Extra exam question E4D03
Subelement E4, AMATEUR PRACTICES· Group E4D
What creates intermodulation interference between two repeaters in close proximity?
- A.The output signals cause feedback in the final amplifier of one or both transmitters
- B.The output signals mix in the final amplifier of one or both transmitters (correct answer)
- C.The input frequencies are harmonically related
- D.The output frequencies are harmonically related
WhyIntermodulation interference between two nearby repeaters is created when their output signals mix in the final amplifier of one or both transmitters. Intermodulation interference between two nearby repeaters typically arises when each transmitter's output signal finds its way into the other's final amplifier stage and the two signals mix there, generating spurious products at sum and difference frequencies, answer B. It isn't caused by feedback in the final amplifier, and it doesn't require the input or output frequencies to be harmonically related, ordinary nonlinear mixing of two unrelated frequencies is enough to produce intermod products.
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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