Extra exam question E7E01
Subelement E7, PRACTICAL CIRCUITS· Group E7E
Which of the following can be used to generate FM phone signals?
- A.Balanced modulation of the audio amplifier
- B.Reactance modulation of a local oscillator (correct answer)
- C.Reactance modulation of the final amplifier
- D.Balanced modulation of a local oscillator
WhyFM phone signals can be generated by reactance modulation of a local oscillator. FM phone signals can be generated by reactance modulation of a local oscillator, varying a reactive element (like a varactor) connected to the oscillator so the audio signal directly shifts the oscillator's frequency, producing FM, answer B. Balanced modulation is a technique associated with generating suppressed-carrier AM/SSB signals, not FM, and reactance modulation applied to a final amplifier, rather than the oscillator itself, isn't how FM generation actually works.
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.