This one has me stumped. I received the amp from a
friend that said it got water into it that wicked
down the rotator control cable. Upon inspection,
I found the following problems with the screen regulator
circuit. The 47 ohm resistor in the tube compartment
open, all the Zeners in the regulator string shorted,
the pass transistor shorted and the 15 ohm resistor
ahead of the pass transistor open.
I replaced all the parts, checked the regulator circuit
on the bench, put 400 vdc on the amp screen circuit and
all seemed well. I reassembled everything and, as soon
as I turned the amp on, everything blew again! I took
it all apart, replaced all the defective components again
but this time tried it without the tubes. Everything
seemed OK. I put in a new set of tubes and, you guessed it,
everything blew again!
The screen circuit of this amp is essentially the same as
the Alpha 91B available on BAMA. Any suggestions greatfuly
accepted.
73, Roger N1RJ
--
Remember the USS Liberty (AGTR-5)
http://ussliberty.org/
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