Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-003-010
Why is neutralization necessary for some vacuum-tube amplifiers?
- A To cancel AC hum from the filament transformer
- B To reduce the limits of loaded Q
- C To cancel oscillation caused by the effects of interelectrode capacitance
- D To reduce grid-to-cathode leakage
Correct answer: C — To cancel oscillation caused by the effects of interelectrode capacitance. From the official ISED question bank, verified word for word.
Why
In vacuum-tube amplifiers, tiny internal capacitances between electrodes can accidentally feed a portion of the output signal back to the input. The full explanation — and one for every question — is in Pro.
Practise this section
Transmitters, modulation and processing: AM, FM, SSB, keying, speech processing, and the numbers behind occupied bandwidth.