Question T4B08
From subelement T4 - T4B
What is the advantage of having multiple receive bandwidth choices on a multimode transceiver?
Why is this correct?
Multiple bandwidth choices allow you to match the filter width to your operating mode, reducing noise and interference. SSB needs about 2400 Hz, CW only needs 250-500 Hz, and FM requires much wider filtering. Using a narrow filter for CW eliminates adjacent channel interference, while using the proper SSB filter provides optimal signal-to-noise ratio. Choice A is wrong because you select one filter at a time, not multiple simultaneously.
Memory tip
Think 'right tool for the right job' — each mode has an optimal bandwidth sweet spot. Memorize the pattern: narrower modes (CW) need narrow filters to cut noise, wider modes (SSB, FM) need appropriately wider filters. Mismatched filtering either cuts off your signal or lets in unnecessary noise.
Learn more
In practical operation, bandwidth selection directly affects your ability to copy weak stations. When bands are crowded, switching to a narrower filter can pull a weak CW signal out of the noise floor. For SSB DXing, the 2400 Hz filter provides the best compromise between audio fidelity and noise rejection. Understanding emission standards helps you choose appropriate bandwidth for each mode's spectral characteristics.
Think about it
Why do you think using a 5000 Hz filter for CW reception would actually make copying Morse code more difficult, even though it would make the signal sound louder?