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Squeezed or stretched? The tuner output has to be at least as wide as the IF strip. You wouldn't need the IF skirts so much if the tuner were set at 6 MHz wide. Maybe I am misunderstanding your meaning.
Actually, the tuner could be very wide, say 18 MHz. The IF strip just picks out a 6 MHz window as the tuner slides the spectrum back and forth in front of the IF window.
I have seen sets actually tune to adjacent stations when the fine tuning is adjusted far off to the extreme ends of its range. That means that three channels can come through with the channel selector is set to one channel.
This doesn't necessarily mean that the bandpass of the tuner is very wide. But with a good IF, there isn't a need to design tight passbands into tuner mixers and tuner RF amps. I suspect this is the cheapest way to build a tuner and IF strip combination. And it explains why there is rarely a need to re-align a tuner. It is so wide that it doesn't ever go out of spec as part drift out of tolerance. And it explains why the IF strip is so critical. The tuner doesn't do anything to limit the bandwidth. The IF does all the work.
Food for thought.
Steve
I wish you had a pricey spectrum analyzer that could look at the raw tuner output.
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03-11-2014, 09:21 PM
Hybrid Mode
