General exam question G4E04
Subelement G4, AMATEUR RADIO PRACTICES· Group G4E
Why should DC power for a 100-watt HF transceiver not be supplied by a vehicle’s auxiliary power socket?
- A.The socket is not wired with an RF-shielded power cable
- B.The socket’s wiring may be inadequate for the current drawn by the transceiver (correct answer)
- C.The DC polarity of the socket is reversed from the polarity of modern HF transceivers
- D.Drawing more than 50 watts from this socket could cause the engine to overheat
WhyDC power for a 100-watt HF transceiver should not come from a vehicle's auxiliary power socket because that socket's wiring may be inadequate for the current the transceiver draws. A vehicle's auxiliary power socket and its wiring are sized for light accessory loads, not the sustained high current a 100-watt HF transceiver draws, so using it risks overheating that wiring or an inadequate voltage drop under load, answer B. The socket isn't specifically RF-shielded or reverse-polarity by design in a way relevant here, and the 50-watt overheating claim in D isn't the real concern, wiring gauge is.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2023-2027 NCVEC Element 3 pool (public domain); the explanation above is original writing, see our methodology.
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