RCA roundie test jig

[DaveWM]

I have not looked closely enough to see if the 'test tube' is there.

I wonder if that could be ground out (that is if I wanted to use the tube in a tv set).

hmmm since it clearly has a bonded tube in there I wonder if it were etched, would it be on the bonded lens and not the CRT face?

[marty59]

Seems kinda' strange that it has a 21FJ in it..I wonder if that is a used tube replacement from another set?
I can't say that I've seen one of those before...interesting piece!