Differences in 21FBP22 CRTs

[Tomcomm]

Both my 21FBP22s have no safety glass, so the screen color is due solely to the phosphor. Both are original RCA, not rebuilds. The only numbers I could find were on the pin-caps: the gray screen that's installed has two gray and one green phosphor dots #N JE63619 while the green screen in attic has two green and one bronze phosphor dots #L GA45493. Both are aluminized. Do the cap numbers mean anything? I can slide the yoke over the greeni's broken pin cap so I can repair it with JB Weld then wrap it with thin plastic wrapping tape and try it in the 21CT55. I would still like to know the detailed differences in phosphor between the two.....Tom

[old_tv_nut]

Originally Posted by Tomcomm

Both my 21FBP22s have no safety glass, so the screen color is due solely to the phosphor. Both are original RCA, not rebuilds. The only numbers I could find were on the pin-caps: the gray screen that's installed has two gray and one green phosphor dots #N JE63619 while the green screen in attic has two green and one bronze phosphor dots #L GA45493. Both are aluminized. Do the cap numbers mean anything? I can slide the yoke over the greeni's broken pin cap so I can repair it with JB Weld then wrap it with thin plastic wrapping tape and try it in the 21CT55. I would still like to know the detailed differences in phosphor between the two.....Tom

This would indicate that phosphor formulation was changed without changing the tube type number. The green-green-bronze tube undoubtedly has an all-sulfide screen. Not sure about the other one - can you find date codes on the tubes?

see
http://www.audiokarma.org/forums/sho...d.php?t=105491

[sampson159]

whichever one you dont want,i will take!!!!

[Tomcomm]

I hobbled-up the Green CRT with the CTC2B chassis and checked it out. It's GREEN color bar seemed slightly more vivid then the Gray CRT but the RED color bar seemed slightly less vivid then the Gray. Both produced virtually the same quality pictures. I'll probably run with the Gray and keep the Green as backup. Only numbers were on the pin cap and I assume they were serial #:
Gray- two gray dots and a green #N JE63619
Green-two green dots, and a bronze #L GA45493.
Seems the Gray is a later number? The May,1961 21FBP22 RCA data sheet indicates all Sulfide Type, aluminized. Is there some CRT guru that can decipher the meaning of the SR# and screen # on the Green CRT?