So I got these 1940's tubes in what seemed unused appearance ...I started them off slowly, applied DC heater gently for a few hours, then brought the filaments up to rated voltage (DC) for 6 hours. Then applied B+ and grid voltage at 75% of max dispersion for ~6 hrs.
However, after using the tubes within spec for a week, I've noticed a slight change in appearance - a very slight whitish appearance on some areas of the glass (close to the getter) , where there was crystal clear glass previously.
Should I be worried?
However, after using the tubes within spec for a week, I've noticed a slight change in appearance - a very slight whitish appearance on some areas of the glass (close to the getter) , where there was crystal clear glass previously.
Should I be worried?
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Thanks guys! They are hf200 (PP)
B+ 1455Vdc
G1 - one tube is at -56.9Vdc, the other tube is -57.8Vdc.
The pair drawing 82.3ma
B+ 1455Vdc
G1 - one tube is at -56.9Vdc, the other tube is -57.8Vdc.
The pair drawing 82.3ma
They are running a bit cold according to the design ratings. There are some tubes that have to have a glowing anode to have an effective getter, but cannot say if that is the case here.
With such negative grid voltage the "glowing anode" is unimaginable.
At positive grid voltage and about 300-400mA anode current is feasible.
At positive grid voltage and about 300-400mA anode current is feasible.