I succeeded in restoring my S-20R to its original
circuit, as far as I can tell anyway. Now, is there anyone
in this group who has an unmodified S-20R that they are sure
is working right that can answer a couple of questions
because I am not sure mine is.
1, Audio volume control leak, i.e., is there still audio
when its turned all the way down?
2, How much distortion is there? Mine has too much and it
gets much worse when the RF gain is turned down.
Both may be due to the configuration of the detector and
AVC circuits but its hard to imagine a radio would stay on
the market very long which was as bad as this.
Its evident that the circuits in the S-40 got revised
soon after it was announced. Since the two circuits are
nearly identical I am about to modify the S-20R to the
revised S-40 circuit, which has a separate diode for AVC
(eliminates the gas gate half of the 6H6) and uses "contact"
bias for the 6SQ7 audio grid.
I've checked my wiring and can't find any errors but,
since the thing was heavily modified when I got it, I have
no idea of the original wiring layout and none seems ever to
have been printed.


--

--
Richard Knoppow
Los Angeles
WB6KBL