Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-001-004
Why is the Colpitts oscillator circuit commonly used in a VFO?
- A It can be used with or without crystal
- B The frequency is a linear function with load impedance
- C It has high output power
- D It is stable
Correct answer: D — It is stable. From the official ISED question bank, verified word for word.
Why
The Colpitts oscillator is chosen for a variable frequency oscillator, or VFO, because its design uses two capacitors and one inductor to create a very steady signal that resists drifting when temperature or voltage changes. 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.