[AMRadio] Transformer


D. Chester k4kyv at charter.net
Fri Feb 2 20:50:56 EST 2007


The leakage should be very  high, in the tens of megohms.

But if it isn't, don't throw the transformer out just yet.  Let it sit in a 
dry place with low humidity for a few weeks, then check it again.  You may 
be surprised that the leakage resistance has gone much higher.  If it is not 
yet high enough to be satisfactory, let it sit a while longer.

I recall Mike, N14N (now W4AAE), found a 1940's vintage UTC modulation 
transformer that had been stored in an unheated shed since sometime in the 
1940's.  It tested very poorly, with a tremendous amount of leakage.  After 
a few months in his dry shack, the leakage was undetectable with his megger. 
He later used it with a pair of 833A's to modulate another pair of 833A's, 
and it worked just fine.

I suspect that if he had used it in that modulator before letting it dry 
out, it would have failed in short order.

Don k4kyv 




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