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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