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Old 28th Dec 2022, 4:19 am   #26
Bazz4CQJ
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Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,924
Default Re: Full-Range IF Selectivity; The Hammarlund Variable Crystal Filter

I wanted to simplify the circuit diagram of the filter so I've re-drawn it to British convention and also, I've left out the circuit to switch out the crystal.

Given that the circuit allows a quite wide bandwidth, it seems to me that for a comms Rx, there is no need to switch it out. Leaving out that feature simplifies the construction and will also reduce the capacitance around the crystal. Does that sound sensible?

B
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