In a November 1986 HR article, WB3JZO (now KW7CD) explained some easily
accomplished mods affecting noise floor, signal handling, AGC.
While Cornell addressed the Argosy in particular, I found applications for
his ideas in the 544 and Omni C.
It's possible later TenTec rigs might benefit, also.
If you didn't catch the article and can't locate it, I'll be happy to
paraphrase the text and suggest parts sources.
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