[Don Moore]

The tube has a 4-pin base. Unfortunately I haven't been able to find any
information on it. Is it similar to a 10? I came across UX210 and 210T,
but I don't know if they are at all similar to this. The printing is in
script upwards to the right, and then a bold "210" under that and straight
across. It looks a bit artistic. 1920's? I don't know how to describe the
envelope - it tapers up from the base to about 1-1/2" diameter, and then
1/2" up the side, tapers out to 1-3/4". Then straight up about 4" and a
hemispherical top. The tube is about 5" tall.

If anyone can help me out, it would be greatly appreciated. I would like to
test it on my 600A tester.

Thanks in advance. Don

[Don Moore]

Thanks a lot! I am obviously a novice, and a half hour of distracted
searching (got stuck in some tube museums) yielded an insufficient amount of
information.

I really appreciate this. Thanks, Don