21AXP22 Vs 21FJP22

[old_tv_nut]

There's another little story about the change to brighter red and yellower green phosphors. If a tube in an old set was replaced with one with more efficient red, the luminance drive to the red cathode had to be reduced so that the correct white color would be maintained, and RCA published a service bulletin showing how to do it.

But wait, you say, the R-Y drive goes to the grid, so doesn't it have to be reduced also?
Well, no. The new CRT with more efficient red also had the yellower green phosphor. Now, turning on yellowish green was like adding a little red at the same time, so you would want to turn off red to a greater extent than before, as the color moved from red to orange to yellow to green. This meant the R-Y gain should increase compared to the Y (luminance) drive, or in this case, R-Y drive (grid) should stay the same when red Y (cathode) drive was decreased. The increased R-Y gain compared to Y had the unfortunate side effect of making pure reds overly bright, but this was preferable to having the wrong hues in between red and green, which included flesh tones.

[Rocket]

Originally Posted by Electronic M

It's hard to pick one favorite! There were a LOT of good performing chassis through the years that each had strong points and weak points.

My TM21 roundy broadcast monitor could probably beat all comers (If I can just get the darn horizontal stable for more than 5 min at a time), but it has unfair advantages of baseband video and being over-engineered to standards that make my 21CT55 seem like a GE portacolor (62 tubes just for monitoring color video where the 21CT55 also tunes broadcasts, has sound circuits and makes due with 37 )...

Someday I when I have my own house I gotta get all my TVs on one floor so I can side by side compare stuff that is split between bedrooms and basement.

62 tubes! wow that's amazing! and with no tuner or audio circuits : D I think my set has only 27 tubes and I thought that was quite a lot of tubes and that's even 10 less than your 21CT55

[Tom9589]

Does anyone have a schematic for the TM-21 monitor that could be posted on the Early Television Museum web site? I would love to see what all those 62 tubes are doing!

[Electronic M]

Originally Posted by Tom9589

Does anyone have a schematic for the TM-21 monitor that could be posted on the Early Television Museum web site? I would love to see what all those 62 tubes are doing!

BenMan posted one here on VK around a year ago. IIRC it got posted to the ETFs site too.

[Yamamaya42]

Originally Posted by Tom9589

Does anyone have a schematic for the TM-21 monitor that could be posted on the Early Television Museum web site? I would love to see what all those 62 tubes are doing!

It also doubles as a heater for small homes.

[Electronic M]

Originally Posted by Yamamaya42

It also doubles as a heater for small homes.

One can do the same with a couple of CTC15s...I sure have.
It occurs to me that one piece of program material I'm sorely lacking is yule log footage for space heater mode.

[WISCOJIM]

Originally Posted by Electronic M

BenMan posted one here on VK around a year ago. IIRC it got posted to the ETFs site too.

Yes, here it is: http://www.earlytelevision.org/pdf/rca_tm21_manual.pdf

.

[kvflyer]

Originally Posted by WISCOJIM

Yes, here it is: http://www.earlytelevision.org/pdf/rca_tm21_manual.pdf

.

213 pounds! What a beast. No doubt, cabinet made of steel.

[Tom9589]

Wiscojim, thanks for the link. That's some set of circuits. Parallel tubes where only one is used in commercial TVs. Delay circuits like the DuMont Sovereign. Regulated power supplies that rival Tektronix 'scopes.

I can only imagine the quality of the picture on this monitor. Are there any screen shots in this forum?

Kvflyer, I have a Sony 36" TV that weighs 182 pounds. And there is very little metal in this TV.

I once saw the two 56" Sony monitors in the Coca-Cola headquarters in Atlanta. They said that they weighed somewhere near 1500 pounds - took a fork lift to bring them in and install them.

[etype2]

[Tom9589]

That looks like an RCA monitor with a 15GP22.

[kvflyer]

Originally Posted by Tom9589

...

Kvflyer, I have a Sony 36" TV that weighs 182 pounds. And there is very little metal in this TV.

I once saw the two 56" Sony monitors in the Coca-Cola headquarters in Atlanta. They said that they weighed somewhere near 1500 pounds - took a fork lift to bring them in and install them.

Tom, that is heavy. Yesterday, I picked up my RCA 630TS (10", B/W set) off of the floor... and I thought that it's 85 pounds was heavy!

[oldtvman]

Even on this forum I see pix of restored color sets where the person who restored it had both the contrast and brightness cranked. In the early days doing that pretty much washed out all the colors and inaccuracy was the result.

Until rare earth phosphors were used even the early and mid-60's sets were prone to the same problem. They always taught us to set up a good black and white image and then add the color. Black levels were key. So I've seen some excellent results from both tubes, but there again it's all a matter of set up and alignment.

[zastin17]

The 21CYP22 looks nothing like a 21FBP. Not even close.
The phosphors are entirely different and are worlds better. It's akin to a 21axp far more than a 21FBP22.

Green phosphor is emerald green, red is like blood or a ruby, and the blue is a deep sky blue.

While the 22FBP22 on the other hand. Green is dark and "minty" and lacks a lot of range.
Red is orange in color and very poppy and "neon" making purples pop really agressiyla Nand faces a bit orange.

So no. The 21CYP22 is nothing lile the 21FBP and the phosphors look nothing alike

In my opinion the CYP22 is the gold standard from this time. It took the very best from the 21AXP and made a reliable glass tube. I have no idea why they got rid of these older early phosphors, but the color gamet is incredibly accurate and close fo real life compared to a 21FPB22. I have all three tubes here one from 1960, the other from 1965 and 1957. Virgin low hour ctc10, and Zenith 27KC20, and RCA Ctc5

I also have a CTC5 21AXP. The CYP is better than 21axp. Improved but the same basic formulation otherwise that can produce that amazing mustard yellow and accurate colors. Faces look correct and very lifelike. The color range and tone is just worlds better and the colors march my modern flatscreen Television. While the 21FBP sort of vears off into it's own.

The easiest way to tell is the vare face of the tube. The older phosphors are very ligjr grey almost white. While the later phosphors are olive in color. No this is not the glass in many cases. I do mean the bare CRT.

21FB22 is the worst for color I have seen in all roundies. I have not seen a 21FJP but I cant imagine its much better.

[zastin17]

I need to add. I do love the 21FBP. It's still a great tube. It's definitely brighter than a 21CYP and definitely a 21AXP. But it has a very special look that makes many films look great. But for some scenes, especially anything with green or yellow/orange. Things can be a tad washed out. But anything with red in it, will practically "pop off the screen" lol