Basic Qualification · B-008 Interference and suppression · B-008-004-005
If you are told your station was heard on 21.375 MHz but at the time you were operating on 7.125 MHz. What is one reason that could cause this to happen?
- A Your transmitter's power-supply filter choke is defective
- B You were sending CW too fast
- C Your transmitter's power-supply filter capacitor is defective
- D Your transmitter radiates harmonic signals
Correct answer: D — Your transmitter radiates harmonic signals. From the official ISED question bank, verified word for word.
Why
Your transmitter radiates harmonic signals, which are unwanted copies of your main signal at exact multiples of the original frequency. The full explanation — and one for every question — is in Pro.
Practise this section
When things interfere: harmonics, overload, RFI to and from your station, filters, ferrites and how to fix the neighbour's TV.