The Basic lessons · Interference and suppression · B-008-003

Stopping Unwanted Signals: Intermodulation and Spurious Emissions

Learn why radios sometimes create new, unwanted frequencies and how to stop them. This lesson explains spurious emissions, intermodulation, and key clicks so you can keep your transmissions clean.

This lesson is part of SignalPrep Pro. The subsection's 11 exam questions are free to practise: practise B-008-003.

What this subsection asks

• What term describes the undesired creation of new frequency components when one or more signals enter a non-linear device?
• If someone tells you that signals from your hand-held transceiver are interfering with other signals on a frequency near yours, what could be the cause?
• If your transmitter sends signals outside the band where it is transmitting, what is this called?
• What problem may occur if your transmitter is operated without its cover or other shielding in place?
• In Morse code transmission, local RF interference (key clicks) is produced by:
• Key clicks, heard from a Morse code transmitter at a distant receiver, are the result of:
• In a Morse code transmission, broad bandwidth RF interference (key clicks) heard at a distance is produced by:
• What should you do if you learn your transmitter is producing key clicks?
• What term describes an unwanted oscillation in an amplifier or oscillator circuit?
• What can cause parasitic oscillations in a stage?
• Transmitter RF amplifiers can generate parasitic oscillations: