A CRT went to air

[Eric H]

Well this sucks, 3 or 4 years ago I bought a wreck of a 1950 GE 12", turned out it had a 12KP4 that tested good.
I parted the set out and stuck the CRT in my storage room where it's been sitting for the last couple years, I've been cleaning up around here and decided to give the tube a bath since it was filthy dirty, before I did I wanted to retest it and make a note of how well it tested.

As it turned out when I hooked it up the first thing I noticed was the heater seemed dim, I also couldn't get the Cutoff to adjust, I knew this tube had checked OK so I bumped the voltage up a bit to 8 volts, the heater got brighter but still no cutoff or emissions, then I noticed the Getter, it basically wasn't there, just a slightly cloudy film where it should be, also the heater kept getting dimmer and finally quit so I knew for sure what had happened then.

I pulled of the base cap, it was loose to start with and I thought maybe the evacuation nipple had been broken somehow but it was in perfect shape, in fact I found no definite cause of the problem except some suspicious looking areas where the wires go through the base.
Finally I snipped of the nipple to see if any vacuum was left, there was still quite a bit but not enough for it to work or even keep the heaters from burning out, I guess it just decided to leak after being disturbed when I took it out of the set, 63 years old I guess anything can happen.

So it wouldn't be a total loss I decided to see if I could fix the loose base on the 12" Philco I just bought, that base came off really easy since there was really only one or two wires still soldered to it, fortunately all the wires from the CRT are intact, however there's so much of the glue still wrapped around them I decided it would be a disaster to try and remove it.

It was easy enough to get the wires threaded through the new base but when I tried to push it over the glue it was a bit too tight and it broke the base in several places, luckily it didn't hurt the CRT, but now I need another base cap to try again and I don't have any tubes dead enough that I would want to junk them for a base.

This picture is of the good Philco tube, I think it best to leave the glue alone and just add some glue to the new cap, after I grind it out a little so it will fit easily over it.