Extra exam question E4D04
Subelement E4, AMATEUR PRACTICES· Group E4D
Which of the following is used to reduce or eliminate intermodulation interference in a repeater caused by a nearby transmitter?
- A.A band-pass filter in the feed line between the transmitter and receiver
- B.A properly terminated circulator at the output of the repeater’s transmitter (correct answer)
- C.Utilizing a Class C final amplifier
- D.Utilizing a Class D final amplifier
WhyA properly terminated circulator at the output of a repeater's transmitter reduces or eliminates intermodulation interference caused by a nearby transmitter. A properly terminated circulator placed at a repeater transmitter's output helps prevent a nearby transmitter's signal from getting back into that transmitter's final amplifier and mixing there, since the circulator routes energy in one direction and absorbs reflected or intruding signals in a matched termination, reducing intermodulation interference, answer B. A band-pass filter in the feed line addresses a different part of the interference path, and Class C or Class D final amplifier topology isn't what's used to solve this particular problem.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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