[hsusmann]

I know that the 00-A tube contained trace amounts of gas
and it was used as a detector tube and apparently worked
better than an 01-A for that function. I am not sure what
gas was used. There are of course gas filled regulator tubes
but that's a different story.

I have more interesting developments in this saga that turned
up last night:

I got thinking about it more and realized that my tube tester
actually can't test for gas in rectifier tubes. I realized that
I had tested the other triode tubes for gas but not the
80 rectifier. I don't know why I forgot about this yesterday.

Anyway, I re-read the instruction book for my Hickok
600A tester and I think I was wrong in saying that the #80
tested good. Actually I am concluding now that it tests
bad. The confusion comes from what the definition of good
and bad is for big rectifier tubes.

In my notes for the settings for the #80 I had written that
any reading above "diodes and Rect OK" on the meter was good.
After re-reading the manual, I think actually for Rectifier tubes
it has to be in the green zone to be good. Only "Diodes"
are good above the "Diodes OK" line. The printing on the meter
actually says "Diodes OK" not "Diodes and Rect OK".

I think because the needle was above this line I was assuming
it was good because a rectifier is a diode after all but
actually that is wrong. They mean for small signal diodes
like the 6H6 etc... not for rectifier tubes.

I re-checked a #80 that does not show any violet or blue
glow (ST type) and it reads in the green "GOOD" zone.
My suspect tube reads in the RED zone but above the
diodes OK line.

I am wondering if someone out there would know how to
check for gas in a rectifier tube? Maybe the violet glow is
telling me that?

I have applied negative plate voltage to the tube (only about -60v)
and I get 0.00 microamps on a 200 uA scale so I am certainly not
reading any reverse current at least at -60v bias.

Is there some other way to test for gas? Higher negative bias?