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-   -   21-CT-55 has a new home (http://www.videokarma.org/showthread.php?t=251006)

miniman82 05-01-2011 09:43 PM

21-CT-55 has a new home
 
1 Attachment(s)
CTC-2B serial B8801632 followed me home from the convention in Hilliard. :thmbsp:

Aussie Bloke 05-01-2011 10:18 PM

Congratulations mate!!!! :D

magnasonic66 05-02-2011 07:15 AM

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

Sandy G 05-02-2011 07:48 AM

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

ggregg 05-02-2011 07:38 PM

Nice!!!

miniman82 05-02-2011 10:20 PM

3 Attachment(s)
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.

John Folsom 05-02-2011 10:26 PM

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.

miniman82 05-03-2011 12:18 AM

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.

Tomcomm 05-03-2011 01:27 PM

Yet Another 21CT55
 
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

miniman82 05-03-2011 02:59 PM

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%.

sampson159 05-03-2011 03:25 PM

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

Sandy G 05-03-2011 03:53 PM

Quote:

Originally Posted by sampson159 (Post 3002312)
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...

miniman82 05-03-2011 04:00 PM

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.

tubesrule 05-03-2011 05:22 PM

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

stromberg6 05-03-2011 06:09 PM

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

Steve D. 05-03-2011 07:02 PM

Quote:

Originally Posted by miniman82 (Post 3002316)
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.

miniman82 05-03-2011 07:48 PM

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.

Steve K 05-03-2011 09:10 PM

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

miniman82 05-03-2011 10:07 PM

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

ceebee23 05-03-2011 10:18 PM

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

zenithfan1 05-04-2011 11:02 AM

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

miniman82 05-04-2011 04:23 PM

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

Electronic M 05-04-2011 04:33 PM

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.

zenithfan1 05-04-2011 06:19 PM

Quote:

Originally Posted by miniman82 (Post 3002400)
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:)

Phil Nelson 05-04-2011 07:06 PM

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

miniman82 05-04-2011 08:10 PM

Quote:

Originally Posted by zenithfan1 (Post 3002404)
unless, it's to me of course :D :deal:



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

old_tv_nut 05-05-2011 11:08 AM

Quote:

Originally Posted by miniman82 (Post 3002316)
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.

John Folsom 05-05-2011 11:15 AM

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

miniman82 05-05-2011 11:29 AM

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.

sampson159 05-05-2011 01:14 PM

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.

stromberg6 05-05-2011 03:50 PM

Quote:

Originally Posted by miniman82 (Post 3002451)
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

ohohyodafarted 05-05-2011 08:14 PM

Quote:

Originally Posted by miniman82 (Post 3002451)
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

miniman82 05-05-2011 09:29 PM

Quote:

Originally Posted by ohohyodafarted (Post 3002488)
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.

Quote:

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.


Quote:

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:

old_tv_nut 05-05-2011 09:57 PM

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.

Electronic M 05-05-2011 10:09 PM

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.

miniman82 05-05-2011 10:31 PM

Quote:

Originally Posted by old_tv_nut (Post 3002502)
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.

bgadow 05-05-2011 10:51 PM

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.

miniman82 05-05-2011 11:33 PM

Quote:

Originally Posted by bgadow (Post 3002515)
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?'

ohohyodafarted 05-06-2011 07:52 AM

Quote:

Originally Posted by miniman82 (Post 3002509)
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

jeyurkon 05-06-2011 09:11 AM

Quote:

Originally Posted by ohohyodafarted (Post 3002532)
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 which measures the actual intensity vs wavelength rather than giving you RBG values like a colorimeter does.

John


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