Color crt question???

[julianburke]

In the 60's when we were replacing the round tubes, I always preferred the sulphide (green tube) screen as I always thought they had a richer color to them-much like a Technicolor picture. I remember doing a CTC5 with a sulphide FB and what a picture! There was also a difference in price between the two as the gray screen "rare earth" was about $30 more. In the early 70's I remember the dud allowance being removed on the sulphide as we didn't require a dud on those-just the rare earth. We also sold a lot of Zenith tubes and they didn't require a dud on the roundies so we had a lot of those duds on hand. I wish I had them now!

[sampson159]

i like the green too.just has a more pleasing to the eye look. the gray is good,i ll take the green!!

[vintagecollect]

looking at this old thread.

The ctc4 and ctc5 BOTH grey 21AXP22 CRTS while not seeing a ct-100 in person these sets benefit being in subdued light since contrast declines in brighter lighted room. There's a subway commercial I compare my modern tvs green to my roundie sets green. The lettuce is bright green on old and new sets, the green seems lighter on older sets.

In general grass seems light, reds are eye popping, blues slighty subdued is my take from general watching without use of special equipment.


Grey crts seem to have a critical bightness level to them where contrast is good yet screen doesn't appear too dark. The brightnees can be adjusted high where dark areas of screen appear lightened. These CRTS are fun to have but a newer fjp or fbp tube have more contrast. Older CRTS have less contrast in moderate to bright sunlight. These older sets interpret color changes with stations, program material and quality. The NTSC signal from old sets is shown without newer advanced compensating or color balancing circuits, wouldn't these make great station color monitors?


While the novelty of orginal CRT is great why isn't newer tubes considered an upgrade?? The 65' zenith I had was more watchable in daylight and appeared to have greater contrast. brightness seemed less critical to screen quality also. Overall seems upgraded set is more watchable. Using special color meters or other equipment seems overdoing it to prove older tubes have better color .Usually better performance meansan upgrade.


I guess if a newer 15" version of color tube with greater contrast and brightness were available, people would still be chasing those old original tubes.

I watched my set for 6 hours today. The daylight conditions seem to effect grey CRTS pretty much the way room or sunlight has effect on a video projector screen. Light bouncing off crt face and back to viewer. The green screen crts I don't think really aren't that very much brighter you just dont have light bouncing from the room back at you as much. this post updated sice my grey crt had plenty of bightness today which worked actually really well with window opposite of set! but the contrast declined at least some in brighter light conditions. Projector people use the phrase "contrast ratio" older crts must their contrast ratio declined in competing light . My 1996 mitsubishi is much newer and has a black face crt still suffers reflections from the crt glass itself.

[old_tv_nut]

I recently came across this patent for an all-sulfide screen.

[Pete Deksnis]

Originally Posted by old_tv_nut

I recently came across this patent for an all-sulfide screen.

Interesting that in 1959 -- the date of the application -- the CIE color coordinates for green were still the 1953 NTSC values. Although the author adds the caveat 'most' when referring to color CRTs available then, he does specify both the 21AXP22 and the 21CYP22 as meeting the original NTSC green standard. There is documentation that indicates the 21AXP22 does, but this is the first time I have seen something including the 21CYP22 as well. I suspect the 21CYP22A however does not, as this was touted as a 'brighter' tricolor tube but with greater lag, IIRC.

[old_tv_nut]

I found a reference to the color of the sulfide red and vanadate rare-earth red. "The Performance of Color Television Picture Tube Phosphor Screens", Austin E. Hardy, RCA, in IEEE Transactions on Broadcast and Television Receivers, Vol 11, Issue 2, July 1965. Hardy says that the vanadate rare earth red had a constant color practically identical to the NTSC standard. The sulfide red, however, was the same as the vanadate at low current, but shifted toward orange at high current. Both of these red phosphors were used with sulfide green and sulfide blue (which are non-NTSC). I have attached some plots showing NTSC, the vanadate red, and the color shift of the sulfide red for comparison. This shift would be rated "large" on a general color-difference scale, about the same as the change from NTSC green to the yellower sulfide green.

[old_tv_nut]

Here's a 1964 ad from Sylvania touting rare earth red phosphor. Note the side-ways reference to the variable color of the sulfide red.

[julianburke]

I always liked the pea green face as it was a true sulphide screen and always liked their color as it was more colorful to me and looked very much like "Technicolor". They had a georgeous red.