{Collins} Re: 32S-3 TX Loading question/issue



Glen Zook wrote:
I had a similar problem on my 32S-3 a while back.  It
turned out to be the fact that the meter shunt
resistors had changed value and the meter was
indicating more current than was actually being drawn.

These are a total of 6 resistors, value 12 ohms each,
that go from the cathode connections of the 6146 final
amplifier tubes.  There is a resistor connected to
pins 1, 4, and 6 of each tube.  These form the shunt
resistor for reading the cathode current which is
called "plate" on the meter.

Replace them with new 12 ohm 1% resistors which are
not much larger than the original 1/2 watt resistors
that Collins used.  New resistors are available from
Mouser ( http://www.mouser.com ) for like 16 cents
each in single quantities.  This took care of the
"high" plate current reading on my 32S-3.

By the way, the Heath SB-Line and the HW-10X series
have the same problem except that the resistors in
those units are 10 ohms each.

Glen, K9STH


--- Kc9cdt@xxxxxxx wrote:

1) Same symptoms on all bands
2) When I tune her up all goes well during the initial
tune up in TUNE
3) When I switch to LOCK KEY the plate dips fine, the
exiter peaks fine 4) As long as I keep increasing the
MIC GAIN the drive (plate current) keeps climbing, and
climbing all the way to the right hand peg of the
meter.  The plate still dips fine. I don't let it stay
there long, of course.
5) When I stop with the MIC GAIN at 230ma or so, with
the pate dipped the output into the dummy load is only
60 watts.
6) If I go ahead drive it up more I can get 100 wats
out, but the plate current is pretty high (350-400)
7) The load control does increase loading and output,
but once again if I stop loading at 230 ma (or even
300ma) the output is not up t snuff. Seems like the
drive level is controlling the output as much or more
than the loading.
8) I have tried 2 different sets of finals, the driver
has been replaced.
9) RF alignment went fine, the final and driver
neutralization went fine. Feedback adj went fine.
Nothing funny has happened like oscillation.
10) Tried 2 different 516-F2's









Glen, K9STH

Website:  http://k9sth.com


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Good Morning List,

Glen, I read with interest about the cathode resistors making up the meter shunt in the 32S3 transmitter. The last time I was in my 32S3 I sat there staring at those resistors wondering if I should change them. My unit was manufactured mid 1962 and set dormant for 5-6 years before I got my hands on it. All works well the best I can tell, would you recommend that I have the resistors on hand? And the next time I am in the transmitter, replace them considering their age?

Smith Bradford
W9HAK


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SHARE THE FUN: JOIN THE COLLINS COLLECTORS ASSOCIATION TODAY !
     http://www.collinsradio.org/membership/    -paypal accepted-
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NETS: Tues & Thur: 3.805 MHz-2000 Central + Fri: 3.895 MHz-2000 Pacific
 SUNDAYS: 14.263 MHz-2000 UTC  +  AM Net: 29.050 MHz-1200 Central
      1st Wednesday AM Net 3.880 MHz-2000 local (ET, CT, MT, PT)




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