Color crt question???

[Pete Deksnis]

It is said that early 21AXP22's have the same 1953NTSC color gamut as a 15GP22, but the later 21AXP22's do not. I do not know the answer, but you may have hit on some real evidence. Can you find a date code on your tube?

[ohohyodafarted]

Hi Pete,

Where would I look for the date codes?

Also the gray phosphor tube is in the newer ctc5 and is coded as a 21axp22a, (I believe it to be the original) where as the olive green crt is in the ctc4 and is coded as a 21axp22. I suspect that the ctc4 has had the original crt replaced at some time, because my first ctc4 that I had back in the 70's had the original factory crt and it had the gray phosphor.

I wish the gray phosphor crt was the good one, because there is a big difference in the way the color looks on a tube with the gray phosphor. the colors seem more vibrant to me. That is what I remember most about my original ctc4 that had the original crt.

Here's hoping that I can find a used gray faced 21axp22 to restore the ctc4 to it's original state.

Even if I could find a dud with the gray phosphor, I would be willing to pay Hawkeye the $700 he wants to do a rebuild on one with the new long heat up and cool down oven cycle, utilizing the oven cams that John Folsum commissioned.

We could use it to test out the new long cycle protocall for rebuilding the 15gp22 crt's

TTYL,
Bob

[stromberg6]

The 21AX in my now working CTC-4 appears to have a slightly greenish tint to the screen. It is a rebuilt without the "A" suffix, and produces excellent color, deep reds, brilliant blues and greens and will converge ok after all other minor cabinet repairs, etc, are done and it is in a more permanent spot. Perhaps it is one of the earlier tubes with a proper color gamut, as Pete notes.
I am trying to reduce the size of my screen shots so I can post a couple on the forum, but so far no luck. I will keep on, though.
Enjoy your 4! I am having a ball watching mine. Let us know how the re-cap goes.
Kevin