CRT tester not so universal

[DavGoodlin]

I almost condemned a perfectly good CRT, a 19CUP4 in a 1964 Philco BW table "Woodstock" model. I usually test a CRT before doing anything else on a set just after I take the back off.

As soon as the heater warmed up, I saw the purple glow in the electron gun and thought I had a gassy tube, even more so when the meter pegged and the current limiter lamps lit full brightness.

I went as far as looking up this kinescope in my 1968 RCA tube manual and could not find it listed there.

Then I pulled out my other tester, the B&K 445 which is NOT recommended to rejuvenate anything, and looked up the CRT on its chart. Guess what?
Its a low-G2 CRT, which I must have rarely encountered before, otherwise this issue would have presented itself long before on the Heathkit tester with another low G2 CRT.