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Old 2nd Dec 2022, 5:09 am   #318
Radio Wrangler
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Join Date: Mar 2012
Location: Fife, Scotland, UK.
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Default Re: 6-gang FM stereo tuner heads

Spectrum analyser crystal filter design is somewhat contorted to making programmable bandwidths and synchronous tuning shape (not actually Gaussian, though close enough up top)

David Ford's gang did the 3585A over at Loveland, but he'd been at the 'ferry for some time. I think my write-up of the simpler spectrum analyser filter set (in the 3724A) is in the HPJ article (I no longer look like a hairier Harry Potter).

The higher freq analysers use PIN diodes to control stage Q and hence make variable bandwidth.

With so many resistors floating around, loss == noise floor takes a hit.

David
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