> Both tubes light...I have an "old" set of 572B's that also
> exhibit the same symptom but they were old and I was getting
> suspect of how much life they had left which is why I replaced
> them. They went out of service working fine,
> though. I'll check the tubes with an ohmmeter to be sure.
What brand of tubes do you have? Some brands (Svetlana) required
much higher cut-off bias and were unreliable in certain amplifiers
unless the bias circuit was modified to provide a higher voltage.
You might check your bias circuit to make certain the tubes are
properly cut-off unless the amplifier is in transmit and connected
to proper input/output loads.
73,
... Joe, K4IK
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