[Collins] 32S-3 problem

[Dr. Gerald N. Johnson]

I've seen that problem before. With the 42K, the relay tube isn't quite 
cutoff as well as if there was 34K. You could put 150K 1 watt in 
parallel with the 32K and be much closer. Without the 150K the relay 
tube will run a little hotter and the VOX sensitivity will be greater.

Mouser doesn't charge a fee for small orders, just shipping will hurt 
the msall order a lot. They can ship at least half a pound for the same 
roughly $6 postage.

Relay contacts are suspects in lack of drive, not applying power to the 
right stages. Also oscillators, and every tube and transformer from the 
audio input to the PA grids. The only way to find the problem is by 
checking AF and RF voltages from beginning to end. Its handy to do a 
binary chop, start at the middle and move forward or back according to 
what's found, then split that half in half and repeat until the stage is 
isolated.

Make sure the crystal and PTO jumpers are in place, not been left out to 
use the receiver crystal and PTO signals as in transceiver service. This 
is a very likely problem and easiest to cause and to fix, but nearly 
every part in the transmitter contributes to the PA grid drive so they 
are all suspect at age 45 or 50.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.

On 12/12/2014 4:26 PM, Al Parker wrote:
> Thanks again to Jerry and Alan,
> That was the problem. I subbed about a 42k ohm 5 watter temporarily, and
> it's OK. Now on to figure out why no RF is getting to the finals.
> I've been procrastinating a long while on getting an order off to
> Mouser, now I've got a good reason, plus I can get enough to do some
> preventive maint. on my own 32S-3 (if it hasn't already been fixed).
> tnx agn,
> 73,
> Al, W8UT
>
> On 12/12/2014 12:28 PM, Dr. Gerald N. Johnson wrote:
>> Mouser has 68K 3 watt and 5 watt metal film and wire wound that will fit.
>> www.mouser.com/Passive-Components/Resistors/_/N-5g9n?P=1z0wszxZ1z0wui7&Keyword=68k+3+watt&FS=True
>>
>>
>>
>> Mouser also has 33K 5 watt metal film and wire wound that will be
>> slightly more compact, but less original, though like the 32S-3A.
>> www.mouser.com/Passive-Components/Resistors/_/N-5g9n?P=1z0wszxZ1z0wui7&Keyword=33k+3+watt&FS=True
>>
>>
>>
>> Metal film or wire wound and with a greater power rating will solve that
>> relay tube problem virtually permanently. The originals are bound to
>> fail, faster with modern line voltage raising the low B+ voltage. Those
>> two carbon composition resistors were not the best choice for that
>> circuit.
>>
>> 73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association
>>
>>
>> On 12/12/2014 11:00 AM, Al Parker wrote:
>>> Thanks, Jerry,
>>> Thanks for the detailed explanation. I've found something I can put in
>>> for a test, but will hold out for something more durable for a permanent
>>> fix.
>>> 73,
>>> Al, W8UT
>
>