Basic Qualification · B-008 Interference and suppression · B-008-001-007
You have connected your hand-held VHF transceiver to an outside gain antenna. You now hear a mixture of signals together with different modulation on your desired frequency. What is the nature of this interference?
- A Audio stage intermodulation
- B Receiver intermodulation
- C Harmonics from other stations
- D Audio stage overload
Correct answer: B — Receiver intermodulation. From the official ISED question bank, verified word for word.
Why
When strong signals from nearby transmitters enter your receiver, they can mix inside the radio's front end to create new, unwanted frequencies that sound like a jumble of different voices and tones on your desired channel. 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.