Re: AVO CT160.......dancing meter during TEST
You have a stable reading when looking at anode current: when you move to gm reading the sensitivity of the meter increases dramatically.
The drift you observe is common and related to the thermal properties of the valve.
The "noise" may well be the result of running the instrument directly from your mains supply, which may be fluctuating slightly. I don't think there's much wrong with the CT160 itself, but cleaning the contacts won't do any harm. The gm potentiometer is the obvious candidate for cleaning (wiper to track).
John
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