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.