Thanks to all who helped with all the good ideas and a special Thanks
to John G3PQA who went the extra mile, exchanged many ideas and Posted
me a copy of a very helpful article.
I got the R4-C fixed and it sounds like first class. John's help (W3RJ
March 1980 CQ magazine article) and questions motivated me to get at it
and try the ideas in the article. The AGC switch was highly modified by
Sherwood and I have no documentation. This made it tough as wires and
orientation did not match up with my old diagram . I ended up with a 2.7
Meg ohms bridged across R-50 and a 2 MFD capacitor bridged across the
.47 mfd C-73 that is in my version. Temporarily sounded great.. But
woe when I put the radio together it sounded bad and the S meter
reading almost zero. The shield near the AGC board goes across
the V5 tube socket. This is supposed to be a 6BA6 and seemed to be
tender. I pulled the tube and it was a military rugged replacement with
very dirty pins I replaced it with a new 6BA6 and it sounded great
again I looked at the pins of the tube socket closely and noticed the
bias pot of the board was actually touching the shield near the tube.
The pot had bent legs. Slight movement of the pot made the problem to be
self evident. Straightened the pot and the radio runs the best that I
have ever heard. Very stable, sweet clean CW note, no clicks or bumps.
(In its normal resting state the bias pot is close to the shield) (
Intermittents and Murphy's laws go together)
Hope this info will help other 160 meter R4-C users.
73
Bruce-K1FZ
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