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Old 30th May 2022, 10:48 am   #1
Join Date: Jun 2012
Location: Sussex
Posts: 3
Default AM Suppression in SW Receiver

Hi, my apologies if I have posted this in the wrong sub-forum.

I've been building direct conversion short wave receivers from various circuits in books and magazines over the past year or so. Some have worked well and others not so well, but I feel I have learned a lot about RF electronics!

My latest project is for a 20m DC receiver for CW and SSB. It seems fairly straightforward except for the addition of a preset resistor in the tuned RF circuit that is used to 'suppress AM stations' (see picture). I have had AM breakthrough in other designs so this interests me, but I can't work-out how the addition of resistance here achieves this. It clearly adds to the R of the RLC circuit but how would that specifically suppress AM?

Can any kind person please shed some light on how this works if they have seen this before?

Thank you.
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