General exam question G4A01
Subelement G4, AMATEUR RADIO PRACTICES· Group G4A
What is the purpose of the notch filter found on many HF transceivers?
- A.To restrict the transmitter voice bandwidth
- B.To reduce interference from carriers in the receiver passband (correct answer)
- C.To eliminate receiver interference from impulse noise sources
- D.To remove interfering splatter generated by signals on adjacent frequencies
WhyA notch filter reduces interference from carriers sitting inside the receiver's passband. A notch filter is a narrow, tunable band-reject filter aimed at a single unwanted carrier or heterodyne tone sitting inside the receiver's passband, letting the operator null it out without losing the rest of the audio, answer B. It isn't a bandwidth-limiting filter (A), doesn't target impulse noise (C, that's a noise blanker's job), and doesn't address adjacent-channel splatter (D), which is a transmitter-side problem, not something a receive notch fixes.
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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