Hi Larry and group,
Please accept my apology for my previous post. I wish I could unsend it.
I should have read your post more carefully and remembered that your
system had been working properly and then developed an intermittant
problem.
Intermittant problems are the toughest to solve. Suspecting one of the
relays being at fault is a good place to start.
Another possibility is that the relays are working fine and there is
something intermittant in the bias control circuitry. I have had parts
on that board get toasty. If you have no load on the output of the
amplifier, and apply drive to it without keying it, the drive power has
no place to go except the parts in the RF sensing circuit on the bias
board. This can fry some of them and mess up the bias switching. Then
after you fix the "no load connected to the amplifer fault", there
another fault to fix inside the amplifier even though you didn't even
have the amplifier on. Sometimes burned resistors can be intermittant.
If the relays switch properly and the bias does not, you will get little
or no RF output.
Check R1 and R11 on the bias board. If they look discolored you may also
need to replace some of the semiconductors around them.
DE N6KB
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