[Collins] 32S-1 grid problem

[Glen Zook]

The random serial numbers did not really start on the
S-Line until the S-3 series.  Art started the random
serial numbers after the 75A4 receivers started
becoming valued by the serial number.  However, this
did not become apparent until after the S-1 / S-2 line
had been in production for a while.  Therefore, the
serial numbers on the S-1 and S-2 were sequential. 
Remember that the S-1 / S-2 series was not
manufactured that long when compared with the S-3
series. The S-1 / S-2 series was introduced in late
1957 for the "1958 model year".  The S-3 started in,
if I remember correctly, 1961.  The serial numbers on
the KWM-2 series atarted being "randomized" just
before the S-3 series came out if I remember
correctly.  At least that is the "story" that I was
told when I was with Collins Radio.

The problem is not in the tubes.  I have removed them
from the sockets and the problem is still there. 
Also, I replaced all of the paper capacitors (2 "black
beauties" and several "green beauties") with orange
drops since those are the most likely to cause
problems.

I agree that the problem is in the grid circuit. 
However, since the actual circuit is basically
"unknown" since it differs considerably from that in
the manual and it is difficult to trace.

What I was hoping to find was someone that has the
actual schematic since that would make it considerably
easier to trouble shoot.

As far as the neutralization circuitry goes the
earlier versions of the 32S-3 and 32S-3A use basically
the same circuitry as the 32S-1 (ceramic trimmer). 
Remember that the 6146B was not introduced by RCA
until February of 1964 and the military did not change
the 6146W from the 6146A equivalent to the 6146B
equivalent until some time later in 1964 (different
suppliers had their contracts changed at different
times).  It was sometime in late 1964 or early 1965
that the problems with using the 6146B arose and
Collins had to change the neutralization circuitry in
the S-Line and KWM-2 series to the air variable and
make a field kit to modify those units already in the
field.

If you are not fully familar with the 6146 family of
tubes I suggest that you go to either website that is
listed at the end of this message where you will find
the article on the 6146 family of tubes that was in
Electric Radio a while back.  It also has been
reprinted (with my permission) in several other
publications concerning amateur radio over the past
several years.

Glen, K9STH


--- Gerald <geraldj at ispwest.com> wrote:

>Sounds like there is a leakage or short to ground on
the grid side of the meter.
 
There is a black beauty C142 in the ALC circuit that
will leak and cause that symptom.
 
Serial number means NOTHING about age. They were
issued in random order.

Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco


		
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