Greetings,
I had an odd thing happen with my AL811H (four 811As - Grounded Grid) this
afternoon. When I turned on the main power switch I heard a loud pop and
saw a flash. After that the amp had normal high voltage but would only
produce low power with higher VSWR. After taking it apart, I discovered
that three of the resistors that run from the grid to ground had "blown"
apart. I can easily replace the resistors, but would like to know what
caused it. I can find any other burned parts and everything seems "normal"
(except the low power). I noted that two of the tubes (Svetlana 811As) have
slightly deformed plates--but a quick check with a VOM does not show a
short.
Any ideas on what might have caused this?
73 de Tom, K4NR
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