General exam question G4A04
Subelement G4, AMATEUR RADIO PRACTICES· Group G4A
What is the effect on plate current of the correct setting of a vacuum-tube RF power amplifier’s TUNE control?
- A.A pronounced peak
- B.A pronounced dip (correct answer)
- C.No change will be observed
- D.A slow, rhythmic oscillation
WhyThe correct TUNE setting on a vacuum-tube RF power amplifier is recognized by a pronounced dip in plate current. As a vacuum-tube RF power amplifier's plate tank circuit is tuned through resonance, the tank's impedance rises to its peak, which pulls plate current down to a minimum, so the correct TUNE setting is recognized by a pronounced dip in plate current, answer B. Plate current doesn't peak, stay flat, or oscillate at the correct setting, those describe an amplifier that isn't properly tuned to resonance.
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.
Related questions
- G4A01What is the purpose of the notch filter found on many HF transceivers?
- G4A02What is the benefit of using the opposite or “reverse” sideband when receiving CW?
- G4A03How does a noise blanker work?
- G4A05Why is automatic level control (ALC) used with an RF power amplifier?
- G4A06What is the purpose of an antenna tuner?