Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-003-008
Parasitic oscillations are usually generated due to:
- A a mismatch between power amplifier and transmission line
- B accidental resonant frequencies in the power amplifier
- C harmonics from some earlier multiplier stage
- D excessive drive or excitation to the power amplifier
Correct answer: B — accidental resonant frequencies in the power amplifier. From the official ISED question bank, verified word for word.
Why
Parasitic oscillations happen when a power amplifier unintentionally creates its own radio signal at a frequency it was not designed to handle, usually because stray capacitance and inductance inside the circuit form an accidental resonant circuit. 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.