CTC-4 Director 21

[benman94]

The fact that you aren't seeing red doesn't automatically point to the red gun of the CRT. You could (and almost assuredly do) have a matrix or demod issue. My CT-100 had problems in the red adder that completely killed any red on the screen; the 15GP22s strongest gun was actually the red gun however.
If the tube was going gassy, I strongly suspect you'd have at least major focusing issues, etc.
Get the chassis working first, then worry about the CRT. Even if the CRT is garbage, I'd finish the restoration and wait for a clunker CTC-5 with a good 21AXP22 to surface. There's little point in having an operational CTC-4 without a good 21AXP22, and you'd be throwing good money after bad by putting another 21FBP22 or 21FJP22 in it.

[SwizzyMan]

Started to replace some tubes. I also tested the tubes I was replacing and noticed that the 12BH7 R-Y Demod tube has a cathode short. This could explain the absence of red. This short didnt show up on the hickok 600a, but it did show up on the WT-100a. The WT-100 has an extremely sensitive shorts test so I guess it was able to pick it up.

[SwizzyMan]

I've been thinking about stealing the 21ax out of the 5 and putting it in the 4. Does anyone have a glass retrofit kit for the 5? I'm not sure it's a good idea really, but I am looking for authenticity.

[Steve D.]

Originally Posted by SwizzyMan

I've been thinking about stealing the 21ax out of the 5 and putting it in the 4. Does anyone have a glass retrofit kit for the 5? I'm not sure it's a good idea really, but I am looking for authenticity.

My CTC-5 Wingate has the metal to glass RCA Victor retrofit kit to accommodate the 21FBP22 tube that was in it at the time I purchased the set many years ago.
I have never seen another factory kit.

-Steve D.

[DaveWM]

that kinda looks like what holds the CRT in my RCA roundie Test Jig.