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Steven,

Receivers provide "selectivity" at various stages - and each have different purposes.

The front-end is selective, and operates at the fundamental operating frequency.? The front-end filtering is generally narrower than the whole band - depending on the type of filtering that's used.? Hamtronics receiver used helical resonators and L/C tuned circuits depending on the model.? Therefore - a receiver generally doesn't pass the entire 220-225 MHz range even if the receiver was built to cover this entire range.? Front-end selectivity is necessary to provide rejection to nearby signals - a few to several MHz away from the operating frequency.? Without front-end filtering - a receiver can be driven into overload easily from other signal sources.

The receiver's first I-F frequency is 10.7 MHz and provides a basic width of the intermediate frequency for two-way radio.? The receivers second I-F is 455 kHz and provides the final selectivity.? These filters determine how well a receiver will tolerate a signal on an adjacent channel that's 15 - 20kHz away or more.? Neither of these filters have anything to do with how wide the front-end is.

My question to you is - what are you wanting to accomplish?? Or, what is the problem that you feel narrowing something is going to help?

Kevin W3KKC