Basic Qualification · B-008 Interference and suppression · B-008-003-007
In a Morse code transmission, broad bandwidth RF interference (key clicks) heard at a distance is produced by:
- A sparking at the key contacts
- B mechanical instability in the oscillator
- C poor shaping of the waveform
- D frequency shifting during keying
Correct answer: C — poor shaping of the waveform. From the official ISED question bank, verified word for word.
Why
Broad bandwidth RF interference, known as key clicks, happens when a Morse code signal turns on or off too abruptly, creating sharp edges in the waveform that spread energy across many frequencies. 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.