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stainless · 21st Mar 2018, 10:59 pm

I remember my Armstrong 626 - the AM sounded very muffled - indeed the audio frequency response began to roll off at 1kHz. I took it back for re-alignment - no change. There is nothing anywhere in the spec about the AM frequency response.

I also found that the 20volt stabiliser for the varicap tuning voltage drifted (temperature ??) and replaced it with an SN76552 (the 22volt version of the usual 33volt stabiliser in TV varicap circuits) cured that problem

21st Mar 2018, 10:59 pm	#10
stainless Tetrode Join Date: Jun 2006 Location: London, UK. Posts: 70	Re: Armstrong 625 receiver I remember my Armstrong 626 - the AM sounded very muffled - indeed the audio frequency response began to roll off at 1kHz. I took it back for re-alignment - no change. There is nothing anywhere in the spec about the AM frequency response. I also found that the 20volt stabiliser for the varicap tuning voltage drifted (temperature ??) and replaced it with an SN76552 (the 22volt version of the usual 33volt stabiliser in TV varicap circuits) cured that problem