CTC-2B serial B8801632 followed me home from the convention in Hilliard. :thmbsp:

Congratulations mate!!!! :D

Wow!!http://www.youtube.com/watch?v=2S60N2W5xzkWe'll see all our color shows now!
Congratulations!!

Ah HATE Yew !! -Yosemite Sam, Esq. (grin)

Nice!!!

And now, the obligatory chassis 'nudes'. :D

The top looks dirty, but it wipes down to perfectly clean metal underneath. No corrosion whatsoever. Under the hood, some recapping has already been done by the PO. I will still replace the cheap 'lytics with higher quality Nichicons or Panasonics just to be safe, then replace what is left of the originals if they are bad. Some parts of the underside are still clean enough to eat off of.

That is a really clan chassis. Should make for a great restoration. A thanks to yoda, too! Beware those white peaking coils, some or all may be open.

Yes, 3 cheers to Bob for giving it (and me!) a lift back to Chicago!

I already know about the coils, but I have a plan. It looks like the metal leads is what corrodes, leading up to the thin wires of the coil causing it to open up. I think if I clean the leads and resolder the wires, it might work. Then I would recoat them in wax or something. Failing that, I can always replace them.

Welcome to the 21CT55 / CTC2B club. Appears this chassis is almost completely recap'd. Amazing most original RCA "plaster-coated" chokes are still in there, I replaced almost all of mine. Who did you buy it from? I wont ask for how much, but feel free to volunteer a cost. Lotsa luck re-activating it...Tom

I don't remember the name of the man I bought it from, this was my first convention. I'm sure someone else does, though. I'd rather not say how much I paid, but suffice it to say the Museum made quite a bit during the auction. I recall Steve said they take 10%.

doesnt matter what you paid.that set is worth a bundle!beautiful piece to own at any cost.it must feel good to be you right now

doesnt matter what you paid.that set is worth a bundle!beautiful piece to own at any cost.it must feel good to be you right now

Yep. 25 years from now, you could STILL have it, & it will still likely be working, assuming nothing untoward happens to it, & about ALL the folks who have laid out megabux at the local electronics big-boxmart for a super hi-tech high-chromo-promo-domo-gizmo HDTV w/all the bells 'n' whistles are likely gonna have just vague memories of it...

Agreed.

I will say that it wasn't as much as a working CT-100 might go for, but I get the impression that at any other convention I would have been bidding against more than one person. That probably had more to do with it than anything else, if there had been more interested parties I think the set would have gone for a lot more than I paid- especially when taking it's condition into account. The chassis and cabinet are very clean, flyback looks good, the CRT is a 1954 one and pegs the tester on all 3 guns even with 5 volts on the heaters. All in all I'm very pleased with the purchase, and look forward to getting it operational.

Last night I pulled the front glass off and cleaned the CRT. It looks a lot different than other 21AXP22 tubes, the phosphor has a different color to it.

This set is from the estate of Danny Gustafson. Ed Alfonsi brought this set along with the Dumont 183, CBS 205 and Zenith SKF to the convention. This set along with a Model 5 are about the only two sets I can think of that Danny had kept in working order as he like to actually use these. While it was in working order up until Danny's passing in 2002, I doubt it has been operated since then.

Darryl

If the Zenith CBS system set was auctioned, can anyone tell us what the final accepted bid was? I for one am darn curious!

Agreed.

I will say that it wasn't as much as a working CT-100 might go for, but I get the impression that at any other convention I would have been bidding against more than one person. That probably had more to do with it than anything else, if there had been more interested parties I think the set would have gone for a lot more than I paid- especially when taking it's condition into account. The chassis and cabinet are very clean, flyback looks good, the CRT is a 1954 one and pegs the tester on all 3 guns even with 5 volts on the heaters. All in all I'm very pleased with the purchase, and look forward to getting it operational.

Last night I pulled the front glass off and cleaned the CRT. It looks a lot different than other 21AXP22 tubes, the phosphor has a different color to it.

Actually Nick,
Your 21-CT-55 is more rare than the CT-100. Fewer were built and, as far as we know, even fewer survive. Nice catch. I was a bit stunned when you raised your hand with the winning bid.

-Steve D.

Yes, the numbers say they are more rare. I do believe that because the CT-100 is a more well known set, it is more sought after. Maybe that's why people aren't really searching for the 21-CT-55 as much as the CT-100?

I was surprized to have the winning bid as well, though to be honest I had no idea what would happen when the auction began. If anything, I figured the same thing would happen as with that Motorola set that went for $10k last year on Ebay: I bid but had no expectation of actually winning.

What ended up happening was the night before I told myself I won't get another opportunity to own a set like this, and since I was definitely interested, I sat down and hammered out a maximum bid that I could reasonably pay off. That number ended up being $4500. When the bidding stopped I hadn't yet reached $4500, and I won the set. I was really expecting more action on it, and initially I figured I'd get outbid very fast. But I think people were more interested in the CBS and Zenith sets, so since the 21-CT-55 came before those, they saved their money. I suppose the auction would have been very different if the set had come after the Zenith and CBS ones. As always, there's the luck factor...

In any event, I'm very happy to have it and I will make every effort to make this a first rate set. Right now I'm just doing some cursory cleaning, the electronic stuff will come farther down the road.

Nick:

What was the date on your chassis? I looked at it but did not write it down. The date written on my chassis is 1-7-55. If I remember yours was also January of '55.

Steve

Mine says 1-17-55, born only 10 days apart! lol

Congratulations... I am sure the set will be just fantastic when you are finished ... drooool!!!!!!

I can't wait to see that set working!! I also can't wait for my back to stop hurting from carrying it up three flights of stairs with you the other day:sigh: :D

Yeah, that was a b!tch wasn't it?

When a set is back pain/cannot move it on my own heavy I generally remove the chassis and CRT and move it in a several trips (especially when stairs are involved).

Good luck getting it working!

Tom C.

Yeah, that was a b!tch wasn't it?

Yeah, but it was worth it :yes: If there's anything that you decide to never sell, let it be this set. (unless, it's to me of course:D :deal:)

Hours of fun ahead -- I am envious. I sometimes get impatient when working on a project, but if one of these fell into my hands, I'd force myself to slow down and enjoy it. Could be a long time before you find another.

Phil Nelson

unless, it's to me of course :D :deal:



Only if the Wingate is part of the deal! :yes:

Agreed.
Last night I pulled the front glass off and cleaned the CRT. It looks a lot different than other 21AXP22 tubes, the phosphor has a different color to it.

Now, that's odd. Different how? How different? Might be worthwhile to demount it sometime and look for labels.

There are at least 2 variants of he 21AXP22... one has a paper-white appearance to he phosphor screen, the other a somewhat greener hue. But I don't know how or if this affects the colorimetry of the CRT

It's hard to explain. You know how a 21AXP22 normally has a whitish grey look to it, like the CYP tubes do? This one has a slight, I don't know, almost greenish hue to it. You have to have another AXP right next to it to see the difference.

there are 2 21axp22s here in columbus.i saw them last week.former repair man that passed and family has some very nice items to sell.one has a green tint to it.it checks like new and it will be sold on ebay.the other has a bluish tint and also checks well.there will be some nice b/w sets and a few roundies.ctc7 and 9,zenith roundie,admiral roundie and a partial dumont roundie.looks like rca clone.the axps would be a nice scores.the 7 and 9 are complete,working with decent cabinets.the 7 has doors on the front.they need a good cleaning and minimal touch up.since this is family-i cant buy any of these items.george was a good man and ran a shop for years in the southend.check ebay as his children are all in agreement to sell them this way.

It's hard to explain. You know how a 21AXP22 normally has a whitish grey look to it, like the CYP tubes do? This one has a slight, I don't know, almost greenish hue to it. You have to have another AXP right next to it to see the difference.

The one in my 4 also has a greenish hue to the screen, as opposed to the greyish color of most other 21AX's. Maybe an early phosphor gamut. Mine isn't really bright, but the color reproduction can be spectacular. See avatar.
Kevin

It's hard to explain. You know how a 21AXP22 normally has a whitish grey look to it, like the CYP tubes do? This one has a slight, I don't know, almost greenish hue to it. You have to have another AXP right next to it to see the difference.

Nick,

The only 21AX's that have this greenish color phosphor have been mostly found in CT55's. I also have a very early CTC4 which has a 21AX with a greenish looking face. Another intresting discovery is that, at least on the crt from my 55, which was rebuilt by Hawkeye, RCA was using up the 20 pin stems left over from the production of 15GP22's, rather than using a 14pin stem as would normally be expected. Take a close look at the stem on your tube. See if you can count the number of wires by looking into the end of the neck through the neck glass. The old gun removed from my 21AX was mounted on a 20 pin 15G stem.

All this leads us to believe that the initial production run of 21AX tubes, which were used in the CT55 sets, and which have this greenish color phosphor, may be using the full gamut phosphors like were used in the 15GP22 tubes. Some day we will need to test one of these green faced 21AX tubes with a colorimiter to see if they are indeed full gamut or not.

CT55's are known for having a brilliant color picture. Perhaps full gamut phosphors are part of the reason for this. AFter all a CT55 is actually a CT100 with a 21" crt and a modified HV section. Perhaps the phosphors are also an extension of the CT100 series.

Time and further investigation will reveal the answer.

Bob

See if you can count the number of wires by looking into the end of the neck through the neck glass. The old gun removed from my 21AX was mounted on a 20 pin 15G stem.

I just went to look, and from what I can see it has the same number of pins the base does. But this particular tube was made very late in '54, so it's not like it's from the initial run or anything. In fact, the code 4-52 indicates it was made during the last week of '54.

All this leads us to believe that the initial production run of 21AX tubes, which were used in the CT55 sets and which have this greenish color phosphor, may be using the full gamut phosphors like were used in the 15GP22 tubes. Some day we will need to test one of these green faced 21AX tubes with a colorimiter to see if they are indeed full gamut or not.


Sounds like another interesting project for a failed tube, obvisouly we would not want to destroy a rebuildable one. What is involved in the testing? Are samples taken of the actual phosphor, or just the light given off by it when excited? The observation makes sense, the screen has the same kind of look that a 15GP22 does with a little bit of sparkle I can't quite put my finger on.


CT55's are known for having a brilliant color picture. Perhaps full gamut phosphors are part of the reason for this. After all, a CT55 is actually a CT100 with a 21" crt and a modified HV section. Perhaps the phosphors are also an extension of the CT100 series.


That's what I've always thought, but now the expert has confirmed! :smoke:

The gamut has to be measured by the light from an operating tube. Chemical analysis would require smashing the tube - not recommended!

Up until I saw this comment, I thought all 21AX's used the same phosphors as the 15G. There are two defining characteristics of the 15G phosphors: the blue is true NTSC blue (more cyan and less violet than modern tubes), and most important, the green is P1, less yellow than the later sulfide or cadmium sulfide green. (And, of course, the red is not very efficient.) The question is which phosphor or phosphors were changed in the 21AX's that changed the face color. If it was the red phosphor, it might be hard to determine, as most of the red phosphors used over the years fluoresced in about the same color, until the cadmium sulfide red in the all-sulfide tube. This phosphor was strongly colored under ambient light, resulting in a fairly strong green face color, and also its emission turned orangy under high beam current. The all-sulfide tube (including sulfide blue) could not be made until techniques to prevent contamination were developed. Contamination of the blue sulfide by copper would turn it into a green phosphor. The uncontaminated blue is more deep blue than than NTSC specs, and is what we have today.

It would be interesting to see the different blends of phosphor used over the years ploted on the color spectrum horse shoe(I can't recall the right name) for comparison.

Tom C.

The gamut has to be measured by the light from an operating tube. Chemical analysis would require smashing the tube - not recommended!

Interesting. So would I be right in assuming the piece of gear to make such a measurement is quite expensive? I wonder if some university somehwere would have one I can borrow? I currently have both ilk of AXP tube, and I'm dying to put the 'phosphor' debate to rest once and for all!

What I'm really shooting for is to get a light sample from all types of tube, so we have a reference. Currently I have the 2 AXP's, a green FBP, a green FJP (sans lens), and a pair of grey faced CYP tubes for comparison. One of the CYP's is an 'A' version, not sure if that matters or not. That's the reason for the investigation.

So the greenish (early version) would be the 21AXP22 and the later version (whitish) would be 21AXP22A? This has been eluded to before but it would be good to clear that up.

So the greenish (early version) would be the 21AXP22 and the later version (whitish) would be 21AXP22A? This has been eluded to before but it would be good to clear that up.

Therein lies the rub.

I've seen 21AXP22 and 21AXP22A tubes that are grey faced, the only difference noted in the data sheets being the addition of a resistive inner coating for arcing protection for the 'A' version. As pointed out by yoda, the early 21AXP22 tubes with greenish phosphor colors on their face are likely related to the 15GP22. It's thought to be the result of RCA wanting the 21" version of set (21-CT-55) to be just like the earlier 15" one (CT-100), though no definitive proof exists to my knowledge. It's all conjecture by the collecting community at this point.

Furthermore, the change of phosphor was likely related to light output. As I understand it, customers complained of dim tubes so RCA set out to make some improvement. Perhaps this is why early AXP's are green like the 15GP22, while later ones are grey? Changes like this continued throughout the roudie's life, eventually leading to the very bright FJP/FBJ line of picture tubes. While they did not produce colors as accurately as the early ones, obvisouly customers were willing to trade off some loss in color fidelity for a bump in brightness. This also explains the changes in circuitry, since there's no point in decoding the NTSC signal exactly if you're not going to reproduce the picture on a tube that gives 'true' colors. Cost was also a big factor in those times, so it's a real chicken vs egg scenario.


In any event, some day I'd like to get my hands on the instrument used to make such measurements. That way I can test all versions of tube, in order to figure out what phosphors were used in which version of tube. Then we can make definitive statements about the tubes, instead of wondering 'why?'

Interesting. So would I be right in assuming the piece of gear to make such a measurement is quite expensive?

Nick,

Actually there is a colirimiter that attaches to a laptop. A couple of the collectors have one. I think it was about $200. I would bet Cliff Benham owns one. I would email him and see what he has to say about it.

I believe that Cliff and John Folsom tested a tube at John's house some time back using the device.

Bob

Nick,

Actually there is a colirimiter that attaches to a laptop. A couple of the collectors have one. I think it was about $200. I would bet Cliff Benham owns one. I would email him and see what he has to say about it.

I believe that Cliff and John Folsom tested a tube at John's house some time back using the device.

Bob

Or, you might want a spectrometer like this one (http://www.vendio.com/stores/endlesssupplies/item?lid=8370541&source=Vendio:Google%20Product%20Search) which measures the actual intensity vs wavelength rather than giving you RBG values like a colorimeter does.

John

Interesting. So would I be right in assuming the piece of gear to make such a measurement is quite expensive? I wonder if some university somehwere would have one I can borrow? I currently have both ilk of AXP tube, and I'm dying to put the 'phosphor' debate to rest once and for all!

What I'm really shooting for is to get a light sample from all types of tube, so we have a reference. Currently I have the 2 AXP's, a green FBP, a green FJP (sans lens), and a pair of grey faced CYP tubes for comparison. One of the CYP's is an 'A' version, not sure if that matters or not. That's the reason for the investigation.

I and some others have a Spyder 3 colorimeter, which is fairly good as colorimeters go, but not to be relied on for fine differences in the red phosphors, as their spectra varied the most with different formulations (rare earth vs. non-rare earth, for example). Cliff also has an "Eye_one" or "I1" spectroradiometer, which will give a true reading despite the spiky spectrum of rare-earth phosphors or the variations in bandwidth of the others. I believe the Spyder 3 is in the $200 or so range these days (haven't looked lately), while the spectroradiometer starts at around $1000 and up depending on what software you license with it. Packages range form monitor only to full printer/monitor/scanner workflow profiling and calibration. They keep changing the packages each year. It is also sold by Spectracal with a TV/home theater calibration software package. Used ones sometimes go for as little as half price, but usually more like $800, and are often missing parts of the kit. I would like to have one, but haven't seen one at the price and condition I would like, so I get along with the Spyder 3, which has been just fine for calibrating my computer monitors.

By the way, when you measure a tube, you get the operational color, not the pure phosphor color, because any imperfections in the color purity settings, light scattering, electron scattering, etc. are all included.

Nick, <---> I believe that Cliff and John Folsom tested a tube at John's house some time back using the device.
Bob

We did test several tubes including a 21AXP22. Attached are several different
charts and graphs: The first is the spectrum response of the 21AXP22 taken with the EYE-ONE Pro Spectroradiometer. This is a gray faced tube as I remember. The second and third are both CIE charts comparing the color
coordinates, some measured and some published, of various color sources and
defined colors. Disregard "RX43" in the title of the third one.

Hope this helps answer some of the questions. Cliff

Wow, outstanding work!

Looks like they are pretty close, for the most part. I'd bet the later tubes are farther apart than the early ones, have you tested any of them?

Wow, outstanding work!

Looks like they are pretty close, for the most part. I'd bet the later tubes are farther apart than the early ones, have you tested any of them?

Here are the spectrum charts for the 15GP22 and a rare earth Mitsubishi tube at the ETF Museum. Please note that the vertical scale for the 15GP22 is different than that of the 21AXP22 and the rare earth tube. That's why it appears to be very low when in fact it is close to the 21AXP22.

By the way, when you measure a tube, you get the operational color, not the pure phosphor color, because any imperfections in the color purity settings, light scattering, electron scattering, etc. are all included.

Armed with old instrumentation experience [as a kid I worked for an instrument manufacturer for some years doing initial power-up, troubleshooting, test, and calibration] and when the Spyder calorimeter became known a few years ago, I made some measurements of a near-pristine 15GP22. I particularly considered purity, ambient light, and repeatability when making the 'operational color' measurements.

For example, I took measurements at screen locations that exhibited the best purity. All readings were made with a dark cloth over the set.

Results did support the 15GP22's reputation for gamut. Only the green fell a bit short of the 0.21, 0.71 1953 NTSC standard. But not by much.

At the time, John Folsom platted the results on a graphic that included the 1951 CBS and 1953 NTSC, and I believe the sRGB standards. As I am in SC visiting relatives after the ETF convention, I unfortunately do not have access to the graphic at this time.

For me, this was one step in the quest to reproduce what one would have seen in the early days of color television. Wayne Bretl has demonstrated mathematically that the TK-41 was capable of generating a 1953 NTSC compliant image. Now if we can only get Mrs. Astaire to allow us a DVD of her husband's restored October '58 special, we could demo the real thing at the next ETF convention...

Pete

Wow, outstanding work!

Looks like they are pretty close, for the most part. I'd bet the later tubes are farther apart than the early ones, have you tested any of them?

The 1931 CIE chart shown exaggerates the difference in green and minimizes it in blue. The difference between the CBS blue and others is as significant as the difference in green between the SMPTE and others. There is an alternate plot developed in 1976 that is closer to uniform variation.

Here are the two versions of the plot (1931, x,y; 1976 u',v') comparing several color gamuts:


Technicolor at three different dye concentrations
(Many thanks to Ed Reitan for supplying the dye spectral curves used to calculate these colors);

NTSC;
sRGB (digital still cameras and HDTV);
Fujichrome test target;
Kodachrome test target;
Pointer's surface colors (a survey of the range of natural, paint, and printed colors).

Note the more significant differences in the blue and magenta region shown on the u', v' diagram.

Here are the spectrum charts for the 15GP22 and a rare earth Mitsubishi tube at the ETF Museum. Please note that the vertical scale for the 15GP22 is different than that of the 21AXP22 and the rare earth tube. That's why it appears to be very low when in fact it is close to the 21AXP22.

The spectrum from the Eye-one has 10 nm resolution, which is good enough for color calculations, but does not show how spiky the rare earth red is.

This page has a finer resolution plot of the individual phosphors in a modern tube, about 20% down the page:
http://www.websters-online-dictionary.org/definitions/phosphor?cx=partner-pub-0939450753529744%3Av0qd01-tdlq&cof=FORID%3A9&ie=UTF-8&q=phosphor&sa=Search#922

By the way, when you measure a tube, you get the operational color, not the pure phosphor color, because any imperfections in the color purity settings, light scattering, electron scattering, etc. are all included.

Armed with old instrumentation experience [as a kid I worked for an instrument manufacturer doing initial power-up, troubleshooting, test, and calibration] and when the Spyder calorimeter became known a few years ago, I made some measurements of a near-pristine 15GP22. I particularly considered purity, ambient light, and repeatability when making the 'operational color' measurements.

For example, I took measurements at screen locations that exhibited the best purity. All readings were made with a large dark cloth over the set.

Results did support the 15GP22's reputation for gamut. nly the green fell a bit short of the 0.21, 0.71 1953 NTSC standard. But not by much.

At the time, John Folsom plotted the results on a graphic that included the 1951 CBS and 1953 NTSC and I believe the sRGB standards. As I am in SC visiting relatives after the ETF convention, I unfortunately do not have access to the graphic at this time.

For me, this was one step in the quest to reproduce what one would have seen in the early days of color television. Wayne Bretl has demonstrated mathematically that the TK-41 was capable of generating a 1953 NTSC compliant image. Now if we can only get Mrs. Astaire to allow us a DVD of her husband's restored October '58 special, we could demo the real thing at the next ETF convention...

Pete

Double post?

I took measurements at screen locations that exhibited the best purity. All readings were made with a large dark cloth over the set.

Results did support the 15GP22's reputation for gamut. nly the green fell a bit short of the 0.21, 0.71 1953 NTSC standard. But not by much. Pete

One other set of data that should be helpful in visualizing the gamut of P22 phosphors is from the RCA HB-3 Tube manual, 1964.
Cliff

One other set of data that should be helpful in visualizing the gamut of P22 phosphors is from the RCA HB-3 Tube manual, 1964.
Cliff

Wow - thanks, Cliff - I never saw that combined comparison data sheet before.

Wow - thanks, Cliff - I never saw that combined comparison data sheet before.

That material came out of an HB-3 manual I got at Kutztown from John Timinsky. It came from RCA Labs and was the property of Al C. Schroeder.
I'm kind of proud to own it. #;^) Cliff

Sweet info, Cliff! We'll have to get back into this once I have the thing up and running, which it surely has not done recently...


because now...


The peaking coil replacement odyssey begins. :sigh:


Lots of bad ones, and my attempt at repair was not met with success. There's just too much damage done by the corrosion intrusion, and though I was able to peel the plaster shell off one, it also peeled some fine copper wires along with it.

BTW- I don't follow the notation of inductance in the schematic. MH is obvious- millihenries. I am assuming mu-h is literally μ spelled out- microhenries in other words.

Hu- You know there's some funny stuff in yer graphs...... In the "15gp22-21axp22.pdf" that includes "RX43" in the on screen title. The 15gp22 actually has a narrower color spectrum than the 21axp22, and much narrower than p22 phosporous. Smaller triangles on the graph do actually indicate narrower color spectrum. And on the measured graphs both the 15gp, and the 21axp seem to have a very similar shape, except for the brightness level. (You notice in the old RCA p22 graphs also put up on this thread RCA correctly uses the term "relative" in its brightness scale, the vertical left scale. Relative in this case is kind or normalizing with refrence to brightness.) For actual more acurate comparison you are going to have to measure both, or all tubes you compare at very similar brightness levels. (or beam currents, Something I took exception to when this discussion took place many years ago on Pete's private site.) You will get very hard to distinguish readings using those scales with such wide differences in light levels. Think about reading 2V acurately on an analog meter when you chose to use the 400V full scale deflection setting. And you also have to first establish that your instrument has a flat response across the full spectrum. And in addition, that the instrument is accurate across all light intensity levels. And as for the overall screen face color, it may just be the difference in the material between the phosphorous pigment, or in the material used to hold the phosphorous in suspension when deposited on the screen. Anyway just a squirrels thought on the presented data.

And while were on the subject, I was also wondering just what it would be like to set tube purity adjustments using live readings and that fancy color measuring device. After all its been proven in the design of color sets, and in VCR design that our eyes are very very easy to fool. So howbout it you guys ever think of setting purity with that fancy color thing and then doing color spectrum measurement? It sure would be cool if a computer set purity and not our eye..... (Dam that squirrel)

And while were on the subject, I was also wondering just what it would be like to set tube purity adjustments using live readings and that fancy color measuring device. After all its been proven in the design of color sets, and in VCR design that our eyes are very very easy to fool. So howbout it you guys ever think of setting purity with that fancy color thing and then doing color spectrum measurement? It sure would be cool if a computer set purity and not our eye..... (Dam that squirrel)

Those "fancy devices" are much too slow to use for adjusting purity. For that you would need a fast-responding (though less accurate) device. Plus, you would need a multi-headed device that reads center, edge, and corner areas simultaneously. Only the production factory could afford such special instrumentation. In the home, the eye is the best instrumetn for adjusting purity.

Hu- You know there's some funny stuff in yer graphs...... In the "15gp22-21axp22.pdf" that includes "RX43" in the on screen title. The 15gp22 actually has a narrower color spectrum than the 21axp22, and much narrower than p22 phosporous. Smaller triangles on the graph do actually indicate narrower color spectrum. And on the measured graphs both the 15gp, and the 21axp seem to have a very similar shape, except for the brightness level. (You notice in the old RCA p22 graphs also put up on this thread RCA correctly uses the term "relative" in its brightness scale, the vertical left scale. Relative in this case is kind or normalizing with refrence to brightness.) For actual more acurate comparison you are going to have to measure both, or all tubes you compare at very similar brightness levels. (or beam currents, Something I took exception to when this discussion took place many years ago on Pete's private site.) You will get very hard to distinguish readings using those scales with such wide differences in light levels. Think about reading 2V acurately on an analog meter when you chose to use the 400V full scale deflection setting. And you also have to first establish that your instrument has a flat response across the full spectrum. And in addition, that the instrument is accurate across all light intensity levels. And as for the overall screen face color, it may just be the difference in the material between the phosphorous pigment, or in the material used to hold the phosphorous in suspension when deposited on the screen. Anyway just a squirrels thought on the presented data.

P22 refers to any RGB color tube. The points shown are some particular set of phosphors, which appears to have the later non-NTSC blue. Cliff maybe can tell us the source of the numbers, which may be ideal phosphor numbers or measurements with a colorimeter rather than a spectroradiometer.
The reduced purity in the 15GP22 tube is to be expected. Later techniques for reducing electron scatter, etc. had not been invented yet. Specifically, the green is very close to where it should be, the blue is close to NTSC blue, which is not as violet as later blue phosphors. The only real degradation is in the red, indicating the red purity was not ideal. Also, maybe Cliff can comment on whether these numbers came from a spectroradiometer, or a colorimeter. If a colorimeter, errors are also to be expected.

I talked with the president of Spectracal at the Hollywood Post Alliance in February, and he said that the I-1 spectroradiometer is much more accurate than colorimeters, and is reasonably comparable to much more expensive spectroradiometers. Of course, this non-lab model, costing about 1/10 of the top ones, is only calibrated once, at the factory, whereas a lab instrument would be calibrated yearly or more often to a NIST-traceable standard. The important thing is that it can correctly handle the red primary spectrum that trails off into the infrared. Back when we first measured Cliff's field-sequential color wheels on a CRT with the Spyder II colorimeter, we got wildly wrong results due to the deviation of the deep red response from the standard observer curves. The Spyder III improved that considerably, but only the I-1 gives results that are really close to eyeball color.

On the good color bars displayed on my reactivated 21CT55, yellow is best ever while the red is much truer red then the '97 27in Sony which is distinctly orange/red! My two 21FBP22's have differently unenergized phosphor screens. The one in the 21CT55 has a light gray tone while my spare has a greenish tone. My Sony pro monitor has SMPTE-C spec'ed phosphors. Its red is more accurate, not as pure red as the 21CT55, but close. I read somewhere the modern SMPTE phosphors are more orange/red since they produce better "flesh tones" with less accurate chroma demodulators. So anyway, I designate the gray screen CRT as a "rare-earth" 21FBP22A and the green screen CRT as a sulfide 21FBP22. It would be very interesting to see real-time side by side displays of the color bars produced by the NTSC 15GP22 / 21AXP22 and the gray and green screen 21FBP22's.

Here is my CTC-7 with grey faced 21CYP22, with Philco 21FBP22 green faced tube sitting on top. The monitor to the right is a Sony security monitor, with NTSC comb filter decoder.

http://www.videokarma.org/showthread.php?p=2998927


Grey faced 21AXP22 has similar color to the CYP tube, where anything with a green sulfide set of phosphors looks more orange-red than true red to my eye. We'll see what the green faced 21AXP22 in the CT-55 ends up looking like, I assume it will have similar response to a 15G.

Nick,

I guarantee you it will be nothing short of DAZZLING! I hope some day you can get up here with Mark (he needs to make a trip to get his 21" roundie safety glass) so you can see first hand what a wonderful picture a CT55 will produce. But Murphy's law says if you come by it will blow a fuse.

Bob

[QUOTE=Tomcomm;3003530]...I read somewhere the modern SMPTE phosphors are more orange/red since they produce better "flesh tones" with less accurate chroma demodulators...QUOTE]

I was on the SMPTE monitor committee, and I can tell you that the colors were standardized based on what was available in the tubes made with controlled phosphor batches and supplied in Conrac monitors. In "SMPTE C primaries," the "C" stands for Conrac. The relatively slight variations in red phosphors over the years has little effect on flesh tones compared to the changes in green and blue, especially green.

In "SMPTE C primaries," the "C" stands for Conrac.

I didn't know that.
Sitting on that committee must have been a very interesting time. #;^)
Cliff

Here is my CTC-7 with grey faced 21CYP22, with Philco 21FBP22 green faced tube sitting on top. The monitor to the right is a Sony security monitor, with NTSC comb filter decoder.

http://www.videokarma.org/showthread.php?p=2998927


Grey faced 21AXP22 has similar color to the CYP tube, where anything with a green sulfide set of phosphors looks more orange-red than true red to my eye. We'll see what the green faced 21AXP22 in the CT-55 ends up looking like, I assume it will have similar response to a 15G.

When you have a variety of tubes running, we can measure them with the Spyder 3. It may not be as accurate as the spectroradiometer, but it should indicate the direction of the differences.

That's the plan, anyway.

What I want to do is have the green AXP, grey AXP, CYP, and green FBP all measured. I have date codes for all of them, so it will be interesting to see the progression of phosphors through the years. Ultimately I would like to have a database of them all built up, so we can see what response they have in order to shed some light on the exact colors a person will see when they use a certain tube in their set.

That way, we can replace subjective things (what people's eyes are seeing) with something objective and concrete (at least within the limits of the instrument). Only then will we be able to say 'tube x does in fact have an orange-reddish phosphor, where tube y has a more correct color.'

Double post?

Sorry about that. Was on the road after ETF and just now saw the X2 flub,

Pete

I think testing all those tubes would be a good idea. But you should test in a way that normalizes all the tubes. For example, use a simple light meter to set all the tubes to the same or very near the same overall brightness level. Use the same method to make a white screen on all the sets. You would have to use the same equipment on the test of each tube. I think it would also be neato to include some of the 23" and 25" tubes from the 60's through the end of crt production in the tests as well.

you should test in a way that normalizes all the tubes. For example, use a simple light meter to set all the tubes to the same or very near the same overall brightness level. Use the same method to make a white screen on all the sets.



All the tubes would have proper greyscale tracking before the test, along with purity and the whole bit. Every effort will be made to ensure a valid test occurs.

Just got outbid on a used I1 spectroradiometer on ebay - would have been a good price if it sold where I stopped. Maybe some other time...

That sucks. Oh well, this is already going to happen it's just a matter of when!

Back to the subject at hand...


I recently discovered that I hate metal polishing. :thumbsdn:

But I can't argue with the results. The trim around the CRT window is badly tarnished, so I set about fixing it. First I tried a buffing wheel and compound, but that didn't even faze it. The stuff is just too old, and covers 100% of the trim. Plan B- I wet down some paper towels with vinegar, and draped them over the trim overnight. It looked like hammered dog crap when I woke up, but some polishing stuff buffed the light surface corrosion right off. After that, I hit it with some Never Dull and holy cripes does it look good now! I mean, it's literally a MIRROR SHINE. It's gonna take many more hours of work to get the rest of the trim pieces done, but results like this are well worth it in my book.

Think it's a good idea to hit it with clear laquer after I'm done? I don't want to do this every year...

Apologies for the pics, they don't do the brass justice. A shine like this is hard to capture with a camera.

Clear lacquer can keep brass nice for a long time. It may be a little trickier to spray lacquer on shiny metal than on wood. Little uh-ohs jump out at you.

This may sound nutty, but wax can also be used. When I had a guy restore some antique light sconces, he added a couple of little new switches. He dipped those in gun bluing to make an aged color and then used Howard's Feed 'n Wax over all of the brass, old and new. I was skeptical, but this was about 10 years ago, and they look exactly the same.

Phil Nelson

Lookin' good Nick! That trim looks new!!

Nick,

Although this method does not produce a Bright High Mirror shine, this is what I do.

To get a nice brushed satin finish, I remove the tarnish and corrosion using 3M Scotch bright wheels on a polishing arbor. It leaves the finish looking like it has been buffed with steel wool, sort of a satin finish. This process takes about 1 hour on the polishinhg arbor for the exact same trim as on your 21CT55. I did the trim for the Hallicrafters CTC4 clone in just this manor yesterday.

If you however want a higher luster, the next step is to hit it with 0000 steel wool. Then I always spray with clear nitroceluolose lacquer. I have also used clear ACE brand enamel from Ace hardware with good results. The Ace brand leaves a heavier coat, but it is a bit trickier to work with on a high luster finish.

The trim I polished up yesterday had been subjected to moisture over a long period of time. As a result there are microscopic pits in the surface that are the color of copper. (brass is mostly copper, usually 90% or more) The tiny pits show up more if the surface is polished to a bright luster mirror finish so, I dedided to use a brushed satin finish because it looked better and the pits are less noticable.

I am not sure what the correct finish is. Is it a bright mirror finish or a brushed satin finish? In any event I have used the brushed satin finish on a couple other sets and it looks quite nice.

Bob

More progress, but my polishing wrist is starting to ache! :D

Only one more trim piece to go, but it has a dent. What's the best way to pop a dent out of these things? I'm tempted to leave it be, and install it up top where it will be less noticeable.

I'm tempted to leave it be, and install it up top where it will be less noticeable.
I'm glad you mentioned that. The bottom trim piece on my CTC-7 has a couple of little dents, and I was wondering how to deal with them. I just trotted out to the shop and confirmed that the top piece is perfect. Problem solved!

Phil Nelson

I don't know if it is just me. But I cannot see the dents!
Can you highlight them on your photo?:saywhat:

The dent is in the last piece, which is currently soaking in vinegar. I'll post the dents tomorrow, they are very noticable.

Here's a shot of the trim, all polished up now! The dented (and bent) piece is up top, it's not so noticable now. It will be livable till I can find a better one. Also got a wild hair to polish the CTC-4 stuff, since I never did any clean up to it. Sure looks nice in it's new digs in the living room. :drool:

Ugh ! That trim piece is AWFUL ! RUINS the whole thing ! For SHAME !! Box the ENTIRE set up & send it to me, & I promise I'll dispose of it so it'll NEVER defile anyone's eyes w/its hideous ugliness again...(grin) Lemme put it to ya this way-If someone offered me a brand-new, TOTL Mustang w/everything you could get on it, or one of your TVs, I wouldn't hesitate an instant. I'd grab the TV so quick it'd make yr head spin...

Yeah well, who wants a Rustang anyway! lol

That's why I like sites like this, we can always live vicariously through each other.

Yeah well, who wants a Rustang anyway! lol

That's why I like sites like this, we can always live vicariously through each other.

She-it, there's barely enuff metal on one of 'em anymore TO rust...(grin)

I'm glad you mentioned that. The bottom trim piece on my CTC-7 has a couple of little dents, and I was wondering how to deal with them. I just trotted out to the shop and confirmed that the top piece is perfect. Problem solved!

Phil Nelson

I use a spoon shaped dental tool from the back side of the brass trim piece. Place the front side of the brass trim against a hard flat surface like your kitchen counter top. Use the spoon shaped dental tool to press against the brass and move back and forth over the dent to to flaten out the dent against the hard counter top. This brass is very thin and is easily formed back into place with a small amount of pressure from the back side. This is a method similar to the way auto body mechanics straighten a dent using a dolly and a planishing hammer. The counter becomes the dolly and the dental spoon is your hammer (but you don't hammer you just apply pressure and slide the spoon back and forth)

I was able to almost completely remove 2 small dents with this methodology, and you have to look very closely now to find them.

Good Luck!

Nice! Nice! Nice!

Thanks, Wayne! very soon, we may be watching Oz on it...

Digikey package arrived today, that means it's time for a peaking coil party!

Operation 'I hate 21-CT-55 peaking coils' was a success, but it remains to be seen if the new ones will do what they are supposed to.

Slowly powered the chassis on the variac (how did I ever troubleshoot without one?!?), and only got 20 volts of B+....

Predictably, both of the caps in the doubler are almost completely open leading to very low voltage. Jumpered one of them with a new cap, and got almost full voltage and a decent looking waveform out of the horizontal oscilator!

Now the recapping begins...

That leaves me with a lingering question though: why on God's green Earth would the PO have replaced almost all the caps in this thing, only to not replace the ones that matter most? I always begin with the power supply when it comes to caps, but it appears the opposite happened here.

Muhahaha, there are signs of life!

:banana:

Good news, keep at it!

It lives.

:banana:

amazing .wonderful ... wonder when she was last on...congrats !!!!

Oh. Em. Gee.

Nice work, man.

Phil Nelson

This set was in the collection of Danny Gustafson, who had many of the sets he owned restored by Dave Johnson. That may explain why it came up so easily.

Very nice!

excellent!

This set was in the collection of Danny Gustafson, who had many of the sets he owned restored by Dave Johnson. That may explain why it came up so easily.

That is my belief as well, Steve. Most of the lytics had previously been replaced, except for the PS ones I just did.

Thank you, everyone. This set will be very enjoyable, I plan to own it for a very long time. I ran into a little problem last night where it would received color, but the luma channel was d-e-d DEAD. For some strange reason, the 2nd video tube plate was at 0 volts and I couldn't figure out why. I disconnected the parallel coil and resistor going to the matrix and it popped back up to normal showing luma bars on the scope, and when I reconnected it was working. It's still working as of this morning, so it's some kinda phantom or self induced gripe. Probably dislodged a bead of solder or something.

Anyhow, the raster is slightly tiled so next up is screen geometry and convergence.

Thanks, Mal. I knew you most of all were waiting to see this. :thmbsp:

Oh-OH - now all the neighbors will want to come over & watch Bonanza!

Don't know if I've said it yet, so-
AH HATE Yew !! -Yosemite Sam, Esq. (grin)
Seriuosly, EXCELLENT job...

Very nice!

Yep!

As for the conversation we had concerning the coils: I ended up buying ferrite core inductors from Digikey to replace all the old ones, despite your advice to stick with phenolic cores. It seems to work pretty well though, so I don't think I'm going to mess with it. Reason being is coils that are close to original in design with correct core material ect are hard to find, and I didn't feel much like going through 3 different companies to get them all.

Good thing is I bought 2 complete sets of inductors for this chassis in case something went wrong, so if anyone needs a bag of inductors to do a complete replacement job I have them. They are all marked for where they go on the chassis, to make the task a little easier. If you guys would like, I can post up the Digikey parts numbers and quantities so you can order for yourselves. Meantime, I'm going to post the set of coils I have in the classifieds. Hopefully someone needs them.

Congradulations!

You're on the home stertch.

Tom C.

I restored lots of sets for Danny. This was not one he ever had working.
The 21CT55 he watched was the toated mahagony set that was sold years ago.
To my knowledge Danny never turned this one on. I don't know who he
bought it from.

Awesome! I gotta come see it now!!

Yep!

As for the conversation we had concerning the coils: I ended up buying ferrite core inductors from Digikey to replace all the old ones, despite your advice to stick with phenolic cores. It seems to work pretty well though, so I don't think I'm going to mess with it. Reason being is coils that are close to original in design with correct core material ect are hard to find, and I didn't feel much like going through 3 different companies to get them all.

Good thing is I bought 2 complete sets of inductors for this chassis in case something went wrong, so if anyone needs a bag of inductors to do a complete replacement job I have them. They are all marked for where they go on the chassis, to make the task a little easier. If you guys would like, I can post up the Digikey parts numbers and quantities so you can order for yourselves. Meantime, I'm going to post the set of coils I have in the classifieds. Hopefully someone needs them.

I'm about to make a big cap order which will include parts for my 21CT55. I'd really like those part numbers so I can put the peaking coils on order too (without going to the work of specking coils out myself).

I'm also trying to find info on what to use for series resistors to compensate for the lower resistance of the silicone I plan to replace the selenium rectifiers with.

Edit: found the info here: http://www.videokarma.org/showpost.php?p=3114722&postcount=9

I have the CT-100 coil list around here somewhere, whoch should be identical or pretty damn close. Keep in mind that those little white inductors have a different Q than the modern replacements and that can have an effect on performance.

I'll go look through my file cabinets when I get home.

As for your second question, I have to answer that with a question: do you plan on running the set right off a wall plug, or do you plan to only run it on a variac or Sola at say 115 or 117 VAC?

I highly recommend you hold the line voltage to 115 or 117 volts whenever running the set, and calculating the new dropping resistors for 115 or 117 volts.

You can, however, calculate the new droppers for whatever the line voltage is in your neck of the woods, say 122 VAC or whatever.

Small changes in line voltage creates a larger swing in B+, and the 21-CT-55 flyback already has a tendency to overheat and burn up. Whatever you do, make sure the droppers are sufficiently sized, and the horizontal section has been completely checked before moving on to other areas of the restoration. I'd hate to see your fly smoked from B+ that was a touch too high.

A few hours ago I found Nick's coil list and edited my post to reflect that.

I've got a 1KVA VRT isolation trans waiting for it. I may put a variac in series to set the line voltage if I don't like what the VRT is putting out. The mains voltage here varies a bit so most tube sets end up run off a VRT anyway.

It will be a while before I get to working on or finishing this set. Plan is to order enough parts for several sets (some of which may be done first), plus replenish my cap stocks to nominal quantities, as a winter stock up. I'm seriously considering restuffing all the caps in the 21CT55 which is going to take time as is checking everything over before power up. As with any early color set with an unobtainium flyback there are going to be a lot meters on it for the first power up with the H out tube connected.

I don't restuff as I feel there are few, if any sets, truly worth the effort. To each his own though...


About the inductors, the original white ones are obviously the best fit electrically. Check them and any that aren't open, leave. Some more may open during the restoration, but if any survive, they're worth keeping in my opinion given my experiences with my CT-100 (now John's).

Not sure what troubles you had, but this is my Merrill after total inductor replacement with the new ones from the list I put together. Looked pretty good to me.

http://miniman82.mysite.com/images/CT-100/IMGP5210.JPG

Crappy picture and there’s a hint of a drive line, but the color was stunning.

I've got a 1KVA VRT isolation trans waiting for it. I may put a variac in series to set the line voltage if I don't like what the VRT is putting out. The mains voltage here varies a bit so most tube sets end up run off a VRT anyway. You should get one of these for each of your sets.

http://www.antiqueradios.com/forums/download/file.php?id=35747

(see thread: http://www.antiqueradios.com/forums/viewtopic.php?f=15&t=209410)

.

You should get one of these for each of your sets.

http://www.antiqueradios.com/forums/download/file.php?id=35747

(see thread: http://www.antiqueradios.com/forums/viewtopic.php?f=15&t=209410)

.

That's just a rebadged Sola CVT, and it can't supply the necessary current to a 21-CT-55 anyway. The Colorvolt came out in the late 60s and was limited to about 3 amperes, so about 350 volt-amperes of apparent power.

A CT-100 draws just a hair under 500, I think the 21-CT-55 is about 540 or so. A CTC-4 draws 375 watts, the CTC-7 and 9 chassis are in the vicinity of 360 watts. A nice thought, but not really practical for any 50s roundie. A nice 750 VA or 1k VA unit is superior.

You should get one of these for each of your sets.

http://www.antiqueradios.com/forums/download/file.php?id=35747

(see thread: http://www.antiqueradios.com/forums/viewtopic.php?f=15&t=209410)

.

I sort of do....I don't have that exact model that turns it's self on and off, but I've got 4 outboard CVT/VRT units (2 250VA units, a 500 and the HEAVY 1KVA unit), and I've been using my VRTs with remote switched outlets...So in the end the function is similar only I don't have to get up to turn it on and off. :D

Not sure what troubles you had, but this is my Merrill after total inductor replacement with the new ones from the list I put together. Looked pretty good to me.

http://miniman82.mysite.com/images/CT-100/IMGP5210.JPG

Crappy picture and there’s a hint of a drive line, but the color was stunning.

:rockon: