://50ohm.de/NE_elektromagnetische_vertraeglichkeit.html", + "source": "https://50ohm.de/NEA_stoerungen_vermeiden.html#NJ102", "confidence": 7 }, "NJ201": { - "revision": 2, + "revision": 3, "explanation": "Unwanted emissions waste spectrum and may interfere with other services, so a transmitter must be adjusted and filtered to avoid them.", - "source": "https://50ohm.de/NE_slide_ne_sender.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_1.html#NJ201", "confidence": 7 }, "NJ202": { - "revision": 3, + "revision": 4, "explanation": "A dummy load provides a non-radiating matched load, letting you align the transmitter without putting test signals on the air.", - "source": "https://50ohm.de/N_dummy_load_1.html", + "source": "https://50ohm.de/NEA_dummy_load_1.html#NJ202", "confidence": 7 }, "NK101": { - "revision": 2, + "revision": 3, "explanation": "Shielding HF stages reduces radiation and susceptibility by keeping RF energy inside the intended circuit region.", - "source": "https://50ohm.de/NE_elektromagnetische_vertraeglichkeit.html", + "source": "https://50ohm.de/NEA_elektromagnetische_vertraeglichkeit.html#NK101", "confidence": 7 }, "NK102": { - "revision": 2, + "revision": 3, "explanation": "A good RF earth gives unwanted RF currents a controlled return path and reduces coupling into equipment, cables and surroundings.", - "source": "https://50ohm.de/NE_elektromagnetische_vertraeglichkeit.html", + "source": "https://50ohm.de/NEA_elektromagnetische_vertraeglichkeit.html#NK102", "confidence": 7 }, "NK201": { - "revision": 2, + "revision": 3, "explanation": "Near antennas, electromagnetic fields can exceed exposure limits; operators need enough knowledge to keep people outside unsafe field strengths.", - "source": "https://publikationen.dguv.de/regelwerk/dguv-informationen/284/sicherheit-bei-arbeiten-an-elektrischen-anlagen", + "source": "https://50ohm.de/NEA_personenschutzabstand.html#NK201", "confidence": 7 }, "NK301": { - "revision": 2, - "explanation": "Common electrical-safety practice treats contact above 50 V AC or 120 V DC as hazardous under normal dry conditions.", - "source": "https://publikationen.dguv.de/regelwerk/dguv-informationen/284/sicherheit-bei-arbeiten-an-elektrischen-anlagen", + "revision": 4, + "explanation": "Common electrical-safety practice treats contact above 50 V AC or 120 V DC as hazardous under normal dry conditions. Hilfsmittel: the formula needed here is printed in the Formelsammlung of the official exam aids (Hilfsmittel), so in the exam you apply it rather than recalling it from memory.", + "source": "https://50ohm.de/NEA_gefahren.html#NK301", "confidence": 8 }, "NK302": { - "revision": 2, + "revision": 3, "explanation": "The main electrical hazards are current through the body, arc faults, and secondary accidents such as falls caused by shock or startle.", - "source": "https://publikationen.dguv.de/regelwerk/dguv-informationen/284/sicherheit-bei-arbeiten-an-elektrischen-anlagen", + "source": "https://50ohm.de/NEA_gefahren.html#NK302", "confidence": 8 }, "NK303": { - "revision": 2, + "revision": 3, "explanation": "Body current can heat tissue, force muscles to contract, and disturb the heart rhythm, including dangerous fibrillation.", - "source": "https://publikationen.dguv.de/regelwerk/dguv-informationen/284/sicherheit-bei-arbeiten-an-elektrischen-anlagen", + "source": "https://50ohm.de/NEA_gefahren.html#NK303", "confidence": 8 }, "NK304": { - "revision": 2, + "revision": 3, "explanation": "Heart rhythm disturbances can be delayed after an electric shock, so medical assessment is required even when the person initially feels well.", - "source": "https://publikationen.dguv.de/regelwerk/dguv-informationen/284/sicherheit-bei-arbeiten-an-elektrischen-anlagen", + "source": "https://50ohm.de/NEA_gefahren.html#NK304", "confidence": 8 }, "NK305": { - "revision": 2, + "revision": 3, "explanation": "A fuse protects only as designed when its current rating and time-current characteristic match the original device.", - "source": "https://publikationen.dguv.de/regelwerk/dguv-informationen/284/sicherheit-bei-arbeiten-an-elektrischen-anlagen", + "source": "https://50ohm.de/NEA_netzgeraet_1.html#NK305", "confidence": 8 }, "NK306": { - "revision": 2, + "revision": 3, "explanation": "Rechargeable batteries can deliver high energy and contain reactive chemicals, so misuse can cause burns, chemical injury or toxic exposure.", - "source": "https://publikationen.dguv.de/regelwerk/dguv-informationen/284/sicherheit-bei-arbeiten-an-elektrischen-anlagen", + "source": "https://50ohm.de/NEA_batterien_und_akkus.html#NK306", "confidence": 7 }, "NK307": { - "revision": 2, + "revision": 3, "explanation": "A vehicle battery can supply very high short-circuit current; wrong connection can create arcs and ignite wiring or surrounding material.", - "source": "https://50ohm.de/NEA_einbau_kfz.html", + "source": "https://50ohm.de/NEA_einbau_kfz.html#NK307", "confidence": 7 }, "NK308": { - "revision": 2, + "revision": 3, "explanation": "Vehicle electronics and approval conditions depend on manufacturer installation limits, so those instructions govern radio installation.", - "source": "https://50ohm.de/NEA_einbau_kfz.html", + "source": "https://50ohm.de/NEA_einbau_kfz.html#NK308", "confidence": 7 }, "NK309": { - "revision": 2, + "revision": 3, "explanation": "Keeping coax away from vehicle wiring reduces RF coupling into control electronics and avoids parallel runs acting as coupled lines.", - "source": "https://50ohm.de/NEA_einbau_kfz.html", + "source": "https://50ohm.de/NEA_einbau_kfz.html#NK309", "confidence": 7 }, "NK310": { - "revision": 2, + "revision": 3, "explanation": "The centre of a metal roof gives a VHF mobile antenna a good ground plane and a more even radiation pattern around the car.", - "source": "https://50ohm.de/NEA_einbau_kfz.html", + "source": "https://50ohm.de/NEA_einbau_kfz.html#NK310", "confidence": 7 }, "NK311": { - "revision": 2, + "revision": 3, "explanation": "Antenna parts must be arranged so that failure cannot bring conductive parts into contact with power lines, where lethal voltages may be present.", - "source": "https://publikationen.dguv.de/regelwerk/dguv-informationen/284/sicherheit-bei-arbeiten-an-elektrischen-anlagen", + "source": "https://50ohm.de/NEA_antennen_energieleitungen.html#NK311", "confidence": 8 }, "VA101": { - "revision": 1, + "revision": 2, "explanation": "The international definition is in the ITU Radio Regulations, which define radio services globally before national rules implement them.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_amateurfunkdienst.html#VA101", "confidence": 9 }, "VA102": { - "revision": 2, + "revision": 3, "explanation": "The ITU definition gives the purpose of amateur radio: self-training, amateur-to-amateur communication and technical investigation. Memorise those three ideas; they explain many later non-commercial and open-traffic rules.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_amateurfunkdienst.html#VA102", "confidence": 9 }, "VA103": { - "revision": 2, + "revision": 3, "explanation": "Adding a satellite changes the path, not the purpose. Amateur-satellite service still serves self-training, intercommunication and technical investigation, just via space stations.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_amateurfunkdienst.html#VA103", "confidence": 9 }, "VA104": { - "revision": 2, + "revision": 3, "explanation": "The international rule already contains the amateur identity: authorised person, personal technical interest, no money motive. If an answer sounds commercial or unauthorised, it conflicts with that definition.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_funkamateur.html#VA104", "confidence": 9 }, "VA201": { - "revision": 1, + "revision": 2, "explanation": "In the RR, a station is the transmitters, receivers and accessories needed at one place to carry out a radiocommunication service.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_amateurfunkstelle.html#VA201", "confidence": 9 }, "VA202": { - "revision": 1, + "revision": 2, "explanation": "An amateur station is simply a station in the amateur service, so the service definition determines the station type.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_amateurfunkstelle.html#VA202", "confidence": 9 }, "VA301": { - "revision": 2, + "revision": 3, "explanation": "The Radio Regulations are the global baseline for all radio services. Amateur radio is not outside that system; special amateur rules sit inside the general RR framework.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_gesetze_vorschriften.html#VA301", "confidence": 9 }, "VA302": { - "revision": 2, + "revision": 3, "explanation": "International amateur traffic is for amateur-service content and personal remarks. The rule keeps amateur radio from becoming an international message or business service.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_amateurfunkstelle.html#VA302", "confidence": 9 }, "VA303": { - "revision": 2, + "revision": 3, "explanation": "The core idea is transparency: amateur messages are not secret traffic. The narrow exception is control signalling for satellites, where encryption protects the station rather than hiding a private conversation.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_satelliten.html#VA303", "confidence": 9 }, "VA304": { - "revision": 2, + "revision": 3, "explanation": "Morse is not globally forced by the RR anymore; each administration decides. For the exam, remember that Germany controls its own certificate requirements here.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_morsetelegrafie.html#VA304", "confidence": 9 }, "VA401": { - "revision": 2, + "revision": 3, "explanation": "ITU regions exist because the same frequency can have different allocations in different parts of the world. Always ask: which region's table applies?", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_itu_regionen.html#VA401", "confidence": 9 }, "VA402": { - "revision": 2, + "revision": 3, "explanation": "There are three ITU regions. This is pure table knowledge, but it anchors the later Europe/Americas/Asia-Pacific region questions.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_itu_regionen.html#VA402", "confidence": 9 }, "VA403": { - "revision": 2, + "revision": 3, "explanation": "Germany follows Region 1. Memory hook: Region 1 is Europe plus Africa and nearby western Asia; German band-plan questions start from that world region.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_itu_regionen.html#VA403", "confidence": 9 }, "VA404": { - "revision": 2, + "revision": 3, "explanation": "Canada is Region 2 because Region 2 is the Americas. Memory hook: Region 2 = the western hemisphere.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_itu_regionen.html#VA404", "confidence": 9 }, "VA405": { - "revision": 2, + "revision": 3, "explanation": "Australia is Region 3, the Asia-Pacific region. Memory hook: after Europe/Africa = 1 and Americas = 2, Australia lands in the remaining Asia-Pacific bucket.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_itu_regionen.html#VA405", "confidence": 9 }, "VA406": { - "revision": 2, + "revision": 3, "explanation": "Call-sign prefixes are not chosen casually by countries; they come from internationally allocated series. That is why a prefix can identify the country or administration behind a station.", - "source": "https://www.itu.int/gladapp/Allocation/CallSigns", + "source": "https://50ohm.de/NEA_rufzeichenaufbau.html#VA406", "confidence": 9 }, "VA407": { - "revision": 1, + "revision": 2, "explanation": "The Q code meanings are an ITU operating-code item, so the RR is the authoritative international reference.", - "source": "https://www.itu.int/pub/R-REG-RR", + "source": "https://50ohm.de/NEA_q_schluessel.html#VA407", "confidence": 8 }, "VB101": { - "revision": 2, + "revision": 3, "explanation": "The CEPT Novice certificate is proof of a recognised novice-level exam. It is mainly a portability document: it helps another administration map your German class E knowledge to its novice rules.", - "source": "https://docdb.cept.org/download/2768", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB101", "confidence": 9 }, "VB102": { - "revision": 2, + "revision": 3, "explanation": "HAREC is not the radio licence itself; it is the harmonised proof that you passed the full CEPT-level exam. German class A corresponds to that level.", - "source": "https://docdb.cept.org/download/2565", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB102", "confidence": 9 }, "VB103": { - "revision": 2, + "revision": 3, "explanation": "Use this memory model: HAREC proves exam level, the country issues the actual licence. It lets participating administrations recognise your class-A-level qualification.", - "source": "https://docdb.cept.org/download/2565", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB103", "confidence": 9 }, "VB104": { - "revision": 2, + "revision": 3, "explanation": "Separate the CEPT documents by job: T/R 61-01 = temporary visitor operation, T/R 61-02/HAREC = full exam proof, ERC Report 32 = novice exam topics, ECC (05)06 = novice visitor operation.", - "source": "https://docdb.cept.org/download/3321", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB104", "confidence": 8 }, "VB105": { - "revision": 3, + "revision": 4, "explanation": "Class N is national-only for this purpose. Memory hook: A travels with full CEPT, E can use CEPT Novice where implemented, N has no automatic CEPT travel privilege.", - "source": "https://50ohm.de/NEA_funken_im_ausland.html", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB105", "confidence": 8 }, "VB106": { - "revision": 2, + "revision": 3, "explanation": "CEPT Novice is not worldwide permission. It works only where the visited country implemented ECC (05)06, and only for temporary non-resident operation.", - "source": "https://docdb.cept.org/download/2768", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB106", "confidence": 9 }, "VB107": { - "revision": 2, + "revision": 3, "explanation": "Class A visitor operation relies on T/R 61-01. Memorise the two limits: the visited country must implement it, and the stay must be temporary rather than residence.", - "source": "https://docdb.cept.org/download/3321", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB107", "confidence": 9 }, "VB108": { - "revision": 2, + "revision": 3, "explanation": "CEPT documents can be accepted beyond CEPT countries if the country explicitly implements or recognises them. The deciding factor is the host country's acceptance, not geography alone.", - "source": "https://docdb.cept.org/download/3321", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB108", "confidence": 8 }, "VB109": { - "revision": 2, + "revision": 3, "explanation": "CEPT guest operation is for visits, not moving your licence abroad. The exam number to remember is up to three months for the normal temporary-stay case.", - "source": "https://docdb.cept.org/download/3321", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB109", "confidence": 9 }, "VB110": { - "revision": 2, + "revision": 3, "explanation": "In Germany, the prefix tells which CEPT route the visitor uses. Full CEPT visitors put DL/ before the home call; CEPT Novice visitors put DO/ before it.", - "source": "https://docdb.cept.org/download/3321", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB110", "confidence": 9 }, "VB111": { - "revision": 2, + "revision": 3, "explanation": "Do not carry German bands and power limits in your suitcase. CEPT gives a visitor shortcut, but the host country's implemented limits control actual operation.", - "source": "https://docdb.cept.org/download/3321", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB111", "confidence": 9 }, "VB112": { - "revision": 2, + "revision": 3, "explanation": "The 6 m trap is about host-country control. Even with a German licence, you may use 50 MHz abroad only if the visited country's CEPT implementation and national allocation allow it.", - "source": "https://docdb.cept.org/download/3321", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB112", "confidence": 9 }, "VB113": { - "revision": 2, + "revision": 3, "explanation": "If the country has not implemented the CEPT route, there is no automatic shortcut. Then you need that country's own guest authorisation before transmitting.", - "source": "https://docdb.cept.org/download/3321", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB113", "confidence": 9 }, "VB114": { - "revision": 2, + "revision": 3, "explanation": "CEPT visitor operation follows the individual operator, not a German club station as an institution. Moving club-station operation abroad needs separate permission.", - "source": "https://docdb.cept.org/download/3321", + "source": "https://50ohm.de/NEA_funken_im_ausland.html#VB114", "confidence": 8 }, "VC101": { - "revision": 2, + "revision": 3, "explanation": "The AFuG is the German statutory basis for who may participate in the amateur service and under what conditions.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__1.html", + "source": "https://50ohm.de/NEA_gesetze_vorschriften.html#VC101", "confidence": 10 }, "VC102": { - "revision": 1, + "revision": 2, "explanation": "AFuG §2 defines amateur radio as amateur-to-amateur communication plus experimentation, self-training, international understanding and support of relief actions.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__2.html", + "source": "https://50ohm.de/NEA_amateurfunkdienst.html#VC102", "confidence": 10 }, "VC103": { - "revision": 1, + "revision": 2, "explanation": "AFuG §2 defines an amateur station by its transmitters, receivers, antennas and required accessories, capable of operating on amateur frequencies.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__2.html", + "source": "https://50ohm.de/NEA_amateurfunkstelle.html#VC103", "confidence": 10 }, "VC104": { - "revision": 2, + "revision": 3, "explanation": "AFuG assigns the law's administrative tasks to the Bundesnetzagentur.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__10.html", + "source": "https://50ohm.de/NEA_gesetze_vorschriften.html#VC104", "confidence": 9 }, "VC105": { - "revision": 1, + "revision": 2, "explanation": "AFuG §2 defines a radio amateur as the holder of an amateur certificate or harmonised examination certificate.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__2.html", + "source": "https://50ohm.de/NEA_funkamateur.html#VC105", "confidence": 10 }, "VC106": { - "revision": 2, + "revision": 3, "explanation": "Think two steps: the exam proves knowledge, but the admission plus person-bound call sign is the legal permission to transmit. Certificate alone is not an on-air licence.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__3.html", + "source": "https://50ohm.de/NEA_zulassung.html#VC106", "confidence": 10 }, "VC107": { - "revision": 2, + "revision": 3, "explanation": "The admission follows the named person, not the radio equipment. If someone else transmits, they need their own authorisation rather than borrowing yours.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__3.html", + "source": "https://50ohm.de/NEA_persoenliche_rufzeichen.html#VC107", "confidence": 10 }, "VC108": { - "revision": 1, - "explanation": "AFuG §3 sets the exam/admission requirement but no minimum age requirement.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__3.html", + "revision": 3, + "explanation": "German amateur radio sets no minimum age: the law admits any natural person resident in Germany to the exam on application, so children can qualify once they pass.", + "source": "https://50ohm.de/NEA_zulassung.html#VC108", "confidence": 9 }, "VC109": { - "revision": 2, + "revision": 3, "explanation": "AFuG permits amateurs with assigned call signs to operate commercial, home-built or modified transmitters on amateur frequencies.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__5.html", + "source": "https://50ohm.de/NEA_recht_zum_selbstbau.html#VC109", "confidence": 9 }, "VC110": { - "revision": 1, + "revision": 2, "explanation": "AFuG rights attach to frequencies designated for the amateur service; transmitting outside those allocations is not covered.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__3.html", + "source": "https://50ohm.de/NEA_frequenzzuteilung.html#VC110", "confidence": 9 }, "VC111": { - "revision": 2, + "revision": 3, "explanation": "Amateur radio is not a public messaging service. The normal rule is amateur station to amateur station; emergency and disaster help is the narrow exception.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__5.html", + "source": "https://50ohm.de/NEA_nur_mit_afu_stellen.html#VC111", "confidence": 9 }, "VC112": { - "revision": 2, + "revision": 3, "explanation": "Third-party traffic is normally forbidden because amateur radio is for the amateur service, not carrying other people's messages. Memorise the exception: Not/Katastrophe turns the station into emergency support.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__5.html", + "source": "https://50ohm.de/NEA_nur_mit_afu_stellen.html#VC112", "confidence": 9 }, "VC113": { - "revision": 2, + "revision": 3, "explanation": "The law defines the amateur by personal interest in radio technique, not business interest. If the purpose is making money or serving a business, it stops fitting the amateur-service idea.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__2.html", + "source": "https://50ohm.de/NEA_funkamateur.html#VC113", "confidence": 10 }, "VC114": { - "revision": 2, + "revision": 3, "explanation": "Same memory hook as VC113: amateur radio is personal, experimental and non-commercial. A station may support hobby learning and emergency help, not commercial operations.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__5.html", + "source": "https://50ohm.de/NEA_gewerblich.html#VC114", "confidence": 9 }, "VC115": { - "revision": 1, + "revision": 2, "explanation": "Business provision of telecommunications services is outside the amateur service and is expressly not an amateur-station purpose.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__5.html", + "source": "https://50ohm.de/NEA_gewerblich.html#VC115", "confidence": 9 }, "VC116": { - "revision": 2, + "revision": 3, "explanation": "Your person-bound call sign is your legal on-air identity. Using someone else's person-bound call would hide who is actually responsible, so only your assigned call sign is allowed.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__3.html", + "source": "https://50ohm.de/NEA_rufzeichenaufbau.html#VC116", "confidence": 9 }, "VC117": { - "revision": 1, + "revision": 2, "explanation": "AFuG allows call signs to be changed for important reasons, especially when international requirements change.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__3.html", + "source": "https://50ohm.de/NEA_persoenliche_rufzeichen.html#VC117", "confidence": 9 }, "VC118": { - "revision": 2, + "revision": 3, "explanation": "AFuG requires amateur stations to meet EMC protection requirements so their operation remains compatible with other equipment.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__7.html", + "source": "https://50ohm.de/NEA_elektromagnetische_vertraeglichkeit.html#VC118", "confidence": 9 }, "VC119": { - "revision": 2, + "revision": 3, "explanation": "AFuG lets amateurs deviate from EMVG immunity requirements for their own station, meaning they choose their own station's immunity level.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__7.html", + "source": "https://50ohm.de/NEA_elektromagnetische_vertraeglichkeit.html#VC119", "confidence": 9 }, "VC120": { - "revision": 2, + "revision": 3, "explanation": "For self-built amateur equipment, AFuG allows the amateur to determine the station's immunity level instead of meeting ordinary EMVG immunity requirements.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__7.html", + "source": "https://50ohm.de/NEA_elektromagnetische_vertraeglichkeit.html#VC120", "confidence": 9 }, "VC121": { - "revision": 2, + "revision": 3, "explanation": "AFuG provides that BNetzA issues a site certificate on request; this is separate from the amateur-station display procedure.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__7.html", + "source": "https://50ohm.de/NEA_standortbescheinigung.html#VC121", "confidence": 9 }, "VC122": { - "revision": 2, + "revision": 3, "explanation": "AFuG and AFuV enforcement powers allow BNetzA to restrict operation or order an amateur station taken out of service after violations.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__11.html", + "source": "https://50ohm.de/NEA_verstoesse_und_folgen.html#VC122", "confidence": 9 }, "VC123": { - "revision": 1, + "revision": 2, "explanation": "Persistent violations can lead to revocation because the admission and call-sign assignment are administrative permissions tied to lawful operation.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__3.html", + "source": "https://50ohm.de/NEA_verstoesse_und_folgen.html#VC123", "confidence": 9 }, "VC124": { - "revision": 2, + "revision": 3, "explanation": "AFuG treats operating without admission/call sign, commercial telecom service, and unauthorised third-party message relay as fineable offences.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__9.html", + "source": "https://50ohm.de/NEA_verstoesse_und_folgen.html#VC124", "confidence": 9 }, "VC125": { - "revision": 2, + "revision": 3, "explanation": "An unlawful station operation can be pursued by BNetzA as an administrative offence with a monetary fine.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__9.html", + "source": "https://50ohm.de/NEA_verstoesse_und_folgen.html#VC125", "confidence": 9 }, "VD101": { - "revision": 1, + "revision": 2, "explanation": "AFuV §1 points to Anlage 1 for the usable frequency ranges and technical operating conditions by class.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__1.html", + "source": "https://50ohm.de/NEA_frequenzzuteilung.html#VD101", "confidence": 10 }, "VD102": { - "revision": 2, + "revision": 3, "explanation": "The licence gate is for transmitting, not listening. Receiving amateur transmissions is allowed without admission; putting RF on the air is the regulated act.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_erste_schritte.html#VD102", "confidence": 10 }, "VD103": { - "revision": 2, + "revision": 3, "explanation": "Amateur traffic must be publicly understandable so others and the regulator can monitor what is happening. Encryption whose purpose is hiding the content breaks that open-language rule.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_offene_sprache.html#VD103", "confidence": 10 }, "VD104": { - "revision": 2, + "revision": 3, "explanation": "The encryption exception is about controlling equipment, not private conversations. Memorise it as: hidden control bits may be okay; hidden message content is not.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_satelliten.html#VD104", "confidence": 10 }, "VD105": { - "revision": 2, + "revision": 3, "explanation": "MAYDAY/PAN PAN/SECURITE belong to maritime and aeronautical safety systems. Amateur stations must not imitate those signals because false or casual use would weaken real emergency procedures.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_notfunk.html#VD105", "confidence": 10 }, "VD106": { - "revision": 1, + "revision": 2, "explanation": "AFuV requires amateur stations to be installed and maintained according to generally recognised technical rules.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_aufbau_sender.html#VD106", "confidence": 10 }, "VD107": { - "revision": 1, + "revision": 2, "explanation": "AFuV lets BNetzA demand technical documents and an antenna layout sketch for a transmitting station.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VD107", "confidence": 10 }, "VD108": { - "revision": 2, + "revision": 3, "explanation": "BNetzA can ask for written operating records when it needs evidence, especially for interference or frequency-use questions. The point is traceability, not routine diary keeping.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__17.html", + "source": "https://50ohm.de/NEA_logbuch.html#VD108", "confidence": 10 }, "VD109": { - "revision": 2, + "revision": 3, "explanation": "A logbook is useful, but the exam rule is narrower: written operating records become mandatory when BNetzA demands them. Memorise: no general logbook duty, but comply on request.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__17.html", + "source": "https://50ohm.de/NEA_logbuch.html#VD109", "confidence": 10 }, "VD110": { - "revision": 1, + "revision": 2, "explanation": "AFuV requires unwanted emissions to be reduced to the lowest practicable level.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_unerwuenschte_aussendungen_1.html#VD110", "confidence": 10 }, "VD111": { - "revision": 1, + "revision": 2, "explanation": "During adjustment and measurement, AFuV requires effective measures to prevent free radiation of test signals.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_dummy_load_1.html#VD111", "confidence": 10 }, "VD112": { - "revision": 1, + "revision": 2, "explanation": "A carrier is normally not a valid transmission by itself, but a short unmodulated carrier can be necessary for tuning.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_dummy_load_1.html#VD112", "confidence": 9 }, "VD113": { - "revision": 1, + "revision": 2, "explanation": "AFuV requires name or address changes to be reported to BNetzA without undue delay.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__9.html", + "source": "https://50ohm.de/NEA_anschrift.html#VD113", "confidence": 10 }, "VD114": { - "revision": 1, + "revision": 2, "explanation": "AFuV §15 defines the call-sign list content: name, call sign and address unless publication of the address is opposed.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__15.html", + "source": "https://50ohm.de/NEA_anschrift.html#VD114", "confidence": 10 }, "VD115": { - "revision": 2, + "revision": 3, "explanation": "No BNetzA special permission is needed merely because the amateur station is operated in a watercraft or aircraft; other operator/vehicle permissions still matter.", - "source": "https://50ohm.de/NE_rufzeichenzusaetze.html", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#VD115", "confidence": 8 }, "VD116": { - "revision": 1, + "revision": 2, "explanation": "AFuV §16 allows BNetzA to grant temporary exceptions for special experimental and technical-scientific studies.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__16.html", + "source": "https://50ohm.de/NEA_experimentelle_studien.html#VD116", "confidence": 10 }, "VD117": { - "revision": 1, + "revision": 2, "explanation": "AFuV §2 defines a club station as a station used by at least three members of a group under a jointly used call sign.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__2.html", + "source": "https://50ohm.de/NEA_klubstationen.html#VD117", "confidence": 10 }, "VD118": { - "revision": 1, + "revision": 2, "explanation": "AFuV §2 defines a repeater as a remote or automatic amateur station that re-transmits or forwards received or stored content.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__2.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#VD118", "confidence": 10 }, "VD119": { - "revision": 1, + "revision": 2, "explanation": "AFuV §2 defines a beacon as an automatic amateur transmitting station that repeatedly emits signals for field-strength observations or reception tests.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__2.html", + "source": "https://50ohm.de/NEA_baken.html#VD119", "confidence": 10 }, "VD201": { - "revision": 1, + "revision": 2, "explanation": "AFuV §10 requires BNetzA to publish a German amateur call-sign plan that defines the call-sign formation rules.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__10.html", + "source": "https://50ohm.de/NEA_rufzeichenaufbau.html#VD201", "confidence": 10 }, "VD202": { - "revision": 1, + "revision": 2, "explanation": "AFuV §10 lists person-bound call signs and further call signs for training, remote/automatic stations and club stations.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__10.html", + "source": "https://50ohm.de/NEA_rufzeichenaufbau.html#VD202", "confidence": 10 }, "VD203": { - "revision": 1, + "revision": 2, "explanation": "The German call-sign plan uses a two-letter German prefix, one digit and usually a two- or three-letter suffix for person-bound call signs.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__10.html", + "source": "https://50ohm.de/NEA_rufzeichenaufbau.html#VD203", "confidence": 9 }, "VD204": { - "revision": 2, + "revision": 3, "explanation": "The call-sign plan permits special-event suffixes up to seven characters, including digits, provided the suffix ends with a letter.", - "source": "https://www.bundesnetzagentur.de/DE/Fachthemen/Telekommunikation/Frequenzen/SpezielleAnwendungen/Amateurfunk/DL_Vfg_AFu/Rufzeichenplan_10_24_Auszug_aus_Vfg_15_2025.pdf?__blob=publicationFile&v=4", + "source": "https://50ohm.de/NEA_besondere_anlaesse.html#VD204", "confidence": 8 }, "VD205": { - "revision": 2, + "revision": 3, "explanation": "The call sign is the station's accountability marker. Use the simple rhythm: identify at start, at end, and at least every 10 minutes while the contact continues.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__11.html", + "source": "https://50ohm.de/NEA_rufzeichen.html#VD205", "confidence": 10 }, "VD206": { - "revision": 1, + "revision": 2, "explanation": "BNetzA's call-sign-use rule points to the international spelling alphabet in RR Appendix 14 for identifying call signs.", - "source": "BNetzA Verfügung 13/2005; ITU RR Appendix 14", + "source": "https://50ohm.de/NEA_buchstabiertafel.html#VD206", "confidence": 8 }, "VD207": { - "revision": 1, + "revision": 2, "explanation": "The amateur call sign is the on-air identifier; it tells listeners which amateur station is transmitting.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__11.html", + "source": "https://50ohm.de/NEA_rufzeichen.html#VD207", "confidence": 10 }, "VD208": { - "revision": 1, + "revision": 2, "explanation": "AFuV §10 says there is no entitlement to a specific call sign.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__10.html", + "source": "https://50ohm.de/NEA_persoenliche_rufzeichen.html#VD208", "confidence": 10 }, "VD301": { - "revision": 2, + "revision": 3, "explanation": "Training operation exists so learners can get real operating practice before their own certificate. It is not a separate hobby privilege; it is exam preparation under a licensed trainer.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__12.html", + "source": "https://50ohm.de/NEA_ausbildungsrufzeichen.html#VD301", "confidence": 10 }, "VD302": { - "revision": 1, + "revision": 2, "explanation": "AFuV §12 permits training operation only for admitted class A or E amateurs.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__12.html", + "source": "https://50ohm.de/NEA_ausbildungsrufzeichen.html#VD302", "confidence": 10 }, "VD303": { - "revision": 2, + "revision": 3, "explanation": "A trainee may touch the microphone/key only because an authorised A or E amateur is directly instructing and supervising. Responsibility stays with the licensed trainer.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__12.html", + "source": "https://50ohm.de/NEA_ausbildungsfunk.html#VD303", "confidence": 10 }, "VD304": { - "revision": 2, + "revision": 3, "explanation": "Training does not create extra bands or power. The trainee operates inside the instructor's permission envelope, so memorise: trainer's class sets the limit.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__12.html", + "source": "https://50ohm.de/NEA_ausbildungsrufzeichen.html#VD304", "confidence": 10 }, "VD305": { - "revision": 1, + "revision": 2, "explanation": "AFuV §12 requires the instructor to provide BNetzA information about the type and extent of training operation on request.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__12.html", + "source": "https://50ohm.de/NEA_ausbildungsrufzeichen.html#VD305", "confidence": 10 }, "VD306": { - "revision": 2, + "revision": 3, "explanation": "The /T or /Trainee suffix tells listeners that the person operating is a trainee under supervision. It marks the trainee's transmission, not the instructor's ordinary operation.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__12.html", + "source": "https://50ohm.de/NEA_ausbildungsfunk.html#VD306", "confidence": 10 }, "VD401": { - "revision": 2, + "revision": 3, "explanation": "A club call sign still needs one accountable licensed person. The group leader names that responsible amateur so BNetzA knows who stands behind the station.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__14.html", + "source": "https://50ohm.de/NEA_klubstationen.html#VD401", "confidence": 10 }, "VD402": { - "revision": 1, + "revision": 2, "explanation": "AFuV §14 allows a club-station call sign only to a radio amateur already admitted to participate in the amateur service.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__14.html", + "source": "https://50ohm.de/NEA_klubstationen.html#VD402", "confidence": 10 }, "VD403": { - "revision": 1, + "revision": 2, "explanation": "AFuG §3 allows further call signs, including club-station call signs, only after the amateur has an admission and the additional assignment.", - "source": "https://www.gesetze-im-internet.de/afug_1997/__3.html", + "source": "https://50ohm.de/NEA_klubstationen.html#VD403", "confidence": 10 }, "VD404": { - "revision": 2, + "revision": 3, "explanation": "A club call sign is shared identification, not a licence substitute. To transmit with it, the operator still needs their own admission to the amateur service.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__14.html", + "source": "https://50ohm.de/NEA_klubstationen.html#VD404", "confidence": 10 }, "VD405": { - "revision": 1, + "revision": 2, "explanation": "AFuV permits admitted radio amateurs to operate at a club station even if they are not members of the group.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__14.html", + "source": "https://50ohm.de/NEA_klubstationen.html#VD405", "confidence": 10 }, "VD406": { - "revision": 2, + "revision": 3, "explanation": "A club-station call cannot upgrade the operator. If the operator's class and club call's class differ, use the lower privilege set: lowest class wins.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__14.html", + "source": "https://50ohm.de/NEA_klubstationen.html#VD406", "confidence": 10 }, "VD407": { - "revision": 2, + "revision": 3, "explanation": "AFuV Anlage 1 lists 7.000-7.200 MHz only in the class A column. A class A club-station call sign does not expand the operator's own licence privileges, so only class A operators may use 40 m there.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "source": "https://50ohm.de/NEA_klubstationen.html#VD407", "confidence": 10 }, "VD408": { - "revision": 1, + "revision": 2, "explanation": "AFuV does not require reporting short-term location changes of a club station, unlike permanent relevant assignment data changes.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__14.html", + "source": "https://50ohm.de/NEA_klubstationen.html#VD408", "confidence": 9 }, "VD501": { - "revision": 2, + "revision": 3, "explanation": "Repeaters and beacons transmit without a normal operator sitting at the controls, so they need their own separate call-sign assignment. Memorise: automatic station, separate call.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__13.html", + "source": "https://50ohm.de/NEA_fernbediente_automatische_stationen.html#VD501", "confidence": 10 }, "VD502": { - "revision": 1, + "revision": 2, "explanation": "A repeater may be operated only under its own assigned call sign and the site and operating conditions stated in that assignment.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__13.html", + "source": "https://50ohm.de/NEA_fernbediente_automatische_stationen.html#VD502", "confidence": 10 }, "VD503": { - "revision": 2, + "revision": 3, "explanation": "For repeaters above 30 MHz, the exam wants the table value: 50 W ERP. Treat it as a fixed repeater limit, separate from ordinary personal-station power limits.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#VD503", "confidence": 10 }, "VD504": { - "revision": 1, + "revision": 2, "explanation": "The responsible operator may exclude a user when that is necessary to keep the repeater operating without interference.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__13.html", + "source": "https://50ohm.de/NEA_relaisfunkstellen.html#VD504", "confidence": 9 }, "VD601": { - "revision": 2, + "revision": 3, "explanation": "Remote operation means the station is fixed and unattended locally, but the operator controls it from elsewhere, often over the internet. The key idea is distance plus ongoing control.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__2.html", + "source": "https://50ohm.de/NEA_remote_stationen.html#VD601", "confidence": 10 }, "VD602": { - "revision": 1, + "revision": 2, "explanation": "AFuV §13a links remote operation to a BNetzA notification by the remote-station operator.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__13a.html", + "source": "https://50ohm.de/NEA_remote_stationen.html#VD602", "confidence": 10 }, "VD603": { - "revision": 1, + "revision": 2, "explanation": "AFuV §13a restricts remote operation to holders of class A privileges.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__13a.html", + "source": "https://50ohm.de/NEA_remote_stationen.html#VD603", "confidence": 10 }, "VD604": { - "revision": 1, + "revision": 2, "explanation": "AFuV §13a allows class A club stations to be used for remote operation.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__13a.html", + "source": "https://50ohm.de/NEA_remote_stationen.html#VD604", "confidence": 10 }, "VD605": { - "revision": 2, + "revision": 3, "explanation": "Remote is not unattended free-running operation. The operator must still be able to control and stop the station indirectly, so operational safety remains their responsibility.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__2.html", + "source": "https://50ohm.de/NEA_remote_stationen.html#VD605", "confidence": 10 }, "VD606": { - "revision": 2, + "revision": 3, "explanation": "A remote station is powerful because anyone with access could transmit from it. The operator must gate access so only authorised amateurs can use it, preventing anonymous or abusive operation.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__13a.html", + "source": "https://50ohm.de/NEA_remote_stationen.html#VD606", "confidence": 10 }, "VD607": { - "revision": 1, + "revision": 2, "explanation": "AFuV §13a permits transmission through a remote station only by authorised amateurs with class A admission.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__13a.html", + "source": "https://50ohm.de/NEA_remote_stationen.html#VD607", "confidence": 10 }, "VD608": { - "revision": 1, + "revision": 2, "explanation": "BNetzA needs the operator's contact details so it can reach the responsible person quickly in case of radio interference.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__13a.html", + "source": "https://50ohm.de/NEA_remote_stationen.html#VD608", "confidence": 10 }, "VD609": { - "revision": 1, + "revision": 2, "explanation": "For a remotely operated club station, AFuV §13a limits access to members of the operating group.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/__13a.html", + "source": "https://50ohm.de/NEA_remote_stationen.html#VD609", "confidence": 10 }, "VD701": { - "revision": 2, - "explanation": "The Radio Regulations are the international framework, but you operate under German implementation. Memorise: RR may allow a band internationally; AFuV Anlage 1 tells you whether you may use it in Germany.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "The Radio Regulations are the international framework, but you operate under German implementation. Memorise: RR may allow a band internationally; AFuV Anlage 1 tells you whether you may use it in Germany. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_frequenzzuteilung.html#VD701", "confidence": 10 }, "VD702": { - "revision": 1, - "explanation": "AFuV Anlage 1 is the national table for German amateur frequency ranges and detailed usage conditions.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 is the national table for German amateur frequency ranges and detailed usage conditions. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_frequenzzuteilung.html#VD702", "confidence": 10 }, "VD703": { - "revision": 1, - "explanation": "CB radio is outside the amateur frequency allocations, so an amateur station is not authorised to transmit there.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "CB radio is outside the amateur frequency allocations, so an amateur station is not authorised to transmit there. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_nur_mit_afu_stellen.html#VD703", "confidence": 10 }, "VD704": { - "revision": 2, - "explanation": "Primary means priority user. A primary service may demand protection from secondary users, so secondary stations must move or stop if they cause trouble.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "Primary means priority user. A primary service may demand protection from secondary users, so secondary stations must move or stop if they cause trouble. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_primaerer_sekundaerer_funkdienst.html#VD704", "confidence": 10 }, "VD705": { - "revision": 2, - "explanation": "Secondary has the weaker position: do not interfere, and do not expect protection. Good memory hook: secondary means 'no trouble caused, no protection claimed'.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "Secondary has the weaker position: do not interfere, and do not expect protection. Good memory hook: secondary means 'no trouble caused, no protection claimed'. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_primaerer_sekundaerer_funkdienst.html#VD705", "confidence": 10 }, "VD706": { - "revision": 1, - "explanation": "AFuV Anlage 1 lists 7000-7200 kHz with primary status for the amateur service.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 lists 7000-7200 kHz with primary status for the amateur service. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_primaerer_sekundaerer_funkdienst.html#VD706", "confidence": 10 }, "VD707": { - "revision": 1, - "explanation": "A coastal station on its fixed assigned frequency cannot simply move; even in a shared primary band the amateur station must stop using that frequency unless a real emergency exists.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "A coastal station on its fixed assigned frequency cannot simply move; even in a shared primary band the amateur station must stop using that frequency unless a real emergency exists. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_primaerer_sekundaerer_funkdienst.html#VD707", "confidence": 9 }, "VD708": { - "revision": 1, - "explanation": "The 433.05-434.79 MHz ISM designation means non-communication industrial, scientific, medical, domestic or similar applications also use that range.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "The 433.05-434.79 MHz ISM designation means non-communication industrial, scientific, medical, domestic or similar applications also use that range. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_primaerer_sekundaerer_funkdienst.html#VD708", "confidence": 10 }, "VD709": { - "revision": 2, - "explanation": "This is the German 160 m band. Memorise it as the MF/low-HF entry: 1810-2000 kHz, just below the broadcast-style 2 MHz area.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the German 160 m band. Memorise it as the MF/low-HF entry: 1810-2000 kHz, just below the broadcast-style 2 MHz area. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD709", "confidence": 10 }, "VD710": { - "revision": 2, - "explanation": "This is the 80 m band. The exam table value is 3.5-3.8 MHz; remember it as the first classic HF band after 160 m.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 80 m band. The exam table value is 3.5-3.8 MHz; remember it as the first classic HF band after 160 m. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD710", "confidence": 10 }, "VD711": { - "revision": 2, - "explanation": "This is the 40 m band. The German amateur range is 7.0-7.2 MHz; the clean round 7 MHz start makes it easy to anchor.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 40 m band. The German amateur range is 7.0-7.2 MHz; the clean round 7 MHz start makes it easy to anchor. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD711", "confidence": 10 }, "VD712": { - "revision": 2, - "explanation": "This is the 30 m WARC band, and it is deliberately narrow: 10.100-10.150 MHz. Memory hook: 30 m is the tiny 50 kHz slice at 10.1 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 30 m WARC band, and it is deliberately narrow: 10.100-10.150 MHz. Memory hook: 30 m is the tiny 50 kHz slice at 10.1 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD712", "confidence": 10 }, "VD713": { - "revision": 2, - "explanation": "This is the 20 m band. The table value is 14.000-14.350 MHz; remember 14 MHz as the main long-distance HF anchor.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 20 m band. The table value is 14.000-14.350 MHz; remember 14 MHz as the main long-distance HF anchor. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD713", "confidence": 10 }, "VD714": { - "revision": 2, - "explanation": "This is the 17 m WARC band. Like the other WARC bands, it is narrow: 18.068-18.168 MHz, a 100 kHz slice.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 17 m WARC band. Like the other WARC bands, it is narrow: 18.068-18.168 MHz, a 100 kHz slice. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD714", "confidence": 10 }, "VD715": { - "revision": 2, - "explanation": "This is the 15 m band. The range starts cleanly at 21 MHz and runs to 21.45 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 15 m band. The range starts cleanly at 21 MHz and runs to 21.45 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD715", "confidence": 10 }, "VD716": { - "revision": 2, - "explanation": "This is the 12 m WARC band. Memory hook: another narrow 100 kHz WARC slice, 24.89-24.99 MHz, just below 25 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 12 m WARC band. Memory hook: another narrow 100 kHz WARC slice, 24.89-24.99 MHz, just below 25 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD716", "confidence": 10 }, "VD717": { - "revision": 2, - "explanation": "This is the 10 m band. It is the broad class-N HF band too: 28-29.7 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 10 m band. It is the broad class-N HF band too: 28-29.7 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD717", "confidence": 10 }, "VD718": { - "revision": 2, - "explanation": "This is the 6 m band in Germany: 50-52 MHz. Remember it as the bridge between HF-like propagation and VHF regulation.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 6 m band in Germany: 50-52 MHz. Remember it as the bridge between HF-like propagation and VHF regulation. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD718", "confidence": 10 }, "VD719": { - "revision": 2, - "explanation": "This is the 2 m VHF band. The exam value is compact and round: 144-146 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 2 m VHF band. The exam value is compact and round: 144-146 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD719", "confidence": 10 }, "VD720": { - "revision": 2, - "explanation": "This is the 70 cm UHF band. Memorise the German allocation as the round 10 MHz block from 430 to 440 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 70 cm UHF band. Memorise the German allocation as the round 10 MHz block from 430 to 440 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD720", "confidence": 10 }, "VD721": { - "revision": 2, - "explanation": "This is the 23 cm band. The German amateur range is 1240-1300 MHz; remember it as the first microwave-style exam range after 70 cm.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 23 cm band. The German amateur range is 1240-1300 MHz; remember it as the first microwave-style exam range after 70 cm. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD721", "confidence": 10 }, "VD722": { - "revision": 2, - "explanation": "This is the 13 cm band. The exam range is 2320-2450 MHz, ending at the familiar 2.45 GHz ISM neighbourhood.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "This is the 13 cm band. The exam range is 2320-2450 MHz, ending at the familiar 2.45 GHz ISM neighbourhood. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_amateurfunkbaender.html#VD722", "confidence": 10 }, "VD723": { - "revision": 2, - "explanation": "Class N is the compact starter set: 10 m, 2 m and 70 cm. Memorise the three islands: 28-29.7 MHz, 144-146 MHz and 430-440 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 3, + "explanation": "Class N is the compact starter set: 10 m, 2 m and 70 cm. Memorise the three islands: 28-29.7 MHz, 144-146 MHz and 430-440 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_frequenz.html#VD723", "confidence": 10 }, "VD724": { - "revision": 1, - "explanation": "For class N on 2 m and 70 cm, AFuV Anlage 1 uses an EIRP cap of 10 W rather than a transmitter-output cap.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "For class N on 2 m and 70 cm, AFuV Anlage 1 uses an EIRP cap of 10 W rather than a transmitter-output cap. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_sendeleistung_klasse_n.html#VD724", "confidence": 10 }, "VD725": { - "revision": 1, - "explanation": "EIRP is transmitter power times antenna gain relative to isotropic: $5 W \\cdot 2.5 = 12.5 W$, which exceeds the 10 W class N limit.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "EIRP is transmitter power times antenna gain relative to isotropic: $5 W \\cdot 2.5 = 12.5 W$, which exceeds the 10 W class N limit. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_sendeleistung_klasse_n.html#VD725", "confidence": 10 }, "VD726": { - "revision": 1, - "explanation": "EIRP is transmitter power times antenna gain relative to isotropic: $5 W \\cdot 1.8 = 9 W$, which stays below the 10 W class N limit.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "EIRP is transmitter power times antenna gain relative to isotropic: $5 W \\cdot 1.8 = 9 W$, which stays below the 10 W class N limit. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_sendeleistung_klasse_n.html#VD726", "confidence": 10 }, "VD727": { - "revision": 1, - "explanation": "AFuV Anlage 1 permits class E operation from 1810 to 1850 kHz with a maximum of 100 W PEP.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 permits class E operation from 1810 to 1850 kHz with a maximum of 100 W PEP. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD727", "confidence": 10 }, "VD728": { - "revision": 1, - "explanation": "AFuV Anlage 1 lists 750 W PEP for class A in the 3.5-3.8 MHz band.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 lists 750 W PEP for class A in the 3.5-3.8 MHz band. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD728", "confidence": 10 }, "VD729": { - "revision": 1, - "explanation": "AFuV Anlage 1 gives 3.5-3.8 MHz limits of 750 W PEP for class A and 100 W PEP for class E.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 gives 3.5-3.8 MHz limits of 750 W PEP for class A and 100 W PEP for class E. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD729", "confidence": 10 }, "VD730": { - "revision": 1, - "explanation": "AFuV Anlage 1 limits class A in 10.1-10.15 MHz to 150 W PEP.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 limits class A in 10.1-10.15 MHz to 150 W PEP. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD730", "confidence": 10 }, "VD731": { - "revision": 1, - "explanation": "AFuV Anlage 1 lists 750 W PEP for class A on both 14.000-14.350 MHz and 18.068-18.168 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 lists 750 W PEP for class A on both 14.000-14.350 MHz and 18.068-18.168 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD731", "confidence": 10 }, "VD732": { - "revision": 1, - "explanation": "AFuV Anlage 1 lists 750 W PEP for class A on both 21.000-21.450 MHz and 24.890-24.990 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 lists 750 W PEP for class A on both 21.000-21.450 MHz and 24.890-24.990 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD732", "confidence": 10 }, "VD733": { - "revision": 1, - "explanation": "AFuV Anlage 1 gives 21 MHz and 28 MHz limits of 750 W PEP for class A and 100 W PEP for class E.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 gives 21 MHz and 28 MHz limits of 750 W PEP for class A and 100 W PEP for class E. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD733", "confidence": 10 }, "VD734": { - "revision": 1, - "explanation": "AFuV Anlage 1 gives 144-146 MHz and 430-440 MHz limits of 750 W PEP for class A and 75 W PEP for class E.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 gives 144-146 MHz and 430-440 MHz limits of 750 W PEP for class A and 75 W PEP for class E. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD734", "confidence": 10 }, "VD735": { - "revision": 1, - "explanation": "AFuV Anlage 1 allows class A up to 750 W PEP at 1240-1300 MHz but adds a special 5 W EIRP cap in 1247-1263 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 allows class A up to 750 W PEP at 1240-1300 MHz but adds a special 5 W EIRP cap in 1247-1263 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD735", "confidence": 10 }, "VD736": { - "revision": 1, - "explanation": "For class A between 1300 MHz and 250 GHz, AFuV Anlage 1 lists a maximum transmitter output of 75 W PEP.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "For class A between 1300 MHz and 250 GHz, AFuV Anlage 1 lists a maximum transmitter output of 75 W PEP. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD736", "confidence": 10 }, "VD737": { - "revision": 1, - "explanation": "For class E between 1300 MHz and 250 GHz, AFuV Anlage 1 lists a maximum transmitter output of 5 W PEP.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "For class E between 1300 MHz and 250 GHz, AFuV Anlage 1 lists a maximum transmitter output of 5 W PEP. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_ausgangsleistung.html#VD737", "confidence": 10 }, "VD738": { - "revision": 1, - "explanation": "AFuV Anlage 1 sets the narrow 800 Hz occupied-bandwidth limit for 135.7-137.8 kHz, 472-479 kHz and 10.100-10.150 MHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 sets the narrow 800 Hz occupied-bandwidth limit for 135.7-137.8 kHz, 472-479 kHz and 10.100-10.150 MHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_bandbreite.html#VD738", "confidence": 10 }, "VD739": { - "revision": 1, - "explanation": "AFuV Anlage 1 gives 3.5-3.8 MHz a maximum occupied bandwidth of 2.7 kHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 gives 3.5-3.8 MHz a maximum occupied bandwidth of 2.7 kHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_bandbreite.html#VD739", "confidence": 10 }, "VD740": { - "revision": 1, - "explanation": "AFuV Anlage 1 gives 28.000-29.000 MHz a maximum occupied bandwidth of 7 kHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 gives 28.000-29.000 MHz a maximum occupied bandwidth of 7 kHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_bandbreite.html#VD740", "confidence": 10 }, "VD741": { - "revision": 1, - "explanation": "AFuV Anlage 1 gives 144-146 MHz a maximum occupied bandwidth of 40 kHz.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 gives 144-146 MHz a maximum occupied bandwidth of 40 kHz. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_bandbreite.html#VD741", "confidence": 10 }, "VD742": { - "revision": 1, - "explanation": "AFuV Anlage 1 gives 430-440 MHz a 2 MHz occupied-bandwidth limit, with 7 MHz allowed for AM television transmissions.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 gives 430-440 MHz a 2 MHz occupied-bandwidth limit, with 7 MHz allowed for AM television transmissions. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_bandbreite.html#VD742", "confidence": 10 }, "VD743": { - "revision": 1, - "explanation": "AFuV Anlage 1 caps class N in the 10 m band at 10 W ERP.", - "source": "https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html", + "revision": 2, + "explanation": "AFuV Anlage 1 caps class N in the 10 m band at 10 W ERP. Hilfsmittel: the frequency-allocation table in the official exam aids (Hilfsmittel) lists these band limits and usage parameters directly, so in the exam this is a table lookup rather than a memory item.", + "source": "https://50ohm.de/NEA_sendeleistung_klasse_n.html#VD743", "confidence": 10 }, "VE101": { - "revision": 1, + "revision": 2, "explanation": "The TKG is a general telecommunications law; amateur radio has its own law, but frequency-use and enforcement rules from the TKG can still apply.", - "source": "https://www.gesetze-im-internet.de/tkg_2021/BJNR185810021.html", + "source": "https://50ohm.de/NEA_gesetze_vorschriften.html#VE101", "confidence": 9 }, "VE102": { - "revision": 1, - "explanation": "TKG §91 states the general rule that every frequency use needs a prior frequency assignment unless the law provides otherwise.", - "source": "https://www.gesetze-im-internet.de/tkg_2021/BJNR185810021.html", + "revision": 3, + "explanation": "The principle is that every frequency use needs a prior frequency assignment — either an individual assignment or a general assignment (as amateur radio has); without one, transmitting is not allowed.", + "source": "https://50ohm.de/NEA_frequenzzuteilung.html#VE102", "confidence": 10 }, "VE103": { - "revision": 1, + "revision": 2, "explanation": "Using frequencies without the required frequency assignment is a TKG administrative offence.", - "source": "https://www.gesetze-im-internet.de/tkg_2021/BJNR185810021.html", + "source": "https://50ohm.de/NEA_verstoesse_und_folgen.html#VE103", "confidence": 10 }, "VE201": { - "revision": 1, - "explanation": "Unauthorised listening to the non-publicly spoken word is a criminal offence under StGB §201, independent of holding an amateur licence.", - "source": "https://www.gesetze-im-internet.de/stgb/__201.html", + "revision": 3, + "explanation": "Listening to the non-publicly spoken word is a criminal offence in its own right; holding an amateur licence gives no exception, so an amateur station may never be used for it.", + "source": "https://50ohm.de/NEA_fernmeldegeheimnis_abhoerverbot.html#VE201", "confidence": 10 }, "VE202": { - "revision": 1, + "revision": 2, "explanation": "TDDDG protects communications not intended for the recipient; receiving, using or passing on such messages violates that confidentiality duty.", - "source": "https://www.gesetze-im-internet.de/ttdsg/__5.html", + "source": "https://50ohm.de/NEA_fernmeldegeheimnis_abhoerverbot.html#VE202", "confidence": 10 }, "VE203": { - "revision": 1, + "revision": 2, "explanation": "TDDDG §5 bars disclosing both the content and the fact of receiving non-public/non-general messages, except where emergency and disaster rules justify it.", - "source": "https://www.gesetze-im-internet.de/ttdsg/__5.html", + "source": "https://50ohm.de/NEA_fernmeldegeheimnis_abhoerverbot.html#VE203", "confidence": 10 }, "VE204": { - "revision": 1, + "revision": 2, "explanation": "TDDDG prohibits disguised transmitting devices suited to unnoticed eavesdropping on non-public speech, including possession and manufacture.", - "source": "https://www.gesetze-im-internet.de/ttdsg/__5.html", + "source": "https://50ohm.de/NEA_fernmeldegeheimnis_abhoerverbot.html#VE204", "confidence": 10 }, "VE301": { - "revision": 1, + "revision": 2, "explanation": "Before escalating an EMC dispute, reducing power is a practical interim measure that may remove the interference and preserve neighbourly peace.", - "source": "https://www.gesetze-im-internet.de/emvg_2016/BJNR287910016.html", + "source": "https://50ohm.de/NEA_stoerungen_vermeiden.html#VE301", "confidence": 8 }, "VE302": { - "revision": 1, + "revision": 2, "explanation": "If local remedies fail, BNetzA is the competent authority to investigate radio-interference causes.", - "source": "https://www.gesetze-im-internet.de/emvg_2016/BJNR287910016.html", + "source": "https://50ohm.de/NEA_stoerungen_vermeiden.html#VE302", "confidence": 9 }, "VE303": { - "revision": 1, + "revision": 2, "explanation": "When both installations are compliant but incompatibility remains, EMVG gives BNetzA authority to arrange remedial measures with the parties.", - "source": "https://www.gesetze-im-internet.de/emvg_2016/BJNR287910016.html", + "source": "https://50ohm.de/NEA_stoerungen_vermeiden.html#VE303", "confidence": 9 }, "VE304": { - "revision": 1, + "revision": 2, "explanation": "EMVG lets BNetzA arrange remedial measures in cooperation with affected parties when compliant equipment still causes a local EMC problem.", - "source": "https://www.gesetze-im-internet.de/emvg_2016/BJNR287910016.html", + "source": "https://50ohm.de/NEA_stoerungen_vermeiden.html#VE304", "confidence": 9 }, "VE305": { - "revision": 1, + "revision": 2, "explanation": "If the amateur field strength at the affected receiver is below the relevant immunity reference level, the amateur station is not the non-compliant part and may continue operation.", - "source": "https://www.gesetze-im-internet.de/emvg_2016/BJNR287910016.html", + "source": "https://50ohm.de/NEA_stoerungen_vermeiden.html#VE305", "confidence": 8 }, "VE306": { - "revision": 1, + "revision": 2, "explanation": "If the field strength at the cable system stays below the recommended immunity level, the amateur transmission is within the assumed compatibility boundary.", - "source": "https://www.gesetze-im-internet.de/emvg_2016/BJNR287910016.html", + "source": "https://50ohm.de/NEA_stoerungen_vermeiden.html#VE306", "confidence": 8 }, "VE307": { - "revision": 2, + "revision": 3, "explanation": "Interference on every band usually points to a nearby broadband noise source, not propagation or one amateur band. The practical first step is to isolate local household electronics and power supplies before escalating.", - "source": "https://www.gesetze-im-internet.de/emvg_2016/BJNR287910016.html", + "source": "https://50ohm.de/NEA_empfangsstoerungen.html#VE307", "confidence": 8 }, "VE308": { - "revision": 1, + "revision": 2, "explanation": "A receiver has no general right to be free of all interference; compliant devices under EMVG or FuAG may still produce disturbance the amateur must tolerate.", - "source": "https://www.gesetze-im-internet.de/emvg_2016/BJNR287910016.html", + "source": "https://50ohm.de/NEA_empfangsstoerungen.html#VE308", "confidence": 9 }, "VE309": { - "revision": 1, + "revision": 2, "explanation": "A time/type log and suspected source give BNetzA evidence for pattern matching and field investigation of recurring interference.", - "source": "https://www.gesetze-im-internet.de/emvg_2016/BJNR287910016.html", + "source": "https://50ohm.de/NEA_empfangsstoerungen.html#VE309", "confidence": 8 }, "VE401": { - "revision": 1, + "revision": 2, "explanation": "The FuAG implements the market rules for radio equipment, including making radio equipment available, free movement and putting it into service.", - "source": "https://www.gesetze-im-internet.de/fuag/FuAG.pdf", + "source": "https://50ohm.de/NEA_recht_zum_selbstbau.html#VE401", "confidence": 10 }, "VE402": { - "revision": 1, + "revision": 2, "explanation": "Radio equipment made available on the market, including amateur equipment sold commercially, falls under the FuAG.", - "source": "https://www.gesetze-im-internet.de/fuag/FuAG.pdf", + "source": "https://50ohm.de/NEA_recht_zum_selbstbau.html#VE402", "confidence": 10 }, "VE403": { - "revision": 1, + "revision": 2, "explanation": "Serially manufactured amateur radio equipment is market equipment, so it must meet FuAG essential requirements and carry CE marking.", - "source": "https://www.gesetze-im-internet.de/fuag/FuAG.pdf", + "source": "https://50ohm.de/NEA_recht_zum_selbstbau.html#VE403", "confidence": 10 }, "VE404": { - "revision": 1, + "revision": 2, "explanation": "Commercial receivers capable of receiving amateur frequencies are market radio equipment, so FuAG requirements apply.", - "source": "https://www.gesetze-im-internet.de/fuag/FuAG.pdf", + "source": "https://50ohm.de/NEA_recht_zum_selbstbau.html#VE404", "confidence": 10 }, "VE405": { - "revision": 1, + "revision": 2, "explanation": "FuAG excludes amateur radio equipment assembled by radio amateurs for experimental and scientific purposes, so those home-built stations do not need FuAG conformity proof.", - "source": "https://www.gesetze-im-internet.de/fuag/FuAG.pdf", + "source": "https://50ohm.de/NEA_recht_zum_selbstbau.html#VE405", "confidence": 10 }, "VE501": { - "revision": 2, + "revision": 3, "explanation": "EMVU is not about whether your radio works; it is about electromagnetic fields in the environment. In exam terms, read it as person/environment protection from RF exposure.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_personenschutzabstand.html#VE501", "confidence": 9 }, "VE502": { - "revision": 1, + "revision": 2, "explanation": "The fixed amateur-station operator is responsible for demonstrating and maintaining electromagnetic environmental compatibility at the site.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_personenschutzabstand.html#VE502", "confidence": 10 }, "VE503": { - "revision": 1, + "revision": 2, "explanation": "The BEMFV is the regulation that sets the proof procedure for limiting electromagnetic fields from fixed amateur stations.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_personenschutzabstand.html#VE503", "confidence": 10 }, "VE504": { - "revision": 2, + "revision": 3, "explanation": "The BEMFV procedure is a self-responsibility model: calculate or measure the safety distance, document it, and declare that people are protected. It is not just paperwork; it defines your safe operating envelope.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_personenschutzabstand.html#VE504", "confidence": 10 }, "VE505": { - "revision": 1, + "revision": 2, "explanation": "Person-protection field limits come from the 26th BImSchV and are applied through the BEMFV proof procedure.", - "source": "https://www.gesetze-im-internet.de/bimschv_26/BJNR196600996.html", + "source": "https://50ohm.de/NEA_personenschutzabstand.html#VE505", "confidence": 10 }, "VE506": { - "revision": 1, + "revision": 2, "explanation": "For fixed amateur stations at 10 W EIRP or more, BEMFV requires the safety distance to be determined by calculation or measurement and documented.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE506", "confidence": 10 }, "VE507": { - "revision": 2, + "revision": 3, "explanation": "The trigger number is 10 W EIRP for fixed amateur stations. Memorise it as: fixed station plus 10 W EIRP or more means EMVU documentation.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE507", "confidence": 10 }, "VE508": { - "revision": 1, + "revision": 2, "explanation": "Every operator of a fixed amateur station at or above 10 W EIRP must use the BEMFV notification procedure.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE508", "confidence": 10 }, "VE509": { - "revision": 1, + "revision": 2, "explanation": "The BEMFV notification must be submitted to the responsible BNetzA field office before starting operation.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE509", "confidence": 10 }, "VE510": { - "revision": 2, + "revision": 3, "explanation": "The notification only covers the station as described. If antennas, power, location or other relevant facts change so the old assumptions no longer fit, redo the procedure.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE510", "confidence": 10 }, "VE511": { - "revision": 2, + "revision": 3, "explanation": "The notification is your binding statement to BNetzA: I checked the RF exposure limits and my fixed station stays within them. The responsibility remains with the operator.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_personenschutzabstand.html#VE511", "confidence": 10 }, "VE512": { - "revision": 1, + "revision": 2, "explanation": "BEMFV requires a clear drawing of the site-related safety distance and the area controlled by the operator with the notification.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE512", "confidence": 10 }, "VE513": { - "revision": 1, + "revision": 2, "explanation": "From commissioning onward, the operator must keep the supporting compliance documentation ready for BNetzA, including antenna data and site drawings as needed.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE513", "confidence": 10 }, "VE514": { - "revision": 1, + "revision": 2, "explanation": "After notification, the operator must keep the documentation current and re-notify after material changes that invalidate the original assumptions.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE514", "confidence": 10 }, "VE515": { - "revision": 2, + "revision": 3, "explanation": "BNetzA accepts several proof methods for amateur stations, including WattWächter, simplified assessment, measurements, and near- or far-field calculations.", - "source": "https://www.dsc.bund.de/SharedDocs/Downloads/DE/Sachgebiete/Telekommunikation/Verbraucher/ElektromagnetischeFelder/Anzeige_Afu/anleitung_anzeige20160616.pdf?__blob=publicationFile&v=1", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE515", "confidence": 8 }, "VE516": { - "revision": 1, + "revision": 2, "explanation": "The safety distance must cover all emissions the operator intends to make simultaneously, because simultaneous fields add at the exposure location.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE516", "confidence": 10 }, "VE517": { - "revision": 1, + "revision": 2, "explanation": "Overlapping safety distances require joint assessment when the antennas can transmit at the same time, because exposure is combined.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_anzeige_ortsfester_amateurfunkanlagen.html#VE517", "confidence": 10 }, "VE518": { - "revision": 1, + "revision": 2, "explanation": "If other certificate-requiring fixed radio systems are already at the site and total site EIRP reaches 10 W, BEMFV requires a site certificate.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_standortbescheinigung.html#VE518", "confidence": 10 }, "VE519": { - "revision": 1, + "revision": 2, "explanation": "For a fixed amateur station, BEMFV requires a site certificate only when the intended site already has fixed radio systems subject to the site-certificate procedure.", - "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "source": "https://50ohm.de/NEA_standortbescheinigung.html#VE519", "confidence": 10 }, "VE601": { - "revision": 2, + "revision": 3, "explanation": "Home-built does not mean safety rules disappear. The regulation expects generally recognised engineering practice, so VDE rules are the benchmark for safe construction and installation.", - "source": "VDE 0855-300 and DIN EN 62305/VDE 0185-305", + "source": "https://50ohm.de/NEA_gefahren.html#VE601", "confidence": 8 }, "VE602": { - "revision": 2, + "revision": 3, "explanation": "Outdoor antenna structures are building works, so the applicable construction law is the law of the German federal state where they are erected.", - "source": "https://50ohm.de/N_antennen_baurecht_haftung.html", + "source": "https://50ohm.de/NEA_antennen_baurecht_haftung.html#VE602", "confidence": 8 }, "VE603": { - "revision": 2, + "revision": 3, "explanation": "Lightning protection is about using recognised technical rules, not improvising. For antenna installations, the exam points you to the VDE standards as that recognised rule set.", - "source": "VDE 0855-300 and DIN EN 62305/VDE 0185-305", + "source": "https://50ohm.de/NEA_n_blitzschutz.html#VE603", "confidence": 8 }, "VE604": { - "revision": 2, + "revision": 3, "explanation": "Split the safety topics: VDE 0855-300 is the amateur-station earthing/equipotential-bonding rule; VDE 0185-305 is the lightning-protection series when the building has lightning protection.", - "source": "VDE 0855-300 and DIN EN 62305/VDE 0185-305", + "source": "https://50ohm.de/NEA_blitzschutz.html#VE604", "confidence": 8 }, "VE701": { - "revision": 2, + "revision": 3, "explanation": "The annual contribution is not a usage fee per QSO; it funds frequency protection and EMC work. Once you hold the amateur authorisation/call sign, you are part of that cost-recovery system.", - "source": "Frequenzschutzbeitragsverordnung (FSBeitrV)", + "source": "https://50ohm.de/NEA_gebuehren_beitraege.html#VE701", "confidence": 8 }, "VE702": { - "revision": 2, + "revision": 3, "explanation": "The trigger is having the admission, not how often you transmit. Memorise: licence held equals annual contribution owed, even for little or no activity.", - "source": "Frequenzschutzbeitragsverordnung (FSBeitrV)", + "source": "https://50ohm.de/NEA_gebuehren_beitraege.html#VE702", "confidence": 8 }, "VE703": { - "revision": 2, + "revision": 3, "explanation": "Fees are for individual administrative acts, such as issuing the admission and assigning the person-bound call sign. Think one-time authority action, not the annual contribution.", - "source": "Besondere Gebührenverordnung BNetzA (BNetzABGebV)", + "source": "https://50ohm.de/NEA_gebuehren_beitraege.html#VE703", "confidence": 8 }, "VE704": { - "revision": 2, + "revision": 3, "explanation": "BNetzA fees and contributions are public-law debts. If they are not paid, the state does not need an ordinary private lawsuit first; administrative enforcement can follow.", - "source": "Verwaltungs-Vollstreckungsgesetz (VwVG)", + "source": "https://50ohm.de/NEA_gebuehren_beitraege.html#VE704", "confidence": 8 }, "VE705": { - "revision": 2, + "revision": 3, "explanation": "Aircraft operation requires the consent of the pilot in command because that person is responsible for the aircraft and onboard radio use.", - "source": "https://50ohm.de/NE_rufzeichenzusaetze.html", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#VE705", "confidence": 8 }, "VE706": { - "revision": 2, + "revision": 3, "explanation": "On a ship in international waters, amateur operation is possible only with the master's consent because the master controls shipboard operations.", - "source": "https://50ohm.de/NE_rufzeichenzusaetze.html", + "source": "https://50ohm.de/NEA_rufzeichenzusaetze.html#VE706", "confidence": 8 }, "VE707": { - "revision": 3, + "revision": 4, "explanation": "For antenna damage, responsibility follows control of the installation. The owner or operator is the person expected to build, maintain and secure it, so they bear liability toward third parties.", - "source": "https://50ohm.de/N_antennen_baurecht_haftung.html", + "source": "https://50ohm.de/NEA_antennen_baurecht_haftung.html#VE707", "confidence": 8 } }