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.


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Richard Knoppow
Los Angeles
WB6KBL

Richard Knoppow wrote:

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.

Did you recap it? S-20R schematics are 'findable' on the web if you
want to revert to the original 'working' version.

-ex

"Bill M" wrote in message
...
Richard Knoppow wrote:
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.

Did you recap it? S-20R schematics are 'findable' on the
web if you want to revert to the original 'working'
version.

-ex

Its been recapped. I have an original insruction book,
actually, it the same one as on BAMA but much clearer, plus
another, a Sam's from another site. I also have the
schematics for all three versions of the S-40. I think the
configuration I have now _is_ the original but it has too
many problems. I wanted to know if this is normal for this
model or not. Its hard to believe its normal. There appears
to be something amis in the detector/AVC but tracing the
wiring has not shown up anything _yet_. I just don't want to
chase my tail if these were just not very good RX to begin
with.
This could also be a wiring error due to the previous
work done. I think I found all of them but maybe not. One
problem is not having a wiring layout. I mean a physical
layout, not just the schematic. They must have existed at
one time but may have all been lost in the sixty-somthing
years since the last S-20R was made.


--

--
Richard Knoppow
Los Angeles
WB6KBL

"Bill M" wrote in message
...
Richard Knoppow wrote:
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.

Did you recap it? S-20R schematics are 'findable' on the
web if you want to revert to the original 'working'
version.

-ex
And please forgive my manners, thank you for responding.


--

--
Richard Knoppow
Los Angeles
WB6KBL