Basic Qualification · B-008 Interference and suppression · B-008-003-005
In Morse code transmission, local RF interference (key clicks) is produced by:
- A poor wave-shaping caused by a defective filter capacitor
- B the making and breaking of the circuit the Morse key
- C frequency shifting caused by poor voltage regulation
- D high frequency parasitic oscillations
Correct answer: B — the making and breaking of the circuit the Morse key. From the official ISED question bank, verified word for word.
Why
When you press or release a Morse key, you instantly connect or disconnect the radio's power circuit. 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.