Question T7B07
From subelement T7 - T7B
Which of the following can reduce overload of a VHF transceiver by a nearby commercial FM station?
Why is this correct?
A band-reject filter is correct because it specifically blocks the interfering commercial FM frequencies while allowing desired VHF signals to pass through. RF preamplifiers would amplify both wanted and unwanted signals, making overload worse. Double-shielded coax and bypass capacitors don't address the fundamental issue of strong RF signals overwhelming the receiver's front end.
Memory tip
Look for filter solutions when dealing with frequency-specific interference problems. Band-reject filters target the exact frequency range causing trouble, while amplifiers typically worsen overload situations by boosting all signals indiscriminately.
Learn more
Overload occurs when strong signals outside your operating frequency saturate the receiver's front-end circuitry, causing desensitization or spurious responses. Commercial FM stations operate at 88-108 MHz with significant power, often creating interference to nearby VHF amateur operations. A properly designed band-reject filter attenuates these specific frequencies while preserving receiver sensitivity on desired amateur frequencies, maintaining emission standards compliance.
Think about it
Why do you think an RF preamplifier would actually make the overload problem worse rather than better?