Valve testing unexpected high emission?
Hi everyone,
Over the years of restoring vintage wireless sets I have tested many old valves on my AVO VCM.
Every so often one gets a valve that has a great deal more emission than stated in the data.
And occasionally, some valves have an alarmingly high emission and yet still respond to varying the negative grid volts. (so are not just shorted inside)
I am mainly talking about B4 and B5 era valves though have seen this phenomenon in B7G and B9A types too.
My question to the 'experts' is:-
What is actually going on inside these valves that makes them appear to be 'super active' and should one use or 'bin' them?
Thanks in anticipation.
Dave
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