From a47795b08120efc0cd22856b5494b0f43a88c79a Mon Sep 17 00:00:00 2001 From: Renat Nurgaliyev Date: Sat, 23 May 2026 00:07:59 +0200 Subject: [PATCH] Add explanations for E* questions Automatically generated using Codex and GPT 5.5 in high reasoning mode and Claude Code with Opus 4.7 in high reasoning mode, models cross checking each other --- explanations.json | 2778 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 2778 insertions(+) diff --git a/explanations.json b/explanations.json index fdde375..e87776f 100644 --- a/explanations.json +++ b/explanations.json @@ -1031,6 +1031,2784 @@ "source": "https://www.bundesnetzagentur.de/SharedDocs/Downloads/DE/Sachgebiete/Telekommunikation/Unternehmen_Institutionen/Frequenzen/Amateurfunk/Fragenkatalog/BetriebVorschriftFragKlAuEId7830pdf.pdf?__blob=publicationFile", "confidence": 8 }, + "EA101": { + "revision": 1, + "explanation": "Capacitance is charge stored per voltage, $C = Q/U$, and its named SI-derived unit is the farad.", + "source": "https://50ohm.de/EA_kondensator_1.html", + "confidence": 8 + }, + "EA102": { + "revision": 1, + "explanation": "Inductance describes magnetic flux linkage per current; the named SI-derived unit for it is the henry.", + "source": "https://50ohm.de/EA_spule_1.html", + "confidence": 8 + }, + "EA103": { + "revision": 1, + "explanation": "For a plate field, $E = U/d$, so the unit is volts divided by metres: V/m.", + "source": "https://50ohm.de/EA_e_feld.html", + "confidence": 8 + }, + "EA104": { + "revision": 1, + "explanation": "For a long straight conductor, $H = I/(2\\pi r)$, so magnetic field strength has amperes divided by metres: A/m.", + "source": "https://50ohm.de/EA_h_feld.html", + "confidence": 8 + }, + "EA105": { + "revision": 2, + "explanation": "Bandwidth is a frequency interval, so it is measured in hertz just like frequency.", + "source": "https://50ohm.de/E_slide_e_modulation.html", + "confidence": 7 + }, + "EA106": { + "revision": 1, + "explanation": "A data rate counts transferred bits per unit time, so the usual unit is bit/s rather than baud or hertz.", + "source": "https://50ohm.de/NEA_datenuebertragungsdrate.html", + "confidence": 8 + }, + "EA107": { + "revision": 1, + "explanation": "Power ratios in dB use $10\\log_{10}(P_2/P_1)$; doubling power gives $10\\log_{10}(2) \\approx 3$ dB.", + "source": "https://50ohm.de/E_dezibel_1.html", + "confidence": 8 + }, + "EA108": { + "revision": 1, + "explanation": "$0.00042$ A equals $420 \\cdot 10^{-6}$ A because moving the decimal six places expresses the value in micro-units.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "confidence": 8 + }, + "EA109": { + "revision": 1, + "explanation": "$0.042$ A equals $42 \\cdot 10^{-3}$ A because milli means $10^{-3}$.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "confidence": 8 + }, + "EA110": { + "revision": 1, + "explanation": "$4,200,000$ Hz is $4.2 \\cdot 10^6$ Hz in scientific notation.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "confidence": 8 + }, + "EA111": { + "revision": 1, + "explanation": "$0.01$ mV is $0.01 \\cdot 10^{-3}$ V, which is $10 \\cdot 10^{-6}$ V.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "confidence": 8 + }, + "EA112": { + "revision": 1, + "explanation": "$0.002$ MOhm is $0.002 \\cdot 10^6$ ohm, which is $2 \\cdot 10^3$ ohm.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "confidence": 8 + }, + "EA113": { + "revision": 1, + "explanation": "$2 \\cdot 10^{-7}$ W divided by $10^{-6}$ W/µW gives $0.2$ µW.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "confidence": 8 + }, + "EA114": { + "revision": 1, + "explanation": "$5 \\cdot 10^{-1}$ W is $0.5$ W; multiplying by 1000 converts that to 500 mW.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "confidence": 8 + }, + "EA115": { + "revision": 1, + "explanation": "Micro is $10^{-6}$ and nano is $10^{-9}$, so $0.22$ µF is $0.22 \\cdot 1000 = 220$ nF.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "confidence": 8 + }, + "EA116": { + "revision": 1, + "explanation": "Kilo to mega divides by 1000, so 3750 kHz is 3.750 MHz.", + "source": "https://50ohm.de/NEA_zehnerpotenzen.html", + "confidence": 8 + }, + "EA201": { + "revision": 1, + "explanation": "Digital circuits can represent two robust electrical states as 0 and 1, so binary maps naturally to switching devices such as transistors.", + "source": "https://50ohm.de/EA_binaer.html", + "confidence": 8 + }, + "EA202": { + "revision": 1, + "explanation": "Each bit doubles the number of possible states; with 3 bits there are $2^3 = 8$ states.", + "source": "https://50ohm.de/EA_binaer.html", + "confidence": 8 + }, + "EA203": { + "revision": 1, + "explanation": "Each bit doubles the number of possible states; with 4 bits there are $2^4 = 16$ states.", + "source": "https://50ohm.de/EA_binaer.html", + "confidence": 8 + }, + "EA204": { + "revision": 1, + "explanation": "A five-bit binary number has $2^5$ possible combinations, so it can represent 32 values.", + "source": "https://50ohm.de/EA_binaer.html", + "confidence": 8 + }, + "EA205": { + "revision": 1, + "explanation": "$01001110_2 = 64 + 8 + 4 + 2 = 78$; the leading zero only pads the width.", + "source": "https://50ohm.de/EA_binaer.html", + "confidence": 8 + }, + "EA206": { + "revision": 1, + "explanation": "$10001110_2 = 128 + 8 + 4 + 2 = 142$.", + "source": "https://50ohm.de/EA_binaer.html", + "confidence": 8 + }, + "EA207": { + "revision": 1, + "explanation": "$10011100_2 = 128 + 16 + 8 + 4 = 156$.", + "source": "https://50ohm.de/EA_binaer.html", + "confidence": 8 + }, + "EA208": { + "revision": 1, + "explanation": "$11111000_2 = 128 + 64 + 32 + 16 + 8 = 248$.", + "source": "https://50ohm.de/EA_binaer.html", + "confidence": 8 + }, + "EB101": { + "revision": 2, + "explanation": "Between large parallel plates the field lines are almost straight, parallel, and evenly spaced, so the approximation is a homogeneous electric field.", + "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "confidence": 8 + }, + "EB102": { + "revision": 2, + "explanation": "For a plate capacitor, $E = U/d$. With $d = 0.6$ cm $= 0.006$ m, $E = 9/0.006 = 1500$ V/m.", + "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "confidence": 8 + }, + "EB103": { + "revision": 2, + "explanation": "Use $E = U/d$ and convert $0.15$ mm to $1.5 \\cdot 10^{-4}$ m. Thus $300/(1.5 \\cdot 10^{-4}) = 2.0 \\cdot 10^6$ V/m = 2000 kV/m.", + "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "confidence": 8 + }, + "EB104": { + "revision": 2, + "explanation": "Breakdown strength is an electric field strength, so $U = E \\cdot d$. $400$ kV/cm across $0.15$ mm gives $400 \\cdot 0.015 = 6$ kV.", + "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "confidence": 8 + }, + "EB105": { + "revision": 2, + "explanation": "At a vertical antenna the electric field lines run between the conductor and the surrounding reference/ground; the concentric loops around the conductor are the magnetic field, not the marked vertical electric lines.", + "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "confidence": 7 + }, + "EB201": { + "revision": 1, + "explanation": "A current through a straight conductor creates magnetic field lines that close around the conductor; in the simple straight-wire case they are concentric circles.", + "source": "https://50ohm.de/EA_h_feld.html", + "confidence": 8 + }, + "EB202": { + "revision": 2, + "explanation": "A long current-carrying solenoid concentrates nearly parallel magnetic field lines inside the winding, so its interior field is approximately homogeneous and magnetic.", + "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "confidence": 8 + }, + "EB203": { + "revision": 1, + "explanation": "For a toroidal core, $H = NI/l_m$ with $l_m = \\pi d$. Here $H = 6 \\cdot 2.5/(\\pi \\cdot 0.026) \\approx 183.6$ A/m.", + "source": "https://50ohm.de/NEA_slide_nea_em_feld.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EB204": { + "revision": 1, + "explanation": "Iron is ferromagnetic at room temperature; copper and aluminium are not ferromagnetic, and chromium is not the standard room-temperature ferromagnet used here.", + "source": "https://50ohm.de/E_spule_1.html", + "confidence": 8 + }, + "EB205": { + "revision": 1, + "explanation": "A conductive copper or aluminium core supports induced RF currents that oppose field penetration, so the effective magnetic-field cross-section of the coil is reduced. The 50ohm page notes that the catalog wording is simplified, so this is partly a memorize-the-official-answer item.", + "source": "https://50ohm.de/NEA_spule_1.html", + "confidence": 7 + }, + "EB206": { + "revision": 2, + "explanation": "Around a vertical current-carrying antenna conductor, the closed concentric loops are magnetic field lines. The electric field lines are the open/vertical ones tied to the conductor and ground reference.", + "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "confidence": 7 + }, + "EB301": { + "revision": 2, + "explanation": "Radio radiation needs time-varying fields. A time-varying current in a conductor, such as an antenna, produces coupled electric and magnetic field components.", + "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "confidence": 8 + }, + "EB302": { + "revision": 2, + "explanation": "An electromagnetic wave propagates because changing electric and magnetic fields continually sustain each other; neither field travels independently in the far-field wave model.", + "source": "https://50ohm.de/NEA_slide_nea_em_feld.html", + "confidence": 8 + }, + "EB303": { + "revision": 1, + "explanation": "In free-space far-field propagation the electric and magnetic field vectors are transverse to each other, so their angle is $90^\\circ$.", + "source": "https://50ohm.de/NEA_fernfeld.html", + "confidence": 8 + }, + "EB304": { + "revision": 1, + "explanation": "In an undisturbed far field, the $E$ field, $H$ field, and propagation direction form a mutually perpendicular triad.", + "source": "https://50ohm.de/NEA_fernfeld.html", + "confidence": 8 + }, + "EB305": { + "revision": 2, + "explanation": "Electromagnetic-wave polarization is defined by the orientation or motion of the electric-field vector, not by the magnetic field or travel direction.", + "source": "https://50ohm.de/NEA_polarisation_2.html", + "confidence": 8 + }, + "EB306": { + "revision": 2, + "explanation": "Polarization follows the electric-field vector in the drawing. Here that vector lies horizontally, so the wave is horizontally polarized.", + "source": "https://50ohm.de/NEA_polarisation_2.html", + "confidence": 7 + }, + "EB307": { + "revision": 2, + "explanation": "Polarization is read from the electric-field vector. In this figure the electric field is vertical, so the wave is vertically polarized.", + "source": "https://50ohm.de/NEA_polarisation_2.html", + "confidence": 7 + }, + "EB308": { + "revision": 2, + "explanation": "When the electric-field direction rotates during propagation rather than staying along one fixed line, the wave is circularly polarized.", + "source": "https://50ohm.de/NEA_polarisation_2.html", + "confidence": 7 + }, + "EB309": { + "revision": 2, + "explanation": "For a linear antenna, the transmitted wave's polarization follows the orientation of the radiating element in the main direction. The shown elements are horizontal, so the signal is horizontally polarized.", + "source": "https://50ohm.de/NEA_polarisation_2.html", + "confidence": 7 + }, + "EB310": { + "revision": 2, + "explanation": "A linearly radiating element gives polarization in the same orientation as the electric field it launches. The shown main-direction field is vertical, so the signal is vertically polarized.", + "source": "https://50ohm.de/NEA_polarisation_2.html", + "confidence": 7 + }, + "EB311": { + "revision": 1, + "explanation": "Use $\\lambda = c/f$ with $c \\approx 300$ Mm/s. $300/1.84 \\approx 163$, so 1.84 MHz corresponds to about 163 m.", + "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "confidence": 8 + }, + "EB312": { + "revision": 1, + "explanation": "Using $\\lambda \\approx 300/f_{MHz}$, $300/21 \\approx 14.29$ m.", + "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "confidence": 8 + }, + "EB313": { + "revision": 1, + "explanation": "Using $\\lambda \\approx 300/f_{MHz}$, $300/28.5 \\approx 10.5$ m.", + "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "confidence": 8 + }, + "EB314": { + "revision": 1, + "explanation": "Rearrange $\\lambda = c/f$ to $f \\approx 300/\\lambda$ in MHz for metres. $300/80.0 = 3.75$ MHz.", + "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "confidence": 8 + }, + "EB315": { + "revision": 1, + "explanation": "A wavelength of 30 mm is 0.03 m. $f = c/\\lambda \\approx 3 \\cdot 10^8 / 0.03 = 1 \\cdot 10^{10}$ Hz = 10 GHz.", + "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "confidence": 8 + }, + "EB316": { + "revision": 1, + "explanation": "A wavelength of 10 cm is 0.1 m. $f = c/\\lambda \\approx 3 \\cdot 10^8 / 0.1 = 3 \\cdot 10^9$ Hz = 3 GHz.", + "source": "https://50ohm.de/NE_wellenlaenge_2.html", + "confidence": 8 + }, + "EB401": { + "revision": 2, + "explanation": "For a sine wave, the peak value is RMS times sqrt(2). Mains 230 V is an RMS value, so 230 * 1.414 is about 325 V.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 8 + }, + "EB402": { + "revision": 2, + "explanation": "Peak-to-peak voltage is twice the peak value. From 230 V RMS, the peak is about 325 V, so peak-to-peak is about 650 V, rounded here to 651 V.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 8 + }, + "EB403": { + "revision": 2, + "explanation": "For a sine wave, peak voltage is RMS times sqrt(2): 12 V * 1.414 is about 17 V. Peak-to-peak is twice that, about 34 V.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 8 + }, + "EB404": { + "revision": 2, + "explanation": "For a sine wave, RMS is peak divided by sqrt(2). 12 V / 1.414 is about 8.5 V.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 8 + }, + "EB405": { + "revision": 2, + "explanation": "A DC voltage that gives the same heating power as a sine wave is the RMS value. For a 1 V sine peak, RMS is 1/sqrt(2), about 0.7 V in either polarity.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 8 + }, + "EB406": { + "revision": 2, + "explanation": "Peak-to-peak voltage is the vertical distance from the lowest trough to the highest crest on the screen. Reading the divisions in the shown trace gives 12 V.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 7 + }, + "EB407": { + "revision": 2, + "explanation": "The peak-to-peak value is twice the peak value shown in the diagram. A 20 V peak therefore gives 40 V peak-to-peak.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 7 + }, + "EB408": { + "revision": 2, + "explanation": "Frequency is the reciprocal of period: f = 1/T. With T = 50 microseconds, f = 1/(50e-6 s) = 20000 Hz = 20 kHz.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 8 + }, + "EB409": { + "revision": 2, + "explanation": "Read one period from the oscilloscope grid, then use f = 1/T. The trace period is about 12 microseconds, so f is about 83.3 kHz.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 7 + }, + "EB410": { + "revision": 2, + "explanation": "The oscilloscope trace spans 4 divisions at 5 ms/div, so T = 20 ms. f = 1/0.020 s = 50 Hz.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 7 + }, + "EB411": { + "revision": 2, + "explanation": "The trace period is 4 divisions at 0.03 microseconds/div, so T = 0.12 microseconds. f = 1/T is about 8.33 MHz.", + "source": "https://50ohm.de/NE_oszilloskop_1.html", + "confidence": 7 + }, + "EB501": { + "revision": 1, + "explanation": "PEP is defined at the crest of the modulation envelope: it is the average power over one RF cycle at that highest envelope point under normal operating conditions.", + "source": "https://life.itu.int/radioclub/rr/art1.pdf", + "confidence": 9 + }, + "EB502": { + "revision": 1, + "explanation": "Mean transmitter power is averaged over a time interval long enough compared with the lowest modulation frequency period, so it describes the longer-term power delivered to the antenna feed line.", + "source": "https://life.itu.int/radioclub/rr/art1.pdf", + "confidence": 9 + }, + "EB503": { + "revision": 1, + "explanation": "For a purely ohmic load, AC power formulas keep the same form when voltage and current are RMS values. Peak values would overstate the heating power.", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB504": { + "revision": 1, + "explanation": "Combine P = U * I with Ohm's law I = U/R to get P = U^2/R. Solving for voltage gives U = sqrt(P * R).", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB505": { + "revision": 1, + "explanation": "From P = I^2 * R, current is I = sqrt(P/R). From P = U^2/R, voltage is U = sqrt(P * R).", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB506": { + "revision": 1, + "explanation": "Rearrange P = U^2/R to get R = U^2/P, and rearrange P = I^2 * R to get R = P/I^2.", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB507": { + "revision": 1, + "explanation": "Use RMS voltage in P = U^2/R for the 50 Ohm load. 100^2/50 = 10000/50 = 200 W.", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB508": { + "revision": 1, + "explanation": "Use P = I^2 * R with RMS current. 2^2 * 50 = 4 * 50 = 200 W.", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB509": { + "revision": 1, + "explanation": "The resistor power is P = U^2/R. With 10 V across 100 Ohm, P = 100/100 = 1.00 W, so the rating must be at least that.", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB510": { + "revision": 1, + "explanation": "Check both limits. The power limit gives U = sqrt(P * R) = sqrt(1 W * 10000 Ohm) = 100 V, which is below the 700 V voltage limit.", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB511": { + "revision": 1, + "explanation": "The power limit gives U = sqrt(P * R) = sqrt(6 W * 100000 Ohm) about 775 V. That is below the 1000 V voltage rating, so power is the limiting factor.", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB512": { + "revision": 1, + "explanation": "From P = I^2 * R, I = sqrt(P/R). sqrt(23.0/120) is about 0.438 A, or 438 mA.", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB513": { + "revision": 1, + "explanation": "A 25 V peak-to-peak sine has a 12.5 V peak, so RMS voltage is 12.5/sqrt(2) about 8.84 V. Through 1000 Ohm, that is about 8.8 mA RMS.", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EB514": { + "revision": 1, + "explanation": "With 11 equal resistors in parallel, each resistor can still dissipate 5 W. The total rating is 11 * 5 W = 55 W.", + "source": "https://50ohm.de/EA_leistung_2.html", + "confidence": 8 + }, + "EC101": { + "revision": 1, + "explanation": "Wirewound resistors can dissipate high power, but the winding adds inductance, so they are best suited to DC and low-frequency high-load use.", + "source": "https://50ohm.de/E_widerstand_materialien.html", + "confidence": 8 + }, + "EC102": { + "revision": 1, + "explanation": "Metal-film resistors are made for tight value tolerance and low temperature dependence, which is why they are used as precision resistors.", + "source": "https://50ohm.de/E_widerstand_materialien.html", + "confidence": 8 + }, + "EC103": { + "revision": 1, + "explanation": "Metal-oxide film resistors are relatively low-inductance and stable at higher frequencies, unlike wirewound parts whose winding behaves like an inductor.", + "source": "https://50ohm.de/E_widerstand_materialien.html", + "confidence": 8 + }, + "EC104": { + "revision": 1, + "explanation": "A VHF/UHF dummy load should behave like a pure resistance. Low stray inductance and capacitance keep the impedance near 50 Ohm as frequency rises.", + "source": "https://50ohm.de/E_widerstand_materialien.html", + "confidence": 8 + }, + "EC105": { + "revision": 1, + "explanation": "Ten 500 Ohm resistors in parallel give 500/10 = 50 Ohm. Carbon-film parts avoid the wirewound inductance that would spoil a dummy load at RF.", + "source": "https://50ohm.de/E_widerstand_materialien.html", + "confidence": 8 + }, + "EC106": { + "revision": 1, + "explanation": "Ten equal 500 Ohm resistors in parallel give 50 Ohm, and unwound carbon-film parts keep parasitic inductance low enough for this RF dummy-load use.", + "source": "https://50ohm.de/E_widerstand_materialien.html", + "confidence": 8 + }, + "EC107": { + "revision": 1, + "explanation": "For VHF dummy loads, unwound metal-oxide resistors are preferred because they can be made low-inductance and thermally robust.", + "source": "https://50ohm.de/E_widerstand_materialien.html", + "confidence": 8 + }, + "EC108": { + "revision": 1, + "explanation": "NTC thermistors have a deliberately temperature-dependent resistance, making them useful as temperature sensors.", + "source": "https://50ohm.de/E_widerstand_ntc_ptc.html", + "confidence": 8 + }, + "EC109": { + "revision": 1, + "explanation": "The symbol shows a temperature-dependent resistor whose resistance falls as temperature rises; that negative temperature coefficient is an NTC thermistor.", + "source": "https://50ohm.de/E_widerstand_ntc_ptc.html", + "confidence": 7 + }, + "EC110": { + "revision": 1, + "explanation": "An NTC symbol indicates temperature dependence with resistance decreasing as temperature increases. In the shown choices, that is the symbol with the temperature arrow up and resistance/conductance indication downward as described on 50ohm.", + "source": "https://50ohm.de/E_widerstand_ntc_ptc.html", + "confidence": 7 + }, + "EC111": { + "revision": 1, + "explanation": "A PTC thermistor has a positive temperature coefficient: as temperature rises, resistance rises. The matching symbol is the one with both temperature and resistance trend upward.", + "source": "https://50ohm.de/E_widerstand_ntc_ptc.html", + "confidence": 7 + }, + "EC112": { + "revision": 1, + "explanation": "A 10 percent tolerance on 5.6 kOhm is 0.56 kOhm. The possible range is 5.6 - 0.56 to 5.6 + 0.56 kOhm, or 5040 to 6160 Ohm.", + "source": "https://50ohm.de/NE_widerstand_toleranz.html", + "confidence": 8 + }, + "EC113": { + "revision": 1, + "explanation": "Green-blue-red is 56 times 100, so the nominal value is 5600 Ohm. Silver means 10 percent tolerance, giving 5040 to 6160 Ohm.", + "source": "https://50ohm.de/NE_widerstand_toleranz.html", + "confidence": 8 + }, + "EC114": { + "revision": 1, + "explanation": "Common three-digit SMD resistor marking uses the first digits as significant figures and the last digit as the power of ten multiplier.", + "source": "https://50ohm.de/E_widerstand_smd.html", + "confidence": 8 + }, + "EC115": { + "revision": 1, + "explanation": "The marking 103 means 10 followed by 3 zeros: 10 * 10^3 Ohm = 10000 Ohm = 10 kOhm.", + "source": "https://50ohm.de/E_widerstand_smd.html", + "confidence": 8 + }, + "EC116": { + "revision": 1, + "explanation": "The marking 221 means 22 followed by one zero: 22 * 10^1 Ohm = 220 Ohm.", + "source": "https://50ohm.de/E_widerstand_smd.html", + "confidence": 8 + }, + "EC117": { + "revision": 1, + "explanation": "The marking 223 means 22 followed by three zeros: 22 * 10^3 Ohm = 22000 Ohm = 22 kOhm.", + "source": "https://50ohm.de/E_widerstand_smd.html", + "confidence": 8 + }, + "EC201": { + "revision": 1, + "explanation": "An initially discharged capacitor charges quickly at first, then the voltage rise flattens as it approaches the supply voltage. That is the rising exponential charging curve.", + "source": "https://50ohm.de/EA_kondensator_1.html", + "confidence": 7 + }, + "EC202": { + "revision": 1, + "explanation": "A capacitor's AC reactance is inversely proportional to frequency. As frequency increases, an ideal capacitor's opposition to AC decreases.", + "source": "https://50ohm.de/EA_kondensator_1.html", + "confidence": 8 + }, + "EC203": { + "revision": 1, + "explanation": "For a plate capacitor, capacitance is proportional to plate area and dielectric constant, and inversely proportional to plate spacing. A larger spacing therefore reduces capacitance.", + "source": "https://50ohm.de/EA_kondensator_1.html", + "confidence": 8 + }, + "EC204": { + "revision": 1, + "explanation": "Increasing the plate distance puts the same plates farther apart, so the plate capacitor's capacitance falls.", + "source": "https://50ohm.de/EA_kondensator_1.html", + "confidence": 8 + }, + "EC205": { + "revision": 1, + "explanation": "Ideal plate-capacitor capacitance depends on geometry and dielectric material, not on the applied voltage.", + "source": "https://50ohm.de/EA_kondensator_1.html", + "confidence": 8 + }, + "EC206": { + "revision": 1, + "explanation": "A variable capacitor with rotor plates moving between fixed stator plates is a Drehkondensator; rotation changes the overlapping plate area and thus the capacitance.", + "source": "https://50ohm.de/EA_kondensator_1.html", + "confidence": 8 + }, + "EC207": { + "revision": 1, + "explanation": "Electrolytic capacitors are polarized because their oxide dielectric depends on the correct DC polarity; reversed polarity can damage them.", + "source": "https://50ohm.de/EA_kondensator_1.html", + "confidence": 8 + }, + "EC301": { + "revision": 1, + "explanation": "After DC is applied through a resistor, an inductor initially opposes the current change, so the voltage across it starts high and then decays toward zero.", + "source": "https://50ohm.de/EA_spule_1.html", + "confidence": 7 + }, + "EC302": { + "revision": 1, + "explanation": "The coil initially limits current because it opposes the sudden current change, so the lamp fed through the plain resistor lights first.", + "source": "https://50ohm.de/EA_spule_1.html", + "confidence": 8 + }, + "EC303": { + "revision": 1, + "explanation": "An ideal inductor's AC reactance is proportional to frequency, so its opposition to AC rises as frequency increases.", + "source": "https://50ohm.de/EA_spule_1.html", + "confidence": 8 + }, + "EC304": { + "revision": 1, + "explanation": "Any current-carrying conductor has a magnetic field and therefore some inductance, even if it is only a straight piece of wire.", + "source": "https://50ohm.de/E_spule_1.html", + "confidence": 8 + }, + "EC305": { + "revision": 1, + "explanation": "For the same winding, shortening the coil length increases inductance. Compressing the cylindrical coil in the length direction therefore raises L.", + "source": "https://50ohm.de/EA_spule_1.html", + "confidence": 8 + }, + "EC306": { + "revision": 1, + "explanation": "For the same turns and cross-section, inductance is inversely proportional to coil length. Doubling the length halves 12 microhenry to 6 microhenry.", + "source": "https://50ohm.de/EA_spule_1.html", + "confidence": 8 + }, + "EC307": { + "revision": 1, + "explanation": "Inductance is proportional to the square of the number of turns. Doubling the turns multiplies 12 microhenry by 4, giving 48 microhenry.", + "source": "https://50ohm.de/EA_spule_1.html", + "confidence": 8 + }, + "EC401": { + "revision": 1, + "explanation": "A 15:1 transformer ratio steps the 230 V primary down by 15. 230/15 is about 15.3 V, so the secondary is about 15 V.", + "source": "https://50ohm.de/E_uebertrager_1.html", + "confidence": 8 + }, + "EC402": { + "revision": 1, + "explanation": "If the primary has five times as many turns as the secondary, the secondary voltage is one fifth of the primary voltage. 230/5 = 46 V.", + "source": "https://50ohm.de/E_uebertrager_1.html", + "confidence": 8 + }, + "EC403": { + "revision": 1, + "explanation": "Turns ratio follows voltage ratio: 230/11.5 = 20. The secondary therefore has 600/20 = 30 turns.", + "source": "https://50ohm.de/E_uebertrager_1.html", + "confidence": 8 + }, + "EC404": { + "revision": 1, + "explanation": "The secondary voltage is four times the primary voltage, so the secondary must have four times the turns. 150 * 4 = 600 turns.", + "source": "https://50ohm.de/E_uebertrager_1.html", + "confidence": 8 + }, + "EC501": { + "revision": 1, + "explanation": "In reverse bias a normal diode blocks current except for a tiny leakage current, so it behaves like a high resistance.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 8 + }, + "EC502": { + "revision": 1, + "explanation": "A diode conducts mainly in one direction, so it can pass one half-cycle polarity and block the other; that is the basic rectifier function.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 8 + }, + "EC503": { + "revision": 1, + "explanation": "Germanium diodes have a lower forward threshold, roughly 0.2 to 0.4 V, while silicon diodes are typically around 0.6 to 0.8 V.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 8 + }, + "EC504": { + "revision": 1, + "explanation": "A Schottky diode uses a metal-semiconductor junction, giving a low forward voltage and very fast switching compared with ordinary pn diodes.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 8 + }, + "EC505": { + "revision": 1, + "explanation": "On the shown characteristic plot, curve 1 starts conducting at the lowest forward voltage near 0.2 V, which matches a Schottky diode.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC506": { + "revision": 1, + "explanation": "Curve 2 begins conducting around 0.2 to 0.4 V, the typical forward-threshold range for a germanium diode.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC507": { + "revision": 1, + "explanation": "Curve 3 starts its steep rise around 0.6 to 0.8 V, matching the usual silicon-diode forward threshold.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC508": { + "revision": 1, + "explanation": "Curve 4 has the highest forward threshold in the plot, around the LED range, so it represents a light-emitting diode.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC509": { + "revision": 1, + "explanation": "A silicon diode conducts when its anode is about 0.7 V more positive than its cathode. In the selected drawing, the right/anode side is 1.3 V and the left/cathode side is 0.6 V.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC510": { + "revision": 1, + "explanation": "Use the silicon-diode rule: anode about 0.7 V above cathode. The selected drawing has 0.3 V on the anode side and -0.4 V on the cathode side.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC511": { + "revision": 1, + "explanation": "Forward conduction depends on voltage difference, not whether the node voltages are positive. Here the anode is -1.3 V and the cathode is -2.0 V, so the anode is 0.7 V higher.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC512": { + "revision": 1, + "explanation": "The conducting silicon-diode case is the one with the anode about 0.7 V above the cathode. In the selected drawing, -3.0 V is 0.7 V higher than -3.7 V.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC513": { + "revision": 1, + "explanation": "A silicon diode becomes forward-biased when the anode is about 0.7 V above the cathode. 5.7 V at the anode and 5.0 V at the cathode meets that condition.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 8 + }, + "EC514": { + "revision": 1, + "explanation": "The circuit is a current-limited LED: the resistor sets the LED current and the diode symbol with outgoing arrows indicates light emission.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC515": { + "revision": 1, + "explanation": "The resistor must drop the remaining voltage: 5.0 V - 1.4 V = 3.6 V. At 20 mA, R = 3.6/0.020 = 180 Ohm.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 8 + }, + "EC516": { + "revision": 1, + "explanation": "The resistor drops 5.5 V - 1.75 V = 3.75 V. With 25 mA, R = 3.75/0.025 = 150 Ohm and P = 3.75 * 0.025 about 0.094 W, so 0.1 W is needed.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 8 + }, + "EC517": { + "revision": 1, + "explanation": "The bent cathode bar is the distinctive schematic mark for a Zener diode, used in reverse breakdown operation.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC518": { + "revision": 1, + "explanation": "A Zener diode is designed to operate in reverse breakdown at a defined voltage, making it useful for voltage stabilization.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 8 + }, + "EC519": { + "revision": 1, + "explanation": "The shown circuit puts a Zener diode across the output after a series resistor, the standard simple shunt voltage stabilizer arrangement.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC520": { + "revision": 1, + "explanation": "For positive output stabilization, the Zener diode is placed after the series resistor and reverse-biased across the output. That lets it clamp the output near its Zener voltage.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 7 + }, + "EC521": { + "revision": 1, + "explanation": "The resistor drops 13.8 V - 5 V = 8.8 V at 30 mA. R = 8.8/0.030 = 293 Ohm approximately.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 8 + }, + "EC522": { + "revision": 1, + "explanation": "The series resistor carries both Zener and load current: 25 mA + 20 mA = 45 mA. With a 4.7 V output, R = (13.8 - 4.7)/0.045 about 202 Ohm.", + "source": "https://50ohm.de/EA_diode_1.html", + "confidence": 8 + }, + "EC601": { + "revision": 1, + "explanation": "A transistor can be biased to switch fully on/off, to operate linearly as an amplifier, or in some cases to behave as a controllable resistance.", + "source": "https://50ohm.de/NEA_transistor_1.html", + "confidence": 8 + }, + "EC602": { + "revision": 1, + "explanation": "A transistor is built from semiconductor regions; the usual bipolar types use alternating n- and p-doped semiconductor zones.", + "source": "https://50ohm.de/NEA_transistor_1.html", + "confidence": 8 + }, + "EC603": { + "revision": 1, + "explanation": "In the practical current-control model, a small base current controls a much larger collector current; their ratio is the current gain.", + "source": "https://50ohm.de/NEA_transistor_1.html", + "confidence": 8 + }, + "EC604": { + "revision": 1, + "explanation": "Bipolar junction transistors are the NPN and PNP types. FET names such as MOS-FET or junction-FET belong to field-effect transistors, not bipolar transistors.", + "source": "https://50ohm.de/NEA_transistor_1.html", + "confidence": 8 + }, + "EC605": { + "revision": 2, + "explanation": "A bipolar transistor symbol has base, collector, and emitter terminals, with an emitter arrow; FET symbols use gate, drain, and source structures instead.", + "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "confidence": 7 + }, + "EC606": { + "revision": 2, + "explanation": "In an NPN transistor symbol the emitter arrow points outward, matching the common mnemonic 'NPN: Not Pointing iN'.", + "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "confidence": 7 + }, + "EC607": { + "revision": 2, + "explanation": "In a PNP transistor symbol the emitter arrow points inward toward the transistor body; 50ohm gives the mnemonic 'PNP: Pfeil Nach Platte'.", + "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "confidence": 7 + }, + "EC608": { + "revision": 1, + "explanation": "The three terminals of a bipolar transistor are emitter, base, and collector. Drain, source, and gate are FET terminal names.", + "source": "https://50ohm.de/NEA_transistor_1.html", + "confidence": 8 + }, + "EC609": { + "revision": 2, + "explanation": "The shown NPN symbol has the collector at terminal 1, the base at terminal 2, and the emitter with the arrow at terminal 3.", + "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "confidence": 7 + }, + "EC610": { + "revision": 2, + "explanation": "The base-emitter junction of a conducting silicon bipolar transistor is forward biased at about 0.6 V in the class-E model.", + "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "confidence": 8 + }, + "EC611": { + "revision": 1, + "explanation": "The emitter current is the sum of collector current and base current, so in the conducting state the emitter carries the largest current.", + "source": "https://50ohm.de/NEA_transistor_1.html", + "confidence": 8 + }, + "EC612": { + "revision": 2, + "explanation": "For an NPN transistor, collector current flows when the base is about 0.6 V above the emitter. 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", + "confidence": 7 + }, + "EC613": { + "revision": 2, + "explanation": "Only the voltage difference matters: for NPN, the base must be about 0.6 V above the emitter. Here -5.6 V is 0.6 V above -6.2 V, so the transistor conducts.", + "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "confidence": 7 + }, + "EC614": { + "revision": 2, + "explanation": "For a PNP transistor, collector current flows when the base is about 0.6 V below the emitter. 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", + "confidence": 7 + }, + "EC615": { + "revision": 2, + "explanation": "For PNP, the base-emitter voltage is negative when conducting: the base is about 0.6 V lower than the emitter. Here +5.6 V at the base and +6.2 V at the emitter satisfy that.", + "source": "https://50ohm.de/NEA_slide_nea_bauelemente.html", + "confidence": 7 + }, + "ED101": { + "revision": 1, + "explanation": "In a series voltage divider, voltage drops in the same ratio as resistance. If R1 is 5 times R2, then U1 is 5 times U2.", + "source": "https://50ohm.de/NE_spannungsteiler_1.html", + "confidence": 8 + }, + "ED102": { + "revision": 1, + "explanation": "In a series voltage divider, U1/U2 = R1/R2. If R1 is one sixth of R2, then U1 is one sixth of U2.", + "source": "https://50ohm.de/NE_spannungsteiler_1.html", + "confidence": 8 + }, + "ED103": { + "revision": 1, + "explanation": "Use the divider rule: U2 = U * R2/(R1 + R2). With 9 V, 10 kOhm, and 20 kOhm, U2 = 9 * 20/30 = 6.0 V.", + "source": "https://50ohm.de/NE_spannungsteiler_1.html", + "confidence": 8 + }, + "ED104": { + "revision": 1, + "explanation": "For two parallel resistors, Rg = R1*R2/(R1+R2). 100*400/(100+400) = 40000/500 = 80 Ohm.", + "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "confidence": 8 + }, + "ED105": { + "revision": 1, + "explanation": "For two parallel resistors, Rg = R1*R2/(R1+R2). 50*200/(50+200) = 10000/250 = 40 Ohm.", + "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "confidence": 8 + }, + "ED106": { + "revision": 1, + "explanation": "For n equal resistors in parallel, Rg = R/n. Therefore each resistor is R = n*Rg = 3*1.7 kOhm = 5.1 kOhm.", + "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "confidence": 8 + }, + "ED107": { + "revision": 1, + "explanation": "With three equal resistors, the allowed total power is the sum of the individual ratings when the load is shared. That gives 3*1 W = 3 W in both series and parallel arrangements.", + "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "confidence": 8 + }, + "ED108": { + "revision": 1, + "explanation": "R1 and R2 are in series, giving 500 + 500 = 1000 Ohm. That 1000 Ohm branch is in parallel with R3 = 1000 Ohm, so the total is 500 Ohm.", + "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "confidence": 7 + }, + "ED109": { + "revision": 1, + "explanation": "R1 and R2 first add in series: 500 Ohm + 1.5 kOhm = 2 kOhm. That is in parallel with R3 = 2 kOhm, so the result is 1 kOhm.", + "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "confidence": 7 + }, + "ED110": { + "revision": 1, + "explanation": "The two 1 kOhm resistors are parallel, so they reduce to 500 Ohm. In series with the remaining 500 Ohm, the total is 1 kOhm.", + "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "confidence": 7 + }, + "ED111": { + "revision": 1, + "explanation": "R2 and R3 are both 2 kOhm in parallel, giving 1 kOhm. Adding the series R1 of 1 kOhm gives 2 kOhm total.", + "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "confidence": 7 + }, + "ED112": { + "revision": 1, + "explanation": "R2 and R3 are parallel: 3 kOhm || 1.5 kOhm = 1 kOhm. Add the series R1 of 1 kOhm to get 2 kOhm.", + "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "confidence": 7 + }, + "ED113": { + "revision": 1, + "explanation": "R1, R2, and R3 are parallel: 10 kOhm || 2.5 kOhm || 500 Ohm = 400 Ohm. Adding the series 600 Ohm resistor gives 1 kOhm.", + "source": "https://50ohm.de/E_reihe_parallel_widerstand.html", + "confidence": 7 + }, + "ED114": { + "revision": 1, + "explanation": "Reduce the obvious groups step by step: 50 Ohm + 50 Ohm gives 100 Ohm, 100 Ohm in parallel with 100 Ohm gives 50 Ohm, then the remaining series parts total 250 Ohm.", + "source": "https://50ohm.de/NE_reihe_parallel_widerstandsnetz_1.html", + "confidence": 7 + }, + "ED115": { + "revision": 1, + "explanation": "Combine the clear series and parallel subgroups in stages; the network reduces to a final series sum of 550 Ohm.", + "source": "https://50ohm.de/NE_reihe_parallel_widerstandsnetz_1.html", + "confidence": 7 + }, + "ED116": { + "revision": 1, + "explanation": "After reducing the drawn subgroups, the remaining series values are 400 Ohm, 200 Ohm, 200 Ohm, and 150 Ohm. Their sum is 950 Ohm.", + "source": "https://50ohm.de/NE_reihe_parallel_widerstandsnetz_1.html", + "confidence": 7 + }, + "ED117": { + "revision": 1, + "explanation": "Parallel capacitances add directly. 0.1 uF = 100 nF and 50000 pF = 50 nF, so 100 + 150 + 50 = 300 nF = 0.3 uF.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "confidence": 8 + }, + "ED118": { + "revision": 1, + "explanation": "Parallel capacitors add directly after unit conversion: 22 nF + 0.033 uF (33 nF) + 15000 pF (15 nF) = 70 nF = 0.070 uF.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "confidence": 8 + }, + "ED119": { + "revision": 1, + "explanation": "For equal capacitors in series, Cg = C/n. Three 0.33 uF capacitors therefore give 0.33/3 = 0.110 uF.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "confidence": 8 + }, + "ED120": { + "revision": 1, + "explanation": "Convert 200000 nF to 200 uF. The series formula gives 1/Cg = 1/100 + 1/200 + 1/200, so Cg = 50 uF.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "confidence": 8 + }, + "ED121": { + "revision": 1, + "explanation": "C1 and C2 are equal 10 nF capacitors in series, so their equivalent is 5 nF. In parallel with C3 = 5 nF, the total is 10 nF.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "confidence": 7 + }, + "ED122": { + "revision": 1, + "explanation": "C2 and C3 are parallel, giving 1 uF + 1 uF = 2 uF. That is in series with C1 = 2 uF, so two equal 2 uF capacitors in series give 1.0 uF.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "confidence": 7 + }, + "ED123": { + "revision": 1, + "explanation": "C2 and C3 are parallel, so 4 nF + 4 nF = 8 nF. That 8 nF equivalent is in series with C1 = 8 nF, giving 4 nF.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "confidence": 7 + }, + "ED124": { + "revision": 1, + "explanation": "Convert C3 = 100000 pF to 100 nF. C2 and C3 are parallel, giving 200 nF; that is in series with C1 = 200 nF, so the total is 100 nF.", + "source": "https://50ohm.de/NEA_reihe_parallel_kondensator.html", + "confidence": 7 + }, + "ED201": { + "revision": 1, + "explanation": "The graph passes low frequencies and attenuates frequencies above the cutoff, which is the defining response of a low-pass filter.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED202": { + "revision": 1, + "explanation": "The graph attenuates low frequencies and passes higher frequencies after the cutoff, so it is a high-pass response.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED203": { + "revision": 1, + "explanation": "The curve passes only a middle frequency range and attenuates both low and high frequencies, which is a band-pass response.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED204": { + "revision": 1, + "explanation": "The curve passes frequencies on both sides but rejects a middle range around resonance, so it is a band-stop response.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED205": { + "revision": 1, + "explanation": "A series resonant circuit has minimum impedance at resonance because inductive and capacitive reactance cancel, giving the V-shaped impedance curve.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 8 + }, + "ED206": { + "revision": 1, + "explanation": "A parallel resonant circuit has maximum impedance at resonance, producing the peaked impedance curve shown.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 8 + }, + "ED207": { + "revision": 1, + "explanation": "At resonance a parallel LC circuit presents a very high impedance; away from resonance one branch becomes comparatively low impedance.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 8 + }, + "ED208": { + "revision": 1, + "explanation": "The circuit takes the output after a series resistor with a capacitor shunting high frequencies to ground, so low frequencies pass and high frequencies are attenuated: a low-pass filter.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED209": { + "revision": 1, + "explanation": "A series inductor followed by a shunt capacitor passes low frequencies: the inductor is low impedance at low frequency and the capacitor shunts high frequency components.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED210": { + "revision": 1, + "explanation": "For microphone audio low-pass filtering, the selected RC network uses capacitors to bypass high-frequency components while the wanted lower audio range remains at the output.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED211": { + "revision": 1, + "explanation": "A series capacitor followed by a resistor load is a high-pass: the capacitor blocks low-frequency components and passes higher-frequency components more easily.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED212": { + "revision": 1, + "explanation": "With a series capacitor and a shunt inductor, low frequencies are shunted through the inductor while higher frequencies pass through the capacitor path, so the circuit is a high-pass.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED213": { + "revision": 1, + "explanation": "The selected LC ladder has a series capacitor path with shunt inductors, the high-pass pattern: low frequencies are bypassed, higher frequencies are passed.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED214": { + "revision": 1, + "explanation": "A parallel resonant circuit placed in series with the signal path has high impedance at resonance and blocks that frequency, so it is a Sperrkreis.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED215": { + "revision": 1, + "explanation": "A series resonant LC branch connected across the signal path has low impedance at resonance and diverts that frequency away from the output, so it is a Saugkreis.", + "source": "https://50ohm.de/EA_schwingkreis_1.html", + "confidence": 7 + }, + "ED216": { + "revision": 1, + "explanation": "HF filters need low-loss, high-Q capacitors with small parasitic effects; ceramic and air capacitors are preferred over electrolytics.", + "source": "https://50ohm.de/EA_kondensator_1.html", + "confidence": 8 + }, + "ED301": { + "revision": 1, + "explanation": "A useful DC supply should keep its output voltage nearly constant under load; otherwise the connected radio stages see supply-voltage changes.", + "source": "https://50ohm.de/EA_spannungsquelle.html", + "confidence": 8 + }, + "ED302": { + "revision": 1, + "explanation": "Switch-mode supplies convert power at high switching frequency, allowing small transformers and heat sinks, so they are efficient, light, and compact.", + "source": "https://50ohm.de/NEA_schaltnetzteil_1.html", + "confidence": 8 + }, + "ED303": { + "revision": 1, + "explanation": "The high-frequency switching action can generate RF interference unless the supply is well filtered and shielded.", + "source": "https://50ohm.de/NEA_schaltnetzteil_1.html", + "confidence": 8 + }, + "ED304": { + "revision": 1, + "explanation": "The circuit is a single-diode half-wave rectifier. The load voltage contains only the conducting half-cycles, with the opposite half-cycles blocked by the diode.", + "source": "https://50ohm.de/EA_gleichrichter_1.html", + "confidence": 7 + }, + "ED401": { + "revision": 1, + "explanation": "Power gain means the output signal power is greater than the input signal power. That extra power must come from an external supply, not from the input signal alone.", + "source": "https://50ohm.de/NE_verstaerker.html", + "confidence": 8 + }, + "ED402": { + "revision": 1, + "explanation": "The shown transistor audio-stage topology is an NF amplifier; it is meant for low-frequency/audio signal amplification, not RF or IF selection.", + "source": "https://50ohm.de/NE_verstaerker.html", + "confidence": 7 + }, + "ED403": { + "revision": 1, + "explanation": "An HF power amplifier raises the transmitter's RF signal level to the desired output power before feeding the antenna system.", + "source": "https://50ohm.de/NE_verstaerker.html", + "confidence": 8 + }, + "ED501": { + "revision": 1, + "explanation": "An LC oscillator uses a tuned circuit made from an inductor L and capacitor C; that resonant circuit sets the oscillation frequency.", + "source": "https://50ohm.de/E_oszillatoren.html", + "confidence": 8 + }, + "ED502": { + "revision": 1, + "explanation": "The LC resonance frequency is inversely related to the square root of capacitance. If C increases, the oscillator frequency decreases.", + "source": "https://50ohm.de/E_oszillatoren.html", + "confidence": 8 + }, + "ED503": { + "revision": 1, + "explanation": "The LC resonance frequency rises when capacitance falls, because frequency is inversely related to sqrt(L*C).", + "source": "https://50ohm.de/E_oszillatoren.html", + "confidence": 8 + }, + "ED504": { + "revision": 1, + "explanation": "The LC resonance frequency is inversely related to the square root of inductance. If L increases, the oscillator frequency decreases.", + "source": "https://50ohm.de/E_oszillatoren.html", + "confidence": 8 + }, + "ED505": { + "revision": 1, + "explanation": "When inductance decreases, the LC product becomes smaller, so the resonant frequency becomes higher.", + "source": "https://50ohm.de/E_oszillatoren.html", + "confidence": 8 + }, + "ED506": { + "revision": 1, + "explanation": "In a crystal oscillator, the quartz crystal is the frequency-determining resonator.", + "source": "https://50ohm.de/E_oszillatoren.html", + "confidence": 8 + }, + "ED507": { + "revision": 1, + "explanation": "A quartz crystal's resonance changes much less with temperature and component tolerances than a simple LC circuit, so crystal oscillators are more frequency-stable.", + "source": "https://50ohm.de/E_oszillatoren.html", + "confidence": 8 + }, + "EE101": { + "revision": 1, + "explanation": "An unmodulated carrier is a steady sine wave with constant amplitude, frequency, and phase; the selected diagram shows that unchanged carrier.", + "source": "https://50ohm.de/E_unmodulierter_traeger.html", + "confidence": 7 + }, + "EE201": { + "revision": 1, + "explanation": "AM carries both sidebands plus carrier, while SSB suppresses the carrier and one sideband. Therefore SSB needs less than half the bandwidth of AM.", + "source": "https://50ohm.de/E_ssb_2.html", + "confidence": 8 + }, + "EE202": { + "revision": 1, + "explanation": "In SSB, only one translated sideband is transmitted, so the occupied RF bandwidth is essentially the same as the audio/NF bandwidth being sent.", + "source": "https://50ohm.de/E_ssb_2.html", + "confidence": 8 + }, + "EE203": { + "revision": 1, + "explanation": "USB places the audio component above the carrier. 21.250 MHz + 0.001 MHz = 21.251 MHz.", + "source": "https://50ohm.de/E_ssb_2.html", + "confidence": 8 + }, + "EE204": { + "revision": 1, + "explanation": "LSB places the audio component below the carrier and suppresses the carrier in ideal SSB. 3.650 MHz - 0.002 MHz = 3.648 MHz.", + "source": "https://50ohm.de/E_ssb_2.html", + "confidence": 8 + }, + "EE205": { + "revision": 2, + "explanation": "For SSB voice, RF output follows the audio drive level. Reducing the NF/audio amplitude reduces the modulated transmitter output power.", + "source": "https://50ohm.de/E_slide_e_modulation.html", + "confidence": 8 + }, + "EE206": { + "revision": 2, + "explanation": "Too little microphone gain gives too little audio drive to the SSB modulator, so the transmitter produces low output power.", + "source": "https://50ohm.de/E_slide_e_modulation.html", + "confidence": 8 + }, + "EE207": { + "revision": 1, + "explanation": "CW keys one carrier rather than transmitting a full speech spectrum, so its occupied bandwidth is smaller than both SSB voice and AM voice.", + "source": "https://50ohm.de/E_ssb_2.html", + "confidence": 8 + }, + "EE301": { + "revision": 1, + "explanation": "The shown waveform keeps amplitude essentially constant while the instantaneous carrier frequency changes, which identifies frequency modulation.", + "source": "https://50ohm.de/EA_fm_2.html", + "confidence": 7 + }, + "EE302": { + "revision": 1, + "explanation": "FM carries information in frequency deviation rather than amplitude, so amplitude noise has less direct effect than it does in SSB.", + "source": "https://50ohm.de/EA_fm_2.html", + "confidence": 8 + }, + "EE303": { + "revision": 1, + "explanation": "Vehicle electrical noise often appears as amplitude disturbance. FM is least affected because the receiver can limit amplitude and use frequency deviation instead.", + "source": "https://50ohm.de/EA_fm_2.html", + "confidence": 8 + }, + "EE304": { + "revision": 1, + "explanation": "In FM, a larger frequency deviation spreads the signal over a wider range of frequencies, increasing RF bandwidth.", + "source": "https://50ohm.de/EA_fm_2.html", + "confidence": 8 + }, + "EE305": { + "revision": 1, + "explanation": "Excessive FM bandwidth is reduced by lowering the deviation setting, because deviation directly determines how far the carrier moves from center frequency.", + "source": "https://50ohm.de/EA_fm_2.html", + "confidence": 8 + }, + "EE306": { + "revision": 1, + "explanation": "In FM, loudness is represented by the size of the carrier-frequency deviation, not by RF amplitude.", + "source": "https://50ohm.de/EA_fm_2.html", + "confidence": 8 + }, + "EE401": { + "revision": 1, + "explanation": "Bandwidth is occupied frequency range measured in hertz. Data rate is the amount of information transferred per time, measured in bit/s.", + "source": "https://50ohm.de/NEA_datenuebertragungsdrate.html", + "confidence": 8 + }, + "EE402": { + "revision": 1, + "explanation": "SSB translates the audio-frequency digimode signal to RF while preserving its narrow bandwidth, which is why modes such as FT8 or BPSK31 are sent through an SSB transmitter path.", + "source": "https://50ohm.de/NEA_digimode_ssb.html", + "confidence": 8 + }, + "EE403": { + "revision": 1, + "explanation": "With SSB, the RF bandwidth follows the bandwidth of the audio/NF signal. A 50 Hz audio signal therefore occupies about 50 Hz RF bandwidth.", + "source": "https://50ohm.de/NEA_digimode_ssb.html", + "confidence": 8 + }, + "EE404": { + "revision": 1, + "explanation": "A 2.4 kHz SSB passband can contain several much narrower digimode signals at different audio frequencies, and software can decode one or more of them.", + "source": "https://50ohm.de/NEA_digimode_ssb.html", + "confidence": 8 + }, + "EE405": { + "revision": 2, + "explanation": "Reporter networks collect received digimode spots by callsign. Sending a suitable signal such as WSPR and then searching the reporting platform shows where it was received.", + "source": "https://50ohm.de/NEA_slide_nea_digitale_uebertragungsverfahren.html", + "confidence": 8 + }, + "EE406": { + "revision": 1, + "explanation": "ASK changes the carrier amplitude between symbol states while frequency stays recognisably the same; the selected diagram shows those amplitude changes.", + "source": "https://50ohm.de/EA_ask_fsk_afsk.html", + "confidence": 7 + }, + "EE407": { + "revision": 1, + "explanation": "FSK changes between different carrier frequencies while keeping amplitude essentially constant; the selected diagram shows changing period/frequency.", + "source": "https://50ohm.de/EA_ask_fsk_afsk.html", + "confidence": 7 + }, + "EE408": { + "revision": 1, + "explanation": "In AFSK, frequency-shift keying is first generated as an audio-frequency signal, which then modulates an RF transmitter such as an FM, AM, or SSB rig.", + "source": "https://50ohm.de/NEA_afsk.html", + "confidence": 8 + }, + "EE409": { + "revision": 2, + "explanation": "TDMA separates users by time slots: signals take rapid turns on the same frequency rather than transmitting continuously at once.", + "source": "https://50ohm.de/NEA_vielfachzugriff.html", + "confidence": 8 + }, + "EE410": { + "revision": 2, + "explanation": "FDMA separates simultaneous signals by frequency, so users transmit at the same time but on different frequency channels.", + "source": "https://50ohm.de/NEA_vielfachzugriff.html", + "confidence": 8 + }, + "EE411": { + "revision": 2, + "explanation": "CDMA lets signals share time and frequency by applying different spreading codes that the receiver uses to separate them.", + "source": "https://50ohm.de/NEA_vielfachzugriff.html", + "confidence": 8 + }, + "EE412": { + "revision": 1, + "explanation": "In a packet-switched network, packets can be forwarded through intermediate stations or routers when the two endpoints cannot reach each other directly.", + "source": "https://50ohm.de/NEA_paketvermittelte_netzwerke.html", + "confidence": 8 + }, + "EE413": { + "revision": 1, + "explanation": "The IP address plus subnet mask defines which addresses are on the same local subnet and are reachable directly without routing.", + "source": "https://50ohm.de/NEA_paketvermittelte_netzwerke.html", + "confidence": 8 + }, + "EE414": { + "revision": 1, + "explanation": "IP is a network protocol, not something limited to the public Internet, so it can also be used in amateur-radio networks such as HAMNET.", + "source": "https://50ohm.de/NEA_paketvermittelte_netzwerke.html", + "confidence": 8 + }, + "EE415": { + "revision": 1, + "explanation": "SSTV sends still pictures slowly, while ATV is amateur television with moving pictures and much larger bandwidth needs.", + "source": "https://50ohm.de/NEA_digimode_ssb.html", + "confidence": 8 + }, + "EF101": { + "revision": 1, + "explanation": "The circuit is a detector receiver: the tuned circuit selects the station and the diode recovers the audio envelope without an active oscillator or amplifier.", + "source": "https://50ohm.de/NE_detektorempf%C3%A4nger.html", + "confidence": 7 + }, + "EF102": { + "revision": 1, + "explanation": "A superhet converts received signals to a fixed IF, so fixed filters can provide much better selectivity than a tuned-radio-frequency receiver.", + "source": "https://50ohm.de/E_ueberlagerungsempfaenger_einfachsuper_1.html", + "confidence": 8 + }, + "EF201": { + "revision": 1, + "explanation": "A mixer mainly produces the sum and absolute difference: 31.7 MHz + 21 MHz = 52.7 MHz and |31.7 MHz - 21 MHz| = 10.7 MHz.", + "source": "https://50ohm.de/E_mischer.html", + "confidence": 8 + }, + "EF202": { + "revision": 1, + "explanation": "Mixer products are the sum and absolute difference: 38.7 MHz + 28 MHz = 66.7 MHz and |38.7 MHz - 28 MHz| = 10.7 MHz.", + "source": "https://50ohm.de/E_mischer.html", + "confidence": 8 + }, + "EF203": { + "revision": 1, + "explanation": "The desired mixer products are sum and difference, so 30 MHz and 39 MHz produce 69 MHz and 9 MHz.", + "source": "https://50ohm.de/E_mischer.html", + "confidence": 8 + }, + "EF204": { + "revision": 1, + "explanation": "A mixer gives sum and absolute difference: 145 MHz + 136 MHz = 281 MHz and |145 MHz - 136 MHz| = 9 MHz.", + "source": "https://50ohm.de/E_mischer.html", + "confidence": 8 + }, + "EF205": { + "revision": 1, + "explanation": "The wanted first-order mixer products are the sum and difference, here 281 MHz and 9 MHz.", + "source": "https://50ohm.de/E_mischer.html", + "confidence": 8 + }, + "EF206": { + "revision": 1, + "explanation": "Mixers generate many RF products, so good shielding is needed to keep unwanted signals from being radiated or coupled into other stages.", + "source": "https://50ohm.de/E_mischer.html", + "confidence": 8 + }, + "EF207": { + "revision": 1, + "explanation": "An oscillator should be enclosed in a grounded metal shield so its RF energy is not unintentionally radiated.", + "source": "https://50ohm.de/NE_oszillatoren.html", + "confidence": 8 + }, + "EF208": { + "revision": 1, + "explanation": "In direct conversion the IF is audio, so the local oscillator must be very close to the received RF frequency.", + "source": "https://50ohm.de/E_ueberlagerungsempfaenger_einfachsuper_1.html", + "confidence": 8 + }, + "EF209": { + "revision": 1, + "explanation": "A BFO inserts the missing carrier needed to demodulate CW or SSB, making those signals audible.", + "source": "https://50ohm.de/NEA_bfo_1.html", + "confidence": 8 + }, + "EF210": { + "revision": 1, + "explanation": "Narrow receiver bandwidth rejects nearby unwanted signals, which is exactly high selectivity.", + "source": "https://50ohm.de/E_trennschaerfe_1.html", + "confidence": 8 + }, + "EF211": { + "revision": 1, + "explanation": "AGC changes receiver gain as the RF input varies, keeping the demodulated audio level more constant.", + "source": "https://50ohm.de/NE_agc_1.html", + "confidence": 8 + }, + "EF212": { + "revision": 1, + "explanation": "AGC stands for Automatic Gain Control, the automatic receiver gain regulation used to reduce level swings.", + "source": "https://50ohm.de/NE_agc_1.html", + "confidence": 8 + }, + "EF213": { + "revision": 1, + "explanation": "Noise Reduction tries to distinguish wanted signal from noise and suppress the noise component in the received signal.", + "source": "https://50ohm.de/NE_noise_reduction.html", + "confidence": 8 + }, + "EF214": { + "revision": 1, + "explanation": "A noise blanker blanks short impulse disturbances, unlike a notch filter or AGC which target different problems.", + "source": "https://50ohm.de/NE_noise_reduction.html", + "confidence": 8 + }, + "EF215": { + "revision": 1, + "explanation": "A notch filter is a narrow rejection filter, so it can suppress interference at one small frequency range while leaving the rest mostly unchanged.", + "source": "https://50ohm.de/NE_notchfilter.html", + "confidence": 8 + }, + "EF216": { + "revision": 1, + "explanation": "A notch response is recognized by a narrow dip in an otherwise passed band; the correct diagram shows that sharp rejection notch.", + "source": "https://50ohm.de/NE_notchfilter.html", + "confidence": 7 + }, + "EF217": { + "revision": 1, + "explanation": "An attenuator reduces the RF input level before the receiver front end, preventing overload from strong signals.", + "source": "https://50ohm.de/NE_vorverstaerker_daempfungsglied.html", + "confidence": 8 + }, + "EF218": { + "revision": 1, + "explanation": "A UHF preamplifier should be at the antenna so it amplifies the signal before feed-line loss degrades the noise figure.", + "source": "https://50ohm.de/NE_vorverstaerker_daempfungsglied.html", + "confidence": 8 + }, + "EF219": { + "revision": 1, + "explanation": "A 9600-port bypasses audio filtering and takes receive data directly after the FM demodulator, which is point 4 in the shown chain.", + "source": "https://50ohm.de/NEA_9600_port.html", + "confidence": 7 + }, + "EF301": { + "revision": 1, + "explanation": "The multiplier chain is reversed by division: 145.2 MHz / 2 / 3 / 2 = 12.1 MHz.", + "source": "https://50ohm.de/NE_frequenzvervielfacher_1.html", + "confidence": 8 + }, + "EF302": { + "revision": 1, + "explanation": "Work backward through the multipliers in the diagram: 21.360 MHz / 3 / 2 = 3.560 MHz.", + "source": "https://50ohm.de/NE_frequenzvervielfacher_1.html", + "confidence": 8 + }, + "EF303": { + "revision": 1, + "explanation": "Work forward through the multiplier chain: 3.51 MHz x 2 x 2 = 14.04 MHz at output a.", + "source": "https://50ohm.de/NE_frequenzvervielfacher_1.html", + "confidence": 8 + }, + "EF304": { + "revision": 1, + "explanation": "Temperature changes alter oscillator L/C values gradually, so a VFO under changing temperature slowly drifts in frequency.", + "source": "https://50ohm.de/NE_oszillatoren.html", + "confidence": 8 + }, + "EF305": { + "revision": 1, + "explanation": "ALC protects the transmit chain from overdrive by reducing the signal amplitude before the power amplifier when level is too high.", + "source": "https://50ohm.de/NEA_alc.html", + "confidence": 8 + }, + "EF306": { + "revision": 2, + "explanation": "A dynamic compressor raises quiet speech parts relative to loud ones, compressing the speech dynamic range.", + "source": "https://50ohm.de/NE_slide_ne_modulation.html", + "confidence": 8 + }, + "EF307": { + "revision": 1, + "explanation": "A speech microphone amplifier should pass roughly 300 Hz to 3 kHz and reject lower and higher frequencies, matching the band-pass graph.", + "source": "https://50ohm.de/NE_verstaerker.html", + "confidence": 7 + }, + "EF308": { + "revision": 1, + "explanation": "Intelligible SSB speech needs only about 2.5 to 3 kHz of audio bandwidth, so about 2.5 kHz is the minimum matching answer.", + "source": "https://50ohm.de/NE_verstaerker.html", + "confidence": 8 + }, + "EF309": { + "revision": 1, + "explanation": "For 9600-baud FM data the signal should bypass speech audio filters and enter directly at the FM modulator, point 2 in the transmitter diagram.", + "source": "https://50ohm.de/NEA_9600_port.html", + "confidence": 7 + }, + "EF310": { + "revision": 1, + "explanation": "An SSB speech filter only needs the voice sideband width; practical SSB generation commonly uses about 2.4 kHz.", + "source": "https://50ohm.de/E_ssb_2.html", + "confidence": 8 + }, + "EF401": { + "revision": 1, + "explanation": "Transmitter output power is measured directly at the transmitter output before tuners, filters, feed lines, or other accessories change it.", + "source": "https://50ohm.de/E_senderausgangsleistung.html", + "confidence": 8 + }, + "EF402": { + "revision": 1, + "explanation": "For SSB the relevant PEP is measured at the transmitter output using a steady one- or two-tone drive, not with an unmodulated carrier at the antenna.", + "source": "https://50ohm.de/E_senderausgangsleistung.html", + "confidence": 8 + }, + "EF403": { + "revision": 1, + "explanation": "SSB carries information in signal amplitude and phase, so its final stage must be linear to avoid distorting the waveform.", + "source": "https://50ohm.de/EA_verstaerker.html", + "confidence": 8 + }, + "EF404": { + "revision": 1, + "explanation": "Changing the final amplifier bias can change linearity, so the transmitter must then be checked for harmonic output.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EF405": { + "revision": 1, + "explanation": "The transmitter supply should be well decoupled against RF so RF energy cannot couple into the power wiring or other stages.", + "source": "https://50ohm.de/EA_verstaerker.html", + "confidence": 8 + }, + "EF501": { + "revision": 1, + "explanation": "A transverter converts both directions: on receive it downconverts the higher band to the transceiver band, and on transmit it upconverts the transceiver signal.", + "source": "https://50ohm.de/NE_transverter_1.html", + "confidence": 8 + }, + "EF502": { + "revision": 1, + "explanation": "A transverter changes bands by mixing the input signal with a local oscillator and filtering the wanted product.", + "source": "https://50ohm.de/NE_transverter_1.html", + "confidence": 8 + }, + "EF503": { + "revision": 1, + "explanation": "The block diagram shows receive and transmit frequency conversion around a VHF transceiver, which is a transverter for the 2 m band.", + "source": "https://50ohm.de/NE_transverter_1.html", + "confidence": 7 + }, + "EF504": { + "revision": 1, + "explanation": "The diagram upconverts a VHF transmit signal to the 13 cm range, so it is a 13 cm converter placed before a VHF transmitter.", + "source": "https://50ohm.de/NE_transverter_1.html", + "confidence": 7 + }, + "EF505": { + "revision": 1, + "explanation": "In a GHz transverter the oscillator is multiplied, so any oscillator frequency error is multiplied too and can be too large for SSB satellite operation.", + "source": "https://50ohm.de/NE_transverter_1.html", + "confidence": 8 + }, + "EF601": { + "revision": 1, + "explanation": "Digital signal processing first converts the analog input with an A/D converter and later reconstructs an analog output with a D/A converter.", + "source": "https://50ohm.de/NEA_digitale_signalverarbeitung_einleitung.html", + "confidence": 8 + }, + "EF602": { + "revision": 1, + "explanation": "A digital filter can only process digital samples, so the analog input signal must first be digitized by A/D conversion.", + "source": "https://50ohm.de/NEA_digitale_signalverarbeitung_einleitung.html", + "confidence": 8 + }, + "EF603": { + "revision": 1, + "explanation": "SDR means Software Defined Radio: at least part of the receiver or transceiver signal processing is implemented in software.", + "source": "https://50ohm.de/NEA_digitale_signalverarbeitung_einleitung.html", + "confidence": 8 + }, + "EG101": { + "revision": 1, + "explanation": "A loop made from three equal wire sections forms a triangle, so it is the delta-loop form of a full-wave loop antenna.", + "source": "https://50ohm.de/EA_antennenformen_2.html", + "confidence": 8 + }, + "EG102": { + "revision": 1, + "explanation": "A wire antenna can have many lengths if an appropriate matching network is used; resonance and feed impedance change with length.", + "source": "https://50ohm.de/NE_antenne_laenge_resonanz.html", + "confidence": 8 + }, + "EG103": { + "revision": 1, + "explanation": "The diagram shows a wire fed from one end through a simple matching unit, which is an end-fed antenna with a basic matching network.", + "source": "https://50ohm.de/E_antennenformen_2.html", + "confidence": 7 + }, + "EG104": { + "revision": 1, + "explanation": "The shown end-fed wire with a tuned Fuchs matching circuit is the characteristic Fuchs antenna arrangement.", + "source": "https://50ohm.de/E_antennenformen_2.html", + "confidence": 7 + }, + "EG105": { + "revision": 1, + "explanation": "A magnetic loop is small compared with wavelength, about lambda/10 circumference, and its near field is dominated by a strong magnetic component.", + "source": "https://50ohm.de/EA_antennenformen_2.html", + "confidence": 8 + }, + "EG106": { + "revision": 1, + "explanation": "Common HF transmitting antennas include long wire, Yagi-Uda, dipole, Windom, and delta-loop; horn, patch, and parabolic antennas are mainly higher-frequency forms.", + "source": "https://50ohm.de/EA_antennenformen_2.html", + "confidence": 8 + }, + "EG107": { + "revision": 2, + "explanation": "For 80 m HF operation, dipoles, delta loops, and W3DZZ trap dipoles are practical wire antennas; parabolic, cross-Yagi, and trap-sleeve forms are not suitable choices here.", + "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "confidence": 8 + }, + "EG108": { + "revision": 1, + "explanation": "A 5/8-wave vertical is chosen because its length gives better antenna gain than a quarter-wave mobile vertical.", + "source": "https://50ohm.de/E_antennenformen_2.html", + "confidence": 8 + }, + "EG109": { + "revision": 1, + "explanation": "The wavelength is 300 / 28.5 = 10.53 m, and 5/8 of that is about 6.58 m.", + "source": "https://50ohm.de/NE_antenne_laenge_resonanz.html", + "confidence": 8 + }, + "EG110": { + "revision": 1, + "explanation": "A folded dipole is essentially a flattened full-wave loop, so the total wire length is one wavelength.", + "source": "https://50ohm.de/NE_antenne_laenge_resonanz.html", + "confidence": 8 + }, + "EG111": { + "revision": 1, + "explanation": "A simple Yagi-Uda has the longer reflector behind the driven element and a shorter director in front, giving the order reflector, driven element, director.", + "source": "https://50ohm.de/NE_yagi_uda_2.html", + "confidence": 7 + }, + "EG112": { + "revision": 2, + "explanation": "For a directional HF antenna, placing it high and far from neighboring equipment reduces field strength at the neighbor and therefore coupling risk.", + "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "confidence": 8 + }, + "EG113": { + "revision": 1, + "explanation": "Microwave dish antennas use a paraboloid reflector plus a feed antenna; the feed illuminates the reflector that forms the narrow beam.", + "source": "https://50ohm.de/EA_parabolspiegel_1.html", + "confidence": 8 + }, + "EG114": { + "revision": 1, + "explanation": "Dish gain improves when the reflector is many wavelengths across; at least about five wavelengths is the suitable choice for high gain.", + "source": "https://50ohm.de/EA_parabolspiegel_1.html", + "confidence": 8 + }, + "EG201": { + "revision": 1, + "explanation": "The shortening factor compares wave speed on the line or wire with wave speed in vacuum, so it is the velocity ratio.", + "source": "https://50ohm.de/E_verkuerzungsfaktor_1.html", + "confidence": 8 + }, + "EG202": { + "revision": 1, + "explanation": "For wire antennas the usual shortening correction is about 0.95, meaning about 95 percent of the free-space calculated length.", + "source": "https://50ohm.de/E_verkuerzungsfaktor_1.html", + "confidence": 8 + }, + "EG203": { + "revision": 1, + "explanation": "At a dipole end charge and voltage are high while current goes to zero, so the ends are voltage maxima and current nodes.", + "source": "https://50ohm.de/NEA_strom_spannung_speisung_1.html", + "confidence": 8 + }, + "EG204": { + "revision": 1, + "explanation": "Current feeding means high current and low voltage at the feed point, a current maximum and voltage node, which gives low impedance.", + "source": "https://50ohm.de/NE_strom_spannung_speisung_1.html", + "confidence": 8 + }, + "EG205": { + "revision": 1, + "explanation": "Voltage feeding is the opposite case: high voltage and nearly zero current at the feed point, so the feed point is high impedance.", + "source": "https://50ohm.de/NE_strom_spannung_speisung_1.html", + "confidence": 8 + }, + "EG206": { + "revision": 1, + "explanation": "A half-wave dipole fed in the middle has its current maximum at the center, so it is current-fed on its fundamental frequency.", + "source": "https://50ohm.de/NE_strom_spannung_speisung_1.html", + "confidence": 8 + }, + "EG207": { + "revision": 1, + "explanation": "A center-fed half-wave dipole high above ground has a free-space feed impedance near 73 Ohm, so the rounded answer is 75 Ohm.", + "source": "https://50ohm.de/E_fusspunktimpedanz_1.html", + "confidence": 8 + }, + "EG208": { + "revision": 1, + "explanation": "Ground interaction changes a center-fed half-wave dipole impedance with height, typically over about 40 to 90 Ohm.", + "source": "https://50ohm.de/E_fusspunktimpedanz_1.html", + "confidence": 8 + }, + "EG209": { + "revision": 1, + "explanation": "A straight center-fed half-wave dipole is in the same practical impedance range as the height-dependent value, about 40 to 90 Ohm.", + "source": "https://50ohm.de/E_fusspunktimpedanz_1.html", + "confidence": 8 + }, + "EG210": { + "revision": 1, + "explanation": "A folded dipole approximately quadruples the feed impedance of a normal dipole, giving about 240 to 300 Ohm.", + "source": "https://50ohm.de/E_fusspunktimpedanz_1.html", + "confidence": 8 + }, + "EG211": { + "revision": 1, + "explanation": "A ground-plane is roughly half a dipole against ground, and sloping radials bring its feed impedance into the 30 to 50 Ohm range.", + "source": "https://50ohm.de/E_fusspunktimpedanz_1.html", + "confidence": 8 + }, + "EG212": { + "revision": 1, + "explanation": "In a Yagi-Uda antenna the feed is applied to the driven element, called the Strahler; reflector and directors are parasitic elements.", + "source": "https://50ohm.de/NE_yagi_uda_2.html", + "confidence": 8 + }, + "EG213": { + "revision": 1, + "explanation": "A ground-plane is unbalanced because the radial side is at earth or counterpoise potential; dipoles, folded dipoles, and Yagis are balanced antenna forms.", + "source": "https://50ohm.de/EA_antennenformen_2.html", + "confidence": 8 + }, + "EG214": { + "revision": 1, + "explanation": "A half-wave dipole pattern has two equal broad lobes perpendicular to the wire, matching the symmetric two-lobed diagram.", + "source": "https://50ohm.de/NE_antennenformen_2.html", + "confidence": 7 + }, + "EG215": { + "revision": 1, + "explanation": "The shown two-lobed pattern perpendicular to the wire is the typical radiation pattern of a half-wave dipole.", + "source": "https://50ohm.de/NE_antennenformen_2.html", + "confidence": 7 + }, + "EG216": { + "revision": 1, + "explanation": "The nearly circular horizontal pattern around the vertical radiator is typical of a ground-plane antenna viewed from above.", + "source": "https://50ohm.de/EA_antennenformen_2.html", + "confidence": 7 + }, + "EG217": { + "revision": 1, + "explanation": "A large forward lobe with a smaller rear lobe indicates directional gain, so the diagram is for a directional antenna.", + "source": "https://50ohm.de/EA_antennenformen_2.html", + "confidence": 7 + }, + "EG218": { + "revision": 1, + "explanation": "A Yagi-Uda radiation pattern has a strong main lobe toward the directors and smaller rear or side lobes, matching the shown diagram.", + "source": "https://50ohm.de/NE_yagi_uda_2.html", + "confidence": 7 + }, + "EG219": { + "revision": 1, + "explanation": "A vertical half-wave antenna radiates mainly perpendicular to the vertical element, giving a low elevation or flat radiation angle.", + "source": "https://50ohm.de/E_antennenformen_2.html", + "confidence": 8 + }, + "EG220": { + "revision": 1, + "explanation": "The suffix dBi means gain in dB relative to an isotropic radiator, the ideal antenna radiating equally in all directions.", + "source": "https://50ohm.de/NE_antennengewinn.html", + "confidence": 8 + }, + "EG221": { + "revision": 1, + "explanation": "dBd is referenced to a half-wave dipole, which is 2.15 dB above isotropic; 5 dBd + 2.15 dB = 7.15 dBi.", + "source": "https://50ohm.de/NE_antennengewinn.html", + "confidence": 8 + }, + "EG222": { + "revision": 1, + "explanation": "Antenna polarization is defined by the electric field orientation in the main radiation direction relative to the earth surface.", + "source": "https://50ohm.de/E_polarisation_2.html", + "confidence": 8 + }, + "EG223": { + "revision": 2, + "explanation": "Putting the transmitting antenna outdoors reduces coupling into house wiring and nearby electrical installations.", + "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "confidence": 8 + }, + "EG301": { + "revision": 1, + "explanation": "A line's characteristic impedance is set by its conductor geometry and dielectric; in the HF range it is roughly constant and does not depend on the load connected at the end.", + "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "confidence": 8 + }, + "EG302": { + "revision": 1, + "explanation": "Good coaxial cable confines the RF field inside the shield in normal use, reducing unwanted radiation between station devices.", + "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "confidence": 8 + }, + "EG303": { + "revision": 1, + "explanation": "N connectors are designed for 50 Ohm operation into the GHz range and are suitable for higher power and voltage than SMA or BNC in this comparison.", + "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "confidence": 8 + }, + "EG304": { + "revision": 1, + "explanation": "A feed line is unbalanced when the two conductors are not equivalent, as in coax where the inner conductor and shield have different shapes and potentials.", + "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "confidence": 8 + }, + "EG305": { + "revision": 1, + "explanation": "Open parallel-wire feed line avoids much dielectric loss and can withstand high voltages better than coaxial cable.", + "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "confidence": 8 + }, + "EG306": { + "revision": 1, + "explanation": "Running RF feed lines directly beside mains leads can couple RF into the power wiring, so a shared cable duct can worsen interference risk.", + "source": "https://50ohm.de/E_uebertragungsleitungen_2.html", + "confidence": 8 + }, + "EG307": { + "revision": 1, + "explanation": "Cable losses in dB are added as positive attenuation values; the shown station layout sums to 5 dB of cable loss.", + "source": "https://50ohm.de/EA_kabeldaempfung_1.html", + "confidence": 7 + }, + "EG308": { + "revision": 1, + "explanation": "With SWR 1 there is no reflection; 100 W reduced to 50 W is a factor of 2 loss, which corresponds to 3 dB attenuation.", + "source": "https://50ohm.de/EA_kabeldaempfung_1.html", + "confidence": 8 + }, + "EG309": { + "revision": 1, + "explanation": "Only one quarter of the power remains, so the loss factor is 4; a power factor of 4 is about 6 dB.", + "source": "https://50ohm.de/EA_kabeldaempfung_1.html", + "confidence": 8 + }, + "EG310": { + "revision": 1, + "explanation": "Only one tenth of the power remains, so the loss factor is 10; a power factor of 10 is 10 dB.", + "source": "https://50ohm.de/EA_kabeldaempfung_1.html", + "confidence": 8 + }, + "EG311": { + "revision": 1, + "explanation": "Cable attenuation scales with length for the same cable and frequency: 20 dB per 100 m times 20/100 gives 4 dB.", + "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "confidence": 8 + }, + "EG312": { + "revision": 1, + "explanation": "The cable-loss chart gives RG58 at 145 MHz as about 20 dB per 100 m, and the question length is exactly 100 m.", + "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "confidence": 8 + }, + "EG313": { + "revision": 1, + "explanation": "RG58 is about 20 dB per 100 m at 145 MHz; for 15 m the attenuation is 20 x 15/100 = 3 dB.", + "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "confidence": 8 + }, + "EG314": { + "revision": 1, + "explanation": "The chart value for RG174 at 145 MHz is about 40 dB per 100 m; for 50 m this is 40 x 50/100 = 20 dB.", + "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "confidence": 8 + }, + "EG315": { + "revision": 1, + "explanation": "The chart gives about 7 dB per 100 m for the 12.7 mm PE-foam cable at 435 MHz; 40 m gives 7 x 40/100 = 2.8 dB.", + "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "confidence": 8 + }, + "EG316": { + "revision": 1, + "explanation": "The chart gives about 20.5 dB per 100 m for the 10.3 mm PE-foam cable at 1296 MHz; 40 m gives about 8.2 dB.", + "source": "https://50ohm.de/E_kabeldaempfung_1.html", + "confidence": 8 + }, + "EG401": { + "revision": 2, + "explanation": "For SWR 3 the reflection coefficient is (3 - 1)/(3 + 1) = 0.5, so reflected power is 0.5 squared = 25 percent of 100 W, i.e. 25 W.", + "source": "https://50ohm.de/NEA_swr.html", + "confidence": 8 + }, + "EG402": { + "revision": 2, + "explanation": "SWR 3 gives voltage reflection coefficient 0.5; power reflection is 0.5 squared, so 25 percent of forward power is reflected.", + "source": "https://50ohm.de/NEA_swr.html", + "confidence": 8 + }, + "EG403": { + "revision": 2, + "explanation": "If SWR 3 reflects 25 percent of the forward power, the remaining 75 percent is delivered to the load.", + "source": "https://50ohm.de/NEA_swr.html", + "confidence": 8 + }, + "EG404": { + "revision": 1, + "explanation": "The current on the outside of the coax shield is the common-mode or mantle current, called Mantelstrom in the diagram.", + "source": "https://50ohm.de/NE_mantelwellen_1.html", + "confidence": 7 + }, + "EG405": { + "revision": 1, + "explanation": "Mantle waves make the coax shield radiate or receive as part of the antenna, which can disturb other devices and worsen the station's own reception.", + "source": "https://50ohm.de/NE_mantelwellen_1.html", + "confidence": 8 + }, + "EG406": { + "revision": 1, + "explanation": "A balanced dipole fed directly with unbalanced coax can drive common-mode current on the shield, distorting the radiation pattern and creating mantle waves.", + "source": "https://50ohm.de/NE_mantelwellen_1.html", + "confidence": 8 + }, + "EG407": { + "revision": 2, + "explanation": "A balun connects a balanced antenna such as a dipole to an unbalanced feed line such as coax while suppressing common-mode current.", + "source": "https://50ohm.de/NE_mantelwellen_1.html", + "confidence": 8 + }, + "EG408": { + "revision": 2, + "explanation": "Coax turns on a ferrite core form a common-mode choke, increasing impedance for mantle currents and therefore damping mantle waves.", + "source": "https://50ohm.de/NE_mantelwellen_1.html", + "confidence": 7 + }, + "EG501": { + "revision": 2, + "explanation": "EIRP is antenna input power multiplied by antenna gain in the chosen direction, with the gain referenced to an isotropic radiator.", + "source": "https://life.itu.int/radioclub/rr/art1.pdf", + "confidence": 9 + }, + "EG502": { + "revision": 2, + "explanation": "First subtract losses from transmitter power to get power at the antenna, then multiply by antenna gain referenced to an isotropic radiator.", + "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "confidence": 8 + }, + "EG503": { + "revision": 2, + "explanation": "26 dBi is a gain factor of about 10^2.6 = 398; 0.25 W times 398 is about 100 W EIRP.", + "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "confidence": 8 + }, + "EG504": { + "revision": 2, + "explanation": "36 dBi is a gain factor of about 10^3.6 = 3981; 5 W times 3981 is about 20000 W EIRP.", + "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "confidence": 8 + }, + "EG505": { + "revision": 2, + "explanation": "The net isotropic gain is 11 dBi - 1 dB = 10 dB, a factor of 10, so 100 W becomes 1000 W EIRP.", + "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "confidence": 8 + }, + "EG506": { + "revision": 2, + "explanation": "A dipole has 2.15 dBi gain, factor 1.64, and the cable loss is also factor 1.64; they cancel, leaving 75 W EIRP.", + "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "confidence": 8 + }, + "EG507": { + "revision": 2, + "explanation": "10 dB cable loss reduces 100 W to 10 W at the dipole; dipole gain is factor 1.64 relative to isotropic, giving 16.4 W EIRP.", + "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "confidence": 8 + }, + "EG508": { + "revision": 2, + "explanation": "5 dBd equals 7.15 dBi; after 2 dB cable loss the net gain is 5.15 dB, factor about 3.28, so 5 W becomes 16.4 W EIRP.", + "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "confidence": 8 + }, + "EG509": { + "revision": 2, + "explanation": "11 dBd equals 13.15 dBi; minus 1 dB cable loss gives 12.15 dB, factor about 16.4, and 0.6 W times that is about 9.8 W.", + "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "confidence": 8 + }, + "EG510": { + "revision": 2, + "explanation": "0 dBd equals 2.15 dBi; after 1.5 dB cable loss the net gain is 0.65 dB, factor about 1.17, so 8.5 W becomes about 9.9 W.", + "source": "https://50ohm.de/NE_aequivalente_isotrope_strahlungsleistung_eirp_1.html", + "confidence": 8 + }, + "EG511": { + "revision": 1, + "explanation": "BEMFV notification starts at 10 W EIRP. A 5.15 dBi antenna has factor about 3.28, so transmitter power must be at most about 10 / 3.28 = 3 W.", + "source": "https://www.gesetze-im-internet.de/bemfv/__9.html", + "confidence": 9 + }, + "EH101": { + "revision": 1, + "explanation": "HF long-distance propagation uses sky waves refracted by ionized, electrically charged regions of the ionosphere.", + "source": "https://50ohm.de/E_ionosphaere_2.html", + "confidence": 8 + }, + "EH102": { + "revision": 1, + "explanation": "The important HF DX regions are mainly the F regions, which lie roughly from 130 km up to about 450 km altitude.", + "source": "https://50ohm.de/E_ionosphaere_2.html", + "confidence": 8 + }, + "EH103": { + "revision": 1, + "explanation": "The F2 region persists high in the ionosphere and is the main refracting region for long-distance HF communication.", + "source": "https://50ohm.de/E_ionosphaere_2.html", + "confidence": 8 + }, + "EH104": { + "revision": 1, + "explanation": "At night the D region absorption largely disappears, and 80 m DX is then mainly enabled by F2-region refraction.", + "source": "https://50ohm.de/E_ionosphaere_2.html", + "confidence": 8 + }, + "EH105": { + "revision": 1, + "explanation": "The D region is strongly ionized by daylight and absorbs lower HF, especially 80 m and 160 m, causing strong daytime attenuation.", + "source": "https://50ohm.de/E_ionosphaere_2.html", + "confidence": 8 + }, + "EH106": { + "revision": 1, + "explanation": "Sporadic-E occurs as unusually ionized patches in the E region and can support upper-HF to VHF propagation in summer.", + "source": "https://50ohm.de/E_ionosphaere_2.html", + "confidence": 8 + }, + "EH107": { + "revision": 1, + "explanation": "Solar activity follows the sunspot cycle, whose average period is about 11 years.", + "source": "https://50ohm.de/E_ionosphaere_2.html", + "confidence": 8 + }, + "EH201": { + "revision": 1, + "explanation": "The dead zone is between the end of ground-wave coverage and the first point where the sky wave returns to earth.", + "source": "https://50ohm.de/E_tote_zone_1.html", + "confidence": 8 + }, + "EH202": { + "revision": 1, + "explanation": "Where ground wave and sky wave overlap, phase differences can make the received field strength vary, producing fading.", + "source": "https://50ohm.de/NE_fading.html", + "confidence": 8 + }, + "EH203": { + "revision": 1, + "explanation": "Signal weakening from overlap and interference of ground and sky waves is called fading.", + "source": "https://50ohm.de/NE_fading.html", + "confidence": 8 + }, + "EH204": { + "revision": 1, + "explanation": "MUF means Maximum Usable Frequency, the highest frequency still refracted back for the wanted path.", + "source": "https://50ohm.de/NE_muf_luf_1.html", + "confidence": 8 + }, + "EH205": { + "revision": 1, + "explanation": "At sunspot maximum solar UV and X-ray output are high, increasing ionization especially in the F region.", + "source": "https://50ohm.de/E_ionosphaere_2.html", + "confidence": 8 + }, + "EH206": { + "revision": 1, + "explanation": "More free electrons in the F2 region allow higher frequencies to be refracted back, so the MUF rises.", + "source": "https://50ohm.de/NE_muf_luf_1.html", + "confidence": 8 + }, + "EH207": { + "revision": 1, + "explanation": "To use frequencies above the current MUF, the refracting region needs stronger ionization so it can bend those higher frequencies back.", + "source": "https://50ohm.de/NE_muf_luf_1.html", + "confidence": 8 + }, + "EH208": { + "revision": 1, + "explanation": "Skip distance depends strongly on takeoff angle: a flatter radiation angle produces a longer hop, while a steeper angle returns sooner.", + "source": "https://50ohm.de/E_sprungdistanz_1.html", + "confidence": 8 + }, + "EH209": { + "revision": 1, + "explanation": "LUF is limited mainly by absorption, and lower HF absorption is controlled by the ionization level of the D region.", + "source": "https://50ohm.de/NE_muf_luf_1.html", + "confidence": 8 + }, + "EH210": { + "revision": 1, + "explanation": "During the day the D region absorbs low HF strongly, so 160 m and 80 m sky-wave signals are weak for worldwide communication.", + "source": "https://50ohm.de/E_ionosphaere_2.html", + "confidence": 8 + }, + "EH211": { + "revision": 1, + "explanation": "On 160 m in daytime, D-region absorption prevents useful sky-wave propagation, so propagation is mainly by ground wave.", + "source": "https://50ohm.de/E_bodenwelle.html", + "confidence": 8 + }, + "EH212": { + "revision": 1, + "explanation": "HF ground waves follow the earth beyond the optical horizon, but their attenuation increases at higher frequencies.", + "source": "https://50ohm.de/E_bodenwelle.html", + "confidence": 8 + }, + "EH213": { + "revision": 1, + "explanation": "The greyline is the twilight zone near sunrise and sunset where D-region absorption is reduced while higher-layer refraction can remain useful.", + "source": "https://50ohm.de/NE_greyline.html", + "confidence": 8 + }, + "EH214": { + "revision": 1, + "explanation": "A solar flare can abruptly increase D-region ionization and absorb HF sky waves; this shortwave fadeout is the Moegel-Dellinger effect.", + "source": "https://50ohm.de/E_moegel_dellinger_effekt.html", + "confidence": 8 + }, + "EH215": { + "revision": 1, + "explanation": "The Moegel-Dellinger effect causes a temporary loss or severe impairment of HF sky-wave propagation.", + "source": "https://50ohm.de/E_moegel_dellinger_effekt.html", + "confidence": 8 + }, + "EH216": { + "revision": 1, + "explanation": "Long path means the signal travels in the direction opposite the shortest bearing to the other station, around the longer side of the earth.", + "source": "https://50ohm.de/EA_langer_kurzer_weg_1.html", + "confidence": 8 + }, + "EH217": { + "revision": 1, + "explanation": "For Germany to VK, long path points away from the direct route and reaches Australia via the opposite direction, over South America.", + "source": "https://50ohm.de/EA_langer_kurzer_weg_1.html", + "confidence": 8 + }, + "EH218": { + "revision": 1, + "explanation": "Short-skip paths under 1000 km on 10 m are produced by refraction in localized sporadic-E ionization patches.", + "source": "https://50ohm.de/NE_sporadic_e_2.html", + "confidence": 8 + }, + "EH219": { + "revision": 1, + "explanation": "At sunspot maximum the F region is strongly ionized, so the 10 m band can support worldwide daytime contacts even with low power.", + "source": "https://50ohm.de/E_ionosphaere_2.html", + "confidence": 8 + }, + "EH301": { + "revision": 1, + "explanation": "The troposphere is the lower atmospheric layer where weather processes occur.", + "source": "https://50ohm.de/NE_troposphaere_2.html", + "confidence": 8 + }, + "EH302": { + "revision": 1, + "explanation": "VHF/UHF over-horizon propagation can occur when waves are bent, reflected, or scattered by tropospheric regions with different temperature and density.", + "source": "https://50ohm.de/NE_troposphaere_2.html", + "confidence": 8 + }, + "EH303": { + "revision": 1, + "explanation": "VHF long-distance contacts mainly use tropospheric propagation effects rather than HF-style ionospheric sky-wave propagation.", + "source": "https://50ohm.de/NE_troposphaere_2.html", + "confidence": 8 + }, + "EH304": { + "revision": 1, + "explanation": "Sporadic-E is refraction by locally limited, unusually highly ionized regions inside the E layer.", + "source": "https://50ohm.de/NE_sporadic_e_2.html", + "confidence": 8 + }, + "EH305": { + "revision": 2, + "explanation": "Aurora makes CW tone quality rough and unstable, so the report uses R and S plus A for Aurora instead of a normal tone rating.", + "source": "https://50ohm.de/E_slide_e_wellenausbreitung.html", + "confidence": 8 + }, + "EI101": { + "revision": 1, + "explanation": "Voltage is measured across a component, so the meter is connected in parallel; high input resistance prevents the meter from loading the circuit.", + "source": "https://50ohm.de/E_strom_spannung_messung_2.html", + "confidence": 8 + }, + "EI102": { + "revision": 1, + "explanation": "To use Ohm's law for a resistor, current must be measured in series through it and voltage in parallel across it.", + "source": "https://50ohm.de/E_strom_spannung_messung_2.html", + "confidence": 7 + }, + "EI103": { + "revision": 1, + "explanation": "The pointer is at 29 percent of full scale; on the 10 V range that is 0.29 x 10 V = 2.9 V.", + "source": "https://50ohm.de/NEA_zeigerinstrumente_ablesen.html", + "confidence": 7 + }, + "EI104": { + "revision": 1, + "explanation": "On the 300 V range the same pointer position corresponds to about 29 percent of full scale, so 0.29 x 300 V is about 88 V.", + "source": "https://50ohm.de/NEA_zeigerinstrumente_ablesen.html", + "confidence": 7 + }, + "EI201": { + "revision": 1, + "explanation": "A VNA measures frequency-dependent impedance and reflection behavior, so it is suited to finding resonances and impedances of tuned circuits and antennas.", + "source": "https://50ohm.de/NEA_vna_1.html", + "confidence": 8 + }, + "EI202": { + "revision": 1, + "explanation": "Resonance can be calculated from measured L and C or found directly by sweeping the circuit with a VNA.", + "source": "https://50ohm.de/NEA_vna_1.html", + "confidence": 8 + }, + "EI203": { + "revision": 1, + "explanation": "A vector network analyzer directly measures complex impedance, including resistance, reactance, and reflection/SWR quantities.", + "source": "https://50ohm.de/NEA_vna_1.html", + "confidence": 8 + }, + "EI204": { + "revision": 1, + "explanation": "Impedance measurement is a core VNA use because it compares voltage/current or incident/reflected waves over frequency.", + "source": "https://50ohm.de/NEA_vna_1.html", + "confidence": 8 + }, + "EI205": { + "revision": 1, + "explanation": "A VNA must be calibrated with the measurement setup so its reference plane and systematic errors are corrected before use.", + "source": "https://50ohm.de/NEA_vna_1.html", + "confidence": 8 + }, + "EI206": { + "revision": 1, + "explanation": "Open and short should reflect almost all power, giving very high SWR, while a matched load should show SWR near 1.", + "source": "https://50ohm.de/NEA_vna_1.html", + "confidence": 8 + }, + "EI301": { + "revision": 2, + "explanation": "The displayed sine period spans 8 divisions; at 0.5 ms per division the period is 8 x 0.5 ms = 4 ms.", + "source": "https://50ohm.de/NE_oszilloskop_1.html", + "confidence": 7 + }, + "EI302": { + "revision": 2, + "explanation": "The period is 4 ms, so frequency is 1 / 0.004 s = 250 Hz.", + "source": "https://50ohm.de/NE_oszilloskop_1.html", + "confidence": 8 + }, + "EI303": { + "revision": 2, + "explanation": "Pulse duration is read from the middle of the rising edge to the middle of the falling edge; the shown interval is 200 microseconds.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 7 + }, + "EI304": { + "revision": 2, + "explanation": "Audio distortion changes the waveform shape, and an oscilloscope displays waveform shape directly.", + "source": "https://50ohm.de/E_slide_e_strom_spannung_widerstand_leistung_energie.html", + "confidence": 8 + }, + "EI401": { + "revision": 2, + "explanation": "An SWR meter measures the match between feed line and load, so in transmitter use it indicates antenna-system matching.", + "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "confidence": 8 + }, + "EI402": { + "revision": 2, + "explanation": "The instrument for showing the match between a UHF transmitter and its feed line is an SWR meter.", + "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "confidence": 8 + }, + "EI403": { + "revision": 2, + "explanation": "In transmit operation SWR is measured with an SWR bridge that compares forward and reflected power on the line.", + "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "confidence": 8 + }, + "EI404": { + "revision": 2, + "explanation": "To judge the antenna itself, the SWR meter should be as close to the antenna as possible, between antenna cable and antenna.", + "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "confidence": 8 + }, + "EI405": { + "revision": 2, + "explanation": "To check whether the whole antenna system is well matched to the transmitter, the SWR meter belongs at the transmitter output, point 1.", + "source": "https://50ohm.de/NE_slide_ne_antennen_uebertragungsleitungen.html", + "confidence": 7 + }, + "EI501": { + "revision": 1, + "explanation": "An unmodulated RF signal has a single stable frequency, which a frequency counter can count directly.", + "source": "https://50ohm.de/NE_frequenzmessung_1.html", + "confidence": 8 + }, + "EI502": { + "revision": 1, + "explanation": "The marked digit is in the 10^3 Hz position of the counter display, so its place value is one kilohertz.", + "source": "https://50ohm.de/NE_frequenzmessung_1.html", + "confidence": 7 + }, + "EI503": { + "revision": 1, + "explanation": "In this display the marked digit is in the 10 Hz position, so its place value is ten hertz.", + "source": "https://50ohm.de/NE_frequenzmessung_1.html", + "confidence": 7 + }, + "EI504": { + "revision": 1, + "explanation": "A 10:1 prescaler divides the input by 10 before counting, so the real frequency is 10 x 14.5625 MHz = 145.625 MHz.", + "source": "https://50ohm.de/NE_frequenzmessung_1.html", + "confidence": 8 + }, + "EJ101": { + "revision": 1, + "explanation": "Conducted RF interference enters equipment through attached leads such as mains, antenna, or speaker cables; that is Einströmung.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ102": { + "revision": 1, + "explanation": "Radiated RF entering through poor enclosure shielding is Einstrahlung, distinct from conducted entry via cables.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ103": { + "revision": 1, + "explanation": "Even a clean wanted signal can overload nearby receiver stages or otherwise influence them, so the issue is overload or disturbing influence, not spurious emission.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ104": { + "revision": 1, + "explanation": "Lower transmitter power lowers field strength and coupling risk, so use only the minimum needed for satisfactory communication.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ105": { + "revision": 1, + "explanation": "In dense residential areas during TV viewing hours, the practical interference-reduction step is to transmit with no more power than needed for reliable communication.", + "source": "https://50ohm.de/NE_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ106": { + "revision": 1, + "explanation": "A high-gain 432 MHz antenna pointed at a TV receive antenna can create a very strong local signal and overload the TV receiver input.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ107": { + "revision": 1, + "explanation": "Receiver overload drives input stages out of their normal range, reducing effective sensitivity or even blocking reception.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ108": { + "revision": 1, + "explanation": "A nearly closed metal enclosure provides RF shielding by enclosing the circuitry in a conductive shell.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ109": { + "revision": 1, + "explanation": "A parallel nearby HF antenna can inductively or capacitively couple RF current into the 230 V mains wiring.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ110": { + "revision": 1, + "explanation": "Running the 80 m wire at right angles to the row of houses avoids long parallel coupling to building wiring and neighboring installations.", + "source": "https://50ohm.de/E_standortwahl.html", + "confidence": 8 + }, + "EJ111": { + "revision": 1, + "explanation": "A separate RF earth for transmitting antennas helps keep RF currents out of house wiring and therefore lowers in-house interference risk.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ112": { + "revision": 1, + "explanation": "LED lamps with mains-connected electronics can be susceptible to RF influence, unlike simple thermal or motor loads in the alternatives.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ113": { + "revision": 1, + "explanation": "Strong RF can be rectified by nonlinear semiconductor junctions in an audio power stage, producing audible noise even when the stereo is nominally off.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ114": { + "revision": 1, + "explanation": "If RF is entering the audio power stage through speaker leads, shielding those leads reduces the conducted RF path.", + "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EJ115": { + "revision": 1, + "explanation": "A shielded intercom cable reduces RF pickup on the wiring that otherwise conducts the interfering signal into the door-phone electronics.", + "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EJ116": { + "revision": 1, + "explanation": "A DVB-T2 input should pass UHF TV frequencies while rejecting the much lower 28 MHz amateur signal, so a high-pass filter is appropriate.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ117": { + "revision": 1, + "explanation": "For HF interference in a TV antenna lead, use the high-pass filter: it rejects low HF while passing the higher TV bands.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 7 + }, + "EJ118": { + "revision": 1, + "explanation": "A mantle-wave choke raises impedance for common-mode RF on the outside of the coax shield, suppressing those RF interference currents.", + "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EJ119": { + "revision": 1, + "explanation": "If 144 MHz RF is induced as common-mode current on the broadcast receiver coax, a mantle-wave choke before the receiver reduces that current.", + "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EJ120": { + "revision": 1, + "explanation": "Intermodulation creates phantom signals from two or more strong signals; removing one participating signal removes the product.", + "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EJ121": { + "revision": 1, + "explanation": "Corroded metal contacts are nonlinear and can rectify or mix nearby transmitter signals, creating unwanted products that disturb TV reception.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ122": { + "revision": 1, + "explanation": "The first useful step is to check whether the disturbance actually coincides in time with your transmissions.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ123": { + "revision": 1, + "explanation": "A room antenna gives poor shielding and selectivity against strong local RF; an outdoor TV antenna improves wanted signal and allows better filtering.", + "source": "https://50ohm.de/E_slide_e_sender.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EJ124": { + "revision": 1, + "explanation": "After cooperative mitigation attempts fail, the proper next step is to ask the responsible Bundesnetzagentur field office to examine the situation.", + "source": "https://50ohm.de/E_stoerungen_elektronischer_geraete_1.html", + "confidence": 8 + }, + "EJ201": { + "revision": 1, + "explanation": "A pure sine wave contains only one frequency component; non-sinusoidal carriers contain harmonics that can cause interference.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EJ202": { + "revision": 1, + "explanation": "Harmonics are unwanted multiples of the wanted RF frequency, so an harmonic filter is used to reduce them.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EJ203": { + "revision": 1, + "explanation": "A low-pass filter passes the wanted fundamental output while attenuating higher-frequency harmonics.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EJ204": { + "revision": 1, + "explanation": "Between transmitter and antenna, a low-pass filter is best for reducing harmonic radiation above the operating frequency.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EJ205": { + "revision": 1, + "explanation": "A UHF transmitter's harmonics are at still higher frequencies, so a following low-pass filter attenuates them while passing the wanted UHF signal.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EJ206": { + "revision": 1, + "explanation": "The correct circuit is the low-pass output filter, with series inductors and shunt capacitors arranged to pass the fundamental and shunt harmonics.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 7 + }, + "EJ207": { + "revision": 1, + "explanation": "A harmonic-reduction filter should pass the HF operating range and roll off higher frequencies, i.e. a low-pass characteristic.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 7 + }, + "EJ208": { + "revision": 1, + "explanation": "For an HF multiband transmitter, the output filter should pass all HF bands while attenuating frequencies above them, so the wide low-pass curve is best.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 7 + }, + "EJ209": { + "revision": 1, + "explanation": "Unwanted-emission power is assessed at the transmitter output including normally used inline devices such as the SWR meter and any low-pass filter.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EJ210": { + "revision": 1, + "explanation": "Keeping SSB occupied bandwidth to at most about 2.7 kHz limits spillover onto adjacent frequencies.", + "source": "https://50ohm.de/E_ssb_2.html", + "confidence": 8 + }, + "EJ211": { + "revision": 1, + "explanation": "SSB speech audio above about 3 kHz would widen the RF sideband unnecessarily, increasing adjacent-channel interference risk.", + "source": "https://50ohm.de/E_ssb_2.html", + "confidence": 8 + }, + "EJ212": { + "revision": 1, + "explanation": "For FM AFSK, occupied bandwidth rises with frequency deviation, so lowering audio drive or deviation reduces the transmitted bandwidth.", + "source": "https://50ohm.de/EA_fm_2.html", + "confidence": 8 + }, + "EJ213": { + "revision": 1, + "explanation": "Overdriving a power amplifier makes it nonlinear, creating distortion products and a high level of unwanted emissions.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EJ214": { + "revision": 1, + "explanation": "An overdriven SSB linear amplifier produces intermodulation products that spread into neighboring frequencies.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EJ215": { + "revision": 1, + "explanation": "Too much microphone gain overdrives the SSB transmit chain and creates splatter affecting nearby stations.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EJ216": { + "revision": 1, + "explanation": "Poor frequency stability can make the transmitter drift, potentially moving the emission outside authorized band limits.", + "source": "https://50ohm.de/NE_unerwuenschte_aussendungen_2.html", + "confidence": 8 + }, + "EJ217": { + "revision": 1, + "explanation": "If ALC acts during SSB digital modes, it can distort the audio/RF envelope and create unwanted products on neighboring frequencies.", + "source": "https://50ohm.de/NEA_digimode_ssb.html", + "confidence": 8 + }, + "EJ218": { + "revision": 1, + "explanation": "The audio drive for FT8, JS8, PSK31, and similar modes should be low enough that ALC does not engage, avoiding distortion and splatter.", + "source": "https://50ohm.de/NEA_digimode_ssb.html", + "confidence": 8 + }, + "EJ219": { + "revision": 1, + "explanation": "If ALC is causing interference in SSB digital operation, reduce the audio input level so the transmitter is no longer driven into ALC action.", + "source": "https://50ohm.de/NEA_digimode_ssb.html", + "confidence": 8 + }, + "EK101": { + "revision": 1, + "explanation": "RF energy absorption in the human body depends on frequency, including penetration depth and resonance effects, so exposure limits are frequency-dependent.", + "source": "https://50ohm.de/E_personenschutzabstand_grenzwerte.html", + "confidence": 8 + }, + "EK102": { + "revision": 1, + "explanation": "The 26th BImSchV uses different time references: Annex 1b values are RMS-averaged over 6 minutes, Annex 1a values are short-term RMS values, and Annex 3 uses instantaneous peak limits for pulsed fields.", + "source": "https://www.gesetze-im-internet.de/bimschv_26/BJNR196600996.html", + "confidence": 9 + }, + "EK103": { + "revision": 1, + "explanation": "For active body aids, the relevant protection criterion is the maximum instantaneous field value, not a 3- or 6-minute average.", + "source": "https://50ohm.de/E_personenschutzabstand_grenzwerte.html", + "confidence": 8 + }, + "EK104": { + "revision": 1, + "explanation": "13 dBd is 15.15 dBi, a factor about 32.7; 6 W therefore gives about 196 W EIRP, well above the 10 W EIRP amateur-station threshold requiring proof/notification duties.", + "source": "https://www.gesetze-im-internet.de/bemfv/__8.html", + "confidence": 9 + }, + "EK105": { + "revision": 1, + "explanation": "At 80 m the 3.65 m result lies in the reactive near field, where the far-field approximation is invalid, so measurement, simulation, or near-field calculation is needed.", + "source": "https://50ohm.de/E_naeherungsformel_1.html", + "confidence": 8 + }, + "EK106": { + "revision": 1, + "explanation": "The far-field approximation is invalid below roughly lambda/(2*pi); 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", + "confidence": 8 + }, + "EK107": { + "revision": 2, + "explanation": "When the safety distance is calculated from the antenna field, the distance must be maintained from every radiating point of the antenna, not only the feed point.", + "source": "https://50ohm.de/NEA_slide_nea_personenschutzabstand.html", + "confidence": 8 + }, + "EK108": { + "revision": 1, + "explanation": "Convert 7.5 dBd to 9.65 dBi, subtract 1.5 dB cable loss for 8.15 dB net gain, then use d = sqrt(30 x EIRP) / 28 V/m; the result is about 5.0 m.", + "source": "https://50ohm.de/E_naeherungsformel_1.html", + "confidence": 8 + }, + "EK201": { + "revision": 1, + "explanation": "Microwave antennas can concentrate high fields in a narrow beam, so people should not stay in the direct beam path of transmitting antennas.", + "source": "https://50ohm.de/NE_strahlengang_aufenthalt.html", + "confidence": 8 + }, + "EK202": { + "revision": 1, + "explanation": "Transmitting antennas can have high RF voltages on their conductors; touching them can cause burns and other RF voltage injuries.", + "source": "https://50ohm.de/E_slide_e_sicherheit.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EK203": { + "revision": 1, + "explanation": "Power-supply capacitors can remain charged after the mains plug is removed, so opening disconnected equipment can still expose you to electric shock.", + "source": "https://50ohm.de/NEA_slide_nea_sicherheit.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EK204": { + "revision": 1, + "explanation": "A fuse is a safety component matched to current and trip speed; after repair it must be replaced with the same current rating and same fast characteristic.", + "source": "https://50ohm.de/E_sicherungen.html", + "confidence": 8 + }, + "EK205": { + "revision": 1, + "explanation": "For a 3-core mains cable the standard colors are PE green-yellow, live conductor brown, and neutral blue.", + "source": "https://50ohm.de/E_spannungsquelle.html", + "confidence": 8 + }, + "EK206": { + "revision": 1, + "explanation": "Ungrounded wire antennas can accumulate static charge from weather such as rain or hail, creating a safety hazard.", + "source": "https://50ohm.de/E_slide_e_sicherheit.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EK207": { + "revision": 1, + "explanation": "High-value bleed resistors drain static charge to the station earth while their high resistance avoids significantly affecting RF operation.", + "source": "https://50ohm.de/NE_slide_ne_sicherheit.html?print-pdf=&showNotes=true", + "confidence": 8 + }, + "EK208": { + "revision": 1, + "explanation": "Bonding all antenna coax shields together and to the main earthing bar prevents dangerous potential differences between coax systems.", + "source": "https://50ohm.de/NE_slide_ne_sicherheit.html", + "confidence": 8 + }, + "EK209": { + "revision": 1, + "explanation": "The current Class E material states that an existing building earthing system may be used for antenna earthing, so no separate electrode or BNetzA approval is required for this answer.", + "source": "https://50ohm.de/NE_blitzerdung.html", + "confidence": 8 + }, + "EK210": { + "revision": 1, + "explanation": "VDE 0855-300 requires a solid earthing conductor, with example minimum cross sections of 16 mm2 copper, 25 mm2 aluminium, or 50 mm2 steel.", + "source": "https://50ohm.de/NE_blitzerdung.html", + "confidence": 8 + }, + "EK211": { + "revision": 1, + "explanation": "Connecting an antenna mast to an existing lightning protection system changes that system and must be included in the lightning protection concept by a qualified specialist.", + "source": "https://50ohm.de/NE_blitzerdung.html", + "confidence": 8 + }, "NA101": { "revision": 2, "explanation": "Cutting at $2/3$ of 20 m gives a $13.33$ m piece; the remaining $1/3$ is $6.67$ m.",