Isn't the most up-to-date round tube the 21GVP22? (there is also one designated as 19V...something, from when the viewable image area began to be used in the designation). My RCA service manual lists all of the different round types, with their properties and necessary changes to make for upgrades, through the 21GVP22. It is listed as having a rare-earth red phosphor with unity current ratios. I had one in a set I just bought, but it was arcing, so could not determine how it looked (this 21GVP22 was a replacement made in 1969). The date code is listed on the label for the tubes I have.

Re: Dates
 

I think you are right about the date codes. The date code on my RCA CRT in the Curtis Mathes reads 66-35, which would mean 35th week of 1966... and this would coincide the rest of dates stamped inside the set.

Hey Eric, good catch, my tube is marked 66-09, which means my tube was probably installed sometime later on in 1966.

wasnt the 19vabp22 the last roundie tube upgrade?
thought i remembered installing a few.
they even had the black matrix treatment iirc

Just in time to watch "Batman" no doubt :D

The colors on that show are still eye popping!

19VABP22 is listed as a rectangular. Perhaps you were thinking of a similar number? The only roundies I can find listed with a number starting with 19 are the 19VP22 (CBS) and 19TP22 (DuMont) both from 1954.

Chad,

I found listings for 21GUP22 and 21GVP22. They are electrically identical with each other. Both have rare-earth red phosphors. The only difference appears to be that the 21GVP22 has an anti-reflective faceplate (laminated?) These types are similar to the 21FJP22-A except they have higher G1 and G2 voltages listed.

Aren't these types Zenith tubes? IIrc, Zenith made their own tubes and used numbers different from RCA's in their round tube sets. I do not remember RCA supplying tubes with these type numbers.

Using multiple sources these are all of the round tubes I can find listings for:

15GP22 /RCA /1954 /flat plate screen
19TP22 /DuMont /1954 /curved faceplate screen
19VP22 /CBS /1954 /curved faceplate screen
21AXP22 /RCA /1954 /metal cone, curved faceplate
21AXP22-A /RCA /1956 /multiple improvements
21CYP22 /RCA /1957 /all glass, improved brightness
21CYP22-A /RCA /1959 /(?)
21FBP22 /RCA /1961 /equalized beam currents, improved brightness
21FJP22 /RCA /1961 /same with anti-reflection faceplate
21FBP22-A /RCA /1964 /rare-earth red phosphor
21FJP22-A /RCA /1964 /rare-earth red phosphor
21GUP22 / (?) /(196?) /r-e red phosphor
21GVP22 / (?) /(196?) /r-e red phosphor, a-r faceplate

The 21GVP22 I have is branded RCA with a date code of 1969---perhaps could it be actually made by Zenith but labled RCA?
Also I'm sure there is a 19V-type 21 inch round tube made in the late 60's or in the 70's. It is listed in the 1974 GE tube manual. I'll have to double check the number later today.

...

Andy,

You are correct. I overlooked the 21FKP22 and 21GYP22 in my search. They are also listed in the GE tube manual. I can find no information about which manufacturer introduced these types, or what year.

Also, the CBS 15HP22 and 19 inch Colorton 205.

21CYP22
 

This is the original 21CYP22 jug in my 1959 CTC9N, remote model.
Great discussion! I am a former RCA Service Co. Tech. I now teach Major Appliance Repair. Those are great backround shots!

21CYP22
 

Hmmm . . . . the red certainly does look red in this shot. Is your tube the "A" version?

21cyp22A
 

i am confused about what tubes produce a proper red,i had read someplace last year that the 21fb22 was the one with a more reddish orange phospher,i had a ctc-9 that had a 21cyp22A and i looked at the red closly and thought that it had perfect red,while doing purity,i looked at my ctc-7 with a 21fp22 and of course it is perfect red also. (but much brighter than the 21cyp22) .and no i am not color blind!!
i have been searching for a 21cyp22 to install in my ctc-7 to make it original,but if the 21cyp22 version is really the one with poor red then i will just keep the 21fb22 installed..
terry

Terry,

I once had a CTC7 with a 21CYP22, and the reds looked orange. I have also seen that orange-looking red on some later Zenith sets, including some with rectangular tubes.

The 21CYP22 was the first RCA tube that deviated from the NTSC-correct color phosphors. One thing that was done was to shift the color temperature of the mix more toward blue, which appears brighter to the eye. A new red phosphor was used also, supposedly the one that looked orange. I'm wondering if they changed that phosphor again in later versions, to one that looked red. Another thing was to make the holes in the mask larger near the center of the screen, making the center brighter, which tricks the eye so that the entire screen appears brighter.

No matter what type of phosphors are used in a color picture tube, they are all given the same EIA registration number "P22", regardless of material, color temperature or efficiency, making it impossible to determine what is in a particular tube. If you want a 21CYP22 for your set, I would suggest viewing a picture on it first. If you are satisfied with how it looks, then buy it.