[AMRadio] R-388 PTO info needed


Darrell, WA5VGO hbrnut at earthlink.net
Sun Dec 25 21:05:13 EST 2005


I had the same problem several years ago. I found an open resistor in the 
PTO. Check the voltages on the two PTO tubes. You'll find the problem.

73,
Darrell, WA5VGO




At 04:47 PM 12/25/2005 -0500, you wrote:


>   Further to my Xmas Eve Scrooge Radio Post - I have discovered that no 
> signals of any kind appear on the PTO output cable when isolated from the 
> mixer tube, and injecting the correct frequency into that pin of the 
> mixer (from my bench oscillator) restores the radio to operation.
>
>  So, of course, the PTO has quit, and the tubes (AFAIK) are good - but 
> next I'll replace them with a couple that test out at better than 70% Gm 
> - somehow I think that's not going to be the Problem.
>
>
>   If anyone within the sound of my keyboard has any experience actually 
> repairing this series of PTO - it's a Collins 70E-15 ser. M1751 - I'm 
> trying to guage whether I should spend the time to dredge it out and fix 
> it - or (since the front panel needs to be refinished) I would be better 
> served by just bundling it off to someone and letting an expert refurb 
> the radio. I do plan to keep it, it's my Fave Reciever - for Ham and SWL -
>
>  Also: if you have a quote to perform the above, lemme know ASAP - I'm 
> 'motivated' as they say in Real Estate.
>
>  Cheers and Best of the Season!
>
>
>John  KB6SCO
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