Extra exam question E7C08
Subelement E7, PRACTICAL CIRCUITS· Group E7C
Which of the following is most frequently used as a band-pass or notch filter in VHF and UHF transceivers?
- A.A Sallen-Key filter
- B.A helical filter (correct answer)
- C.A swinging choke filter
- D.A finite impulse response filter
WhyA helical filter is most frequently used as a band-pass or notch filter in VHF and UHF transceivers. Helical filters, coils wound on a form inside a shielded, resonant cavity-like enclosure, are the type most frequently used as band-pass or notch filters in VHF and UHF transceivers, offering good selectivity in a compact package at these frequencies, answer B. Sallen-Key filters are an active audio-frequency filter topology, swinging choke filters are a power-supply component, and finite impulse response filters are a digital signal processing technique, none of them is the typical VHF/UHF hardware filter this question describes.
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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