[Collins] 32S-3 self oscilation and tuning problems

[Dr. Gerald N. Johnson]

On Thu, 2008-10-23 at 22:22 -0500, Jaime Gomez wrote:
> Hey dear fellows,
> Finally I found the cause of my headaches. First, I want to thank all
> who gave me indications to follow in getting the self oscillation
> solved. I followed all of them, but finally, I found that C 62 - 1000
> pf feed-through was actually 68 pf...., almost shorted out...,
> I replaced it, I could not find the exact one but a 1000 pf
> feedthrough that can withstand the voltage present and I could start
> getting "quite normal" responses from the final stage, I followed
> again and for the 100th time the neutralization procedure
> and ....voila !!!! it is working now....

Aha, it wasn't neutralizing properly though you did the procedure. We
thought it was neutralizing properly. That capacitor has been known to
be a weak part in the 32S-1/2. I didn't know it was in the S-3 also. But
its sure something to check for.
> 
> Well, I am quite happy that I can continue getting my S line on the
> air.
>  
> Now, I have another question: I have a 30L-1 (round emblem) and a
> Rockwell-Collins KWM2A that have the plastic trim ring instead of the
> metal one. Those plastic rims are kind of dirty yellow.I wonder if
> they were originally the light blue I have in all my other Collins
> (with the metal trim rings) or if with time and hot and humid weather
> here they have changed in color.

They were the color of the cabinet. They can be painted as the metal
ones were.

>  My question is, if they have changed, where can I get a good copy of
> the original ones? or if that is the original color, I would like to
> know, because then I won't worry more about it.
>  
> I still have 2 30L-1s to recover and my nice jewel, a 75A1 that has
> been packed for over 16 years (which is same age as me, heheheh).... I
> hope I won't have too much trouble with it..., and I have an R648/ARP
> 41 for which I need to get the PTO gear.....but those will come
> later....

The A-1 will need all the black beauty oil paper capacitors replaced as
well as all the electrolytics and probably some fraction of the tubes
and ceramic trimmers.
>  
> Sorry for the space, 73

No need to be sorry, we all LEARN from diagnoses of troublesome rigs
fixed.
>  
> Jim, HK1N
> 
> 

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer