EARLY COLOR TV
The First Year
June 2000 to June 2001
devoted to anything related to vintage color TV.
> A 15GP22 tricolor kinescope has its control grids driven by what is essentially an RGB video signal. When the CT-100 was designed, compromises in the NTSC standards resulted in artifacts on the screen due to overlaping regions in the luminance and chrominance spectrum. This forced CT-100 and other designers to limit the bandwidth of the red, blue, and green video amplifiers in NTSC receivers to only 3-MHz or so. It results in a loss in luminance resolution compared to that permitted by the 4.2 MHz high-end limit defined by NTSC standards. It would be another twenty-five years before the development of comb filters allowed the full lumnance signal to be reproduced on the screens of modern NTSC receivers.
> Bruce has a 1954 Admiral model 38A1A in his collection. One of his challenges was to locate a schematic, which he ultimately did through the web. It's the basis of this presumptive (?) e-mail exchange Bruce had with a collector of vintage radios…
At 10:45 PM 6/3/00 +0000, you [Wayne] wrote [to Bruce]:
I just found your posting through a search I was making for my own Admiral TV project and was wondering if you found any sites or had any luck with your schematic search? I have no help for you, as I am into antique radios but I picked up this set (couldn't pass it by) and now need a schematic. Thanks in advance for any help you may be able to give!
To which Bruce replied:
From: Bruce B.
To: Wayne F.
Sent: Tuesday, June 06, 2000 11:38
Subject: Re: Admiral 38A1A
Wayne I have a 38A1A schematic. Is your set a 38A1A? I also have a bunch of info on these sets. Can you call me?
Then "it" happened.
From: "Wayne F."
To: "Bruce B."
Subject: Re: Admiral 38A1A
Date: Tue, 6 Jun 2000 18:28:46 -0000
X-Mailer: Microsoft Outlook Express 5.00.2….
Thanks for writing Bruce, but I was moving the TV and dropped it down the stairs (you know how heavy these ones are) and totally destroyed it. I am crushed as it was in very good condition (except one knob) and didn't deserve such a fate. I managed to save the emblem and tuning knobs and a few internal pieces but that is all.
Count 'em. Twenty pins. You're looking into the vacuum end of a 15GP22 stem manufactured years ago when there was still a small market for rebuilt 15GP22 tricolor kinescopes. Look for this sample to be the one used to prove our process to resuscitate these ancient bottles.
> Pete: While checking the links at Merrill Mabbs' web site I spotted the magic nomenclature: CT-100. As I am one of the VERY lucky few to posess a copy of this technological masterpiece, and after reading most of the great information on your site, I am compelled to write. First a little story about how I came to be the "caretaker" of #827 [This link updated 7 April 2002] .
After my military service, I took a job with a local electronic distributer in CT. This allowed me to meet many of the TV repair technicians in the greater Hartford area, including the guys from the local RCA factory service facility. Long a color tv "nut", and having read many color schematics, articles, and service literature, I was overtaken by an almost obsessive desire to own a CT-100. This desire was made known to all who came in to purchase parts, etc.
About a year passed, when one afternoon, at work, I received a call from my buddies at RCA service informing me that, while cleaning the storage area of thier shop, they found a CT-100, and if I wanted it, I better get over there FAST, or else it would be JUNKED that afternoon! I immediatly informed the boss about what I was going to do; he wasn't thrilled, but he understood, I think. Instead of a '62 T-Bird, my CT-100 hung over the trunk lip of a beloved and missed '66 Buick Wildcat (one helluva car). I got it home and up to my second floor apartment. I think the neighbors thought I was (am) nuts.
My SET was in relativly good condition, as it had been repaired before being stashed in the store room; the customer decided not to pay the bill, and from what I understand, bought a new TV instead. This was in 1974, so most of the components were just fine. I replaced only the components that were either obviously no good, such as physically leaking capacitors, and some high voltage insulation in the cage, and also the tube socket under the 6CL6 last IF amp. over the years it had become burned to the point of disintegration. After checking all tubes(except the 15G), I connected an antenna and powered up #827. I was rewarded by one of the most out of convergence pictures I have ever seen. Also, the "Q" signal was absent, but it worked! Replacement of a 6AN8 cured the "Q" problem, and I had a full color picture on that wonderful, flat screen.In 1978 we moved to a house with enough room for a collection of vintage electronic goodies, and #827 was the focal point. I enjoyed demonstrating it to anyone who would put up with my spiel, but limited the number of hours of "on time", with an eye toward longevity. My precaution was for nought, however, for one evening, while enjoying some program, the focus filter cap (0.006 uF @ 6 kV, paper) decided to short, and take the CRT with it!
After the diagnosis, and a few tears, I buttoned up old #827 and stashed it in a basement corner. I do have a few screen photos to look at, but it just ain't the same. A couple of weeks ago, I pulled it out of the corner with the idea of donating it to the Vintage Communications Museum of CT, but after reading of the possibility of rebuilding the 15GP22, I will hold off until I have more info on the subject.
I want to express my sincere thanks to you for building your web site, and filling it with a wealth of information about a subject that is dear to my psyche. If I can be of any help to in your "labor of love/insanity", please let me know!
Kevin G., Connecticut
> The 15GP22 was the first commercial tricolor kinescope manufactured for use in NTSC receivers.
>Filaments: 6.3 Vac. 1.8A. Pins 1, 20.
>Cathodes: 125 Vdc. Pins 2, 7, 19 (RGB).
>Control grids: 20 to 100 Vdc. Pins 3, 8, 18 (RGB).
>Accelerating electrodes: 240 to 375 Vdc. Pins 4, 9, 17 (RGB).
>Focus electrodes: 3 to 5 kV @ about 100 uA with an approximately 250-volt correction waveform added. Pin 6.
>Convergence electrode: 10 to 12.5 kV w/dynamic convergence waveform added. Pin 13.
>Second anode: 19.5 kV @ about 3/4 mA
>Deflection angle: 45 degrees
>A purity coil is placed over the neck and is the item closest to the socket. It is supplied with current from the low-voltage power supply and is adjustable from its maximum down to near-zero.
>Chroma and luminance are not applied separately to the tube. RGB is applied to the control grids.
> Of the vintage color sets that use the 15GP22, we have two in our group who own the Westinghouse model H840ck15. This set is important because, as the quote from Rob's info exchange page indicates, the actual race to retailers was won by Westinghouse...
"I am the proud owner of a Westinghouse H-840CK15 (s/n 275) , that 'disaster deviant that weighs half a ton' as Gary described it in his post of 10/31/99. According to "Tube - The Invention of Television" at the bottom of page 327, RCA's CT-100 was preceded early in '54 by Westinghouse, who beat RCA to the punch and got their set into stores first."
Wed, 14 Jun 2000 19:09:24 EDT
I found your web site on the CT-100. I'm glad to see that some are still working and I wish you luck on the CRT. I remember working on one when I was a teenager in the early 70's. One thing I did do at the TV shop was I saved a lot of Zenith's early color sets they were trade-ins at the time. The best part is I saved a lot of CRT's and parts.
I work at a Headend for Comcast Cablevision and we have one of the sets in our Digital Headend in Orange County CA. Zenith made it in 1960 one of their first it even has a tube remote receiver. It sat for 20 years at my parents house till it was moved to the Headend a few years ago. After a few problems with IF and High voltage and a new CRT "21FJP22A" and some small stuff. It has been in almost every day service. I would say we have run it at least 5000 hours since it was repaired. The picture is almost as good as a current Sony just a little less sharp and less contrast. We have only had to change a damper tube and power supply tubes. It might help that it sits on a raised floor that is very cold from the AC used to keep the equipment in the room cool.
I have a mint set at home also a 1960 I only run it a few times a year maybe 10 hours total just to keep it in shape. I wish I saved the CTC2 I had but at the time I was into Zenith and had a lot of trouble with RCA's pc boards oh well.
A lot of people get a bang out of the set and can't believe how old it is and how well it works The round CRT helps. Good luck again on your set and the CRT I will be checking back to see your luck.
On your set about the UHF most sets made before 1963 did not have UHF tuning. It was an add on like AC in cars. In 1964 the FCC said all sets had to have UHF. That was how we could tell on the spot if a set was older then 1964
> Here's something I picked up somewhere about NTSC interlaced scanning and vertical resolution.
Broadcasters must reduce the level of vertical detail in the pictures they broadcast to prevent small area flicker on interlaced displays. An interlaced delivery system has only 1/2 the dynamic resolution in the vertical axis. Dynamic resolution is what happens to the delivered resolution when objects are moving. To eliminate artifacts as objects move in the vertical direction, the vertical resolution must be limited to 1/2 that available for any given number of lines. On the other hand, a progressive scan system can deliver almost twice the level of vertical dynamic resolution for the same number of lines, without producing artifacts.
> Just thought I'd finally write to tell you that I have a CT-100, too. And also a NIB 15GP22! (No, don't ask -- it is not for sale.) This is actually my second CT-100.
(1) The first was brought up to the Vancouver, BC area, where I live, by an astronomer/physicist who was (is?) teaching at Simon Fraser University. I found out that he had an old TV set (didn't know that it was a CT-100 at first) and went to visit him. He eyed me carefully and said that he couldn't keep it any more, and was looking for someone suitable who would give it a good home. We took it back to my house that evening in his van. He had obtained it in the early 60s when he lived in Berkeley, CA, as did I at that time! He and his wife used to watch it in their small bedroom, where it took most of the free space.
When I examined it, I found a few broken tubes and a blown fuse. When I replaced those and fired it up, I heard the HV come on, but the screen would not light up. When I looked inside the tube from the neck end I could see lightning-like discharges inside. The tube had leaked air. Such a tube can't be rebuilt, I'm sure. [We need to have a friendly bet on this one. --Pete] The phosphors would have degraded severely from the oxygen. And the leak could be along those two long glass-to-metal seals on each side of the convergence electrode. [You can read Alan's response to my querry about rotting phosphor on his info exchange page.]
(2) An opportunity came to obtain a second set a few years later. It was in the possession of a former Philips technician, who said that Philips had bought the set and a spare CRT for training purposes. He said that when he had last tried it, it had worked, but the vertical height was too small. After some time I got these pieces from him. When I plugged in this set there was a bright white flame at the rear apron of the chassis. I have not attempted repair (I was a TV service technician since about 1955, when I was still in high-school). I sold the first set to finance the purchase of the second, and it went through several hands before coming to rest in a museum near here.
I had a spare used 20 pin socket, and that has been wired to make a testing adaptor to use with regular CRT testers. (For emission testing I don't think that extra convergence electrode will make any difference.) But I haven't tested the 15GP22 in the set, or the "new" one. The "new" tube, in the original box, does not appear to have been installed--judging by the lack of marks on the aquadag coating. I also have original RCA data sheets for thr 15GP22, dated March 1, 1954, except for the "Typical Drive Characteristics" page, which is dated Sept. 3, 1953, and the "Typical Light-Output Characteristics" page, which is dated Jan. 13, 1954. If you will send me your snail mail address I'll be happy to send photocopies of these pages to you. [Accomplished. Thanks Alan. The base diagram of the 15GP22 appearing in the theory page for the 15GP22 is from that contribution.] Good luck with your project!
Here's an example of my bull-headed demeanor in this regard.
You will never, on this site, see the word 'televisions' used for the term television set. Nor will you ever see the word 'televisions' used for the term television sets. Thank you.
You will never, on this site, see the word 'televisions' used for the term television set. Thank you.
I really enjoyed your web page about old color TV's, something that is rare these days. I never was fortunate enough to find one like you have, or I would be right in there with the others trying to restore the thing.
When I first was married in 1965, I was able to buy a 1956 console (CTC5) with a rebuilt jug for $60. We really enjoyed that set for about five years. I sold it for $35. I bought it during the winter, but on a clear cold day I hauled it home about 10 miles in my '60 Morris Minor convertible with the top down and the set in the back seat upside down. That was quite a trip.
I know a guy who has owned 4 or 5 of the CT 100's and restored some of them. He says the CRT's became gassy over time. He brought one back to life by running the filament about 50% for a year. Something to think about. I have a friend who owns one with a bad tube, but he has no plans to restore it. I sure hope your rebuilding plans work out, because that CT-100 has just a dynamite picture when its working. Don't give up, there has to be someone able to rebuild that tube.
> Personally, I get a kick out of stuff like this, so here's a shot I set up last April...
It's what nearly fifty years of color television engineering looks like. On the right, weighing in at over sixty pounds, our famous RCA CTC2 chassis manufactured in March 1954. And on the left, weighing in at about a pound and a half, a Zenith TV-on-a-pc-board manufacured in the second week of January 2000.
This COMPLETE television set (okay, sans speakers, yoke, and 25-in. crt) is entirely a pc board (no chassis) and includes the low-voltage switching power supply, high voltage and sweep circuits, stereo decoder, infrared remote receiver, comb filter, cable-ready tuner, and everything else needed for a modern year-2000 NTSC color television set.
> "By the end of 1954, about 7,000 color television sets were in use throughout the United States." (Elmer W. Engstrom, President of RCA. Quoted from his guest editorial in the January 1965 issue of "Radio-Electronics" magazine.) He went on to say to readers of the magazine, directed, in large part, to people in the TV service industry, "Its limits for service will be only those of the imagination." Actually, as the previous tidbit suggests, electronic systems have become so reliable through the use of microcircuits that very little -- if any -- service is required during the life of a modern NTSC color television set.
> Okay, I'm getting old as fast as the next guy, but didn't it say "8" days for the ebay sale of a one-owner CT-100 on July 28, 2000?
Here's the cold fact -- a CT-100 sold for $776 in -- basically -- a day.
Jul-29-00 20:11:34 PDT
Jul-28-00 18:24:42 PDT
Jul-28-00 17:46:54 PDT
Jul-28-00 15:08:56 PDT
Jul-28-00 12:13:54 PDT
Jul-28-00 05:53:17 PDT
Jul-28-00 02:55:42 PDT
> THE_SET has amassed considerable data on the three, not four as stated on e-bay, CT-100s... most of it confidential and not for publication. However, I believe another interesting CT-100 story will emerge and quite possibly another operational Merrill since at least one of the 15GP22s is good. Late info will be posted as it becomes available.
For those in the group and others who have not had e-mail answered recently, here's my rationalization :
> In early 1954, the cover of Radio-Electronics magazine featured an "experimental" color set using a 15-inch tricolor kinescope. (UPDATE)
This tv is a mystery to all who have seen it so far. Considering lead times for magazine publishing in those years, there's little doubt that the picture was shot sometime in 1953. Click here for a higher resolution image, and if you can identify the set in any way, please let THE_SET know. Thanks to Steve for conjuring up this mystery. [Link updated April 2002; October 2008]
> Here's something from Mike's info exchange page and my restoration log about tricks the phyche can play on an overzealous restorer: it concerned my ailing 15GP22...
"1-5-00 [but posted 4-22-00] I was intrigued by your comments on the fate of your picture tube for the CT-100. Very strange that you would get a current flow but no glow from the heaters. Has the tube gone soft? Are the getters white? [ Yes and yes. I'm afraid the "heat" came more from profuse optimism and a sweaty palm than Ohm's law. --Pete ]"
> How many CT-100's are still in existence?
That's a question often asked but probably no one can answer. We simply document as many as possible and be content with that. But one thing I've learned to expect since starting this site is that another CT-100 will pop out of the proverbial woodwork in another few months.
To check our latest tally, which does not include four or five more we've "heard" about, go back one screen and click on the [CT-100: info exchange MENU] link.
Vintage Graphics = Vintage Information
>Another great source of vintage information can be vintage articles. These relate to early color picture tubes: 1 2 .
>Here's a CT-100 co-op ad that appeared in the "Los Angles Times" one spring day in May 1954. [click here]
>This CT-100 display ad appeared in the same month; it was on page 17 .
> Click here for an extraordinary report!
> We get to peek into a public relations package, part of a sales campaign developed by RCA to launch its CT-100. Not only did they have to create a buying frenzy in the ultimate customer, John Q. Public, the dealers had to be hyped...
> This graphic raises a question about how well the current P22 phosphor standard supports the 1953 NTSC standard. (Update)
> INVENT -- To produce or contrive (something previously unknown) by the use of ingenuity or imagination.
> This is what it's all about... click here .
> Hi Pete,
Just discovered your restoration site and must let you know of one more CT-100. I have just recently been contemplating the task of getting it going again. In fact, it was my search for some 6AN8s that lead me to your site.
My first exposure to the CT-100 was in the '50s while working in a TV shop in New Jersey. We had one demo set. But of course, no one could afford it. In the early '60s, while looking for a cheap black and white set to add to our "new" Seattle apartment, I ran across the set in a small shop. Out of curiosity I asked what one of those things was worth now. The guy replied "I'd sell that damn thing for $50." It worked in black and white (that's all that was being broadcast) so I figured the picture tube was OK and I gave him the $50; then had to carry it (with help) up to our 3rd floor apartment. It served as our family TV for the next 10 years or so.
I've hauled it around to several subsequent homes, but it hasn't run in many years. I don't want to move it many more times and am considering giving it to a museum. I thought I might see if I could get it to work first. To that end, I plugged it in the other day and to my amazement the audio came up fine and there was no smoke, but there was, however, no video.
It looks as though your site could be a great help if I really do get to work and try to make it go again. Any comments or suggestions would be greatly appreciated. Thanks for what you have done already.
[Perhaps there's a significant cluster of CT-100's in the Seattle area. These e-mails were received in early January 2001. The three sets are represented on the Living CT-100 list. One other CT-100 is known to be in the Seattle area. -- Pete][Later, in a 11 Jan 2001 e-mail, Jim confirmed a weak raster but no video on his CT-100 serial number 788.]
I found your site tonight when I was rambling around the web. Good to know that others out there are bringing these back to life.
I have two CT-100's that are awaiting restoration. I rescued these from the estate of a TV repairman about 15 years ago, but unfortunately, they were not treated to the best of conditions. One has a broken neck on the picture tube, and both are missing the door on the front. I don't know the condition of the other picture tube. I would be interested in your tube rebuilding process when it becomes available. The history I got from the previous owner was that our local TV station in Seattle originally used these sets when color broadcasts started.
I am an engineer in the biotech industry, but I worked my way through high school fixing TV's so I have a fondness for these old beasts. I will try to get around to the back of them in the next few weeks and get the serial numbers to add to your list.
> First Quarter 1954
Fortune magazine forecasts 10+ million color sets in five years.
Westinghouse first to market a color set; RCA quickly follows with its famous CT-100.
RCA gets first "official" order for unspecified number of sets.
"Set Buying Lags" exclaims newspaper.
Westinghouse sells perhaps 30... thirty!... sets.
RCA slashes the CT-100 to $495; offers rebates to owners of black and white sets.
"...about 7,000 color television sets in use." (President of RCA, Elmer W. Engstrom, 1965)
It wasn't until eight years later that the New York Times reported a million color sets in use.
Forty-seven years later, Pete wonders how many color sets were actually made in 1954... according to what apparently amounts to folklore, Westinghouse produced 500 and RCA produced 5000.
More to come...
In April 2001, the following sales information was provided by Alexander B. Magoun, Director, David Sarnoff Library, Princeton, NJ. "...Thomson/RCA's History Center in Indianapolis some years ago indicates that RCA built 4,600 CTC-100s[sic] at its Bloomington, IN, plant in 1954, and sold 4,300 of them." Note: This Tidbit was updated on June 3, 2001.
> 2 February 2001 Am pleased to have received this CT-100 story from Craig. If you missed the link to Craig's operational CT-100, click here .
Hi Pete! Steve D. said you were interested in hearing my story about my search for a CT-100 in working condition. I would be happy to share it with the readers of your website, which I think is terrific!
I just crawled behind my CT-100, and the serial number of my set is 108.
I was born just as they must have been gearing up for the production run of CT-100's. Later, when I was 8-years old, my parents, my sister, and I were invited to a neighbors to watch "The Wizard of OZ" on their CT-100. I will never forget how astonishing and wonderful that was.
I was hooked. The NBC peacock bursting into glorious color on a CT-100 is a thrill. I took books out of the library on color television technology when I was in junior high school to try and understand this marvel. My first job was in the mid-70's at KTTC-TV, an NBC affiliate in Rochester Minnesota; they were still using those gigantic TK-41 color cameras with the huge zoom lens and the three large image tubes.
In the early 1990's, I began looking for a CT-100 in working condition. It took many years, but I found one through the connections of a retired TV repairman in Cincinnati who was a radio and TV collector with an antiques and collectibles store. The owner of the CT-100 was in Seattle and had restored it by replacing the capacitors and dead tubes. He sent me photographs of it working and it looked beautiful.
I had it crated by one of those Mailbox stores. The best way to ship, I was told, was by train. It would be picked up by a truck, taken to the train, loaded and transported. Then, in Cincinnati, it would be unloaded onto another truck and driven to my home.
I was worried sick, not only because of all the transferring, but because it could not be insured properly; and it had to be listed as "auto parts," or something like that, or the freight company would not even touch it. Transport took six days; the call from the freight delivery company came. It was delivered in a truck too large to back into my driveway. I had to help roll it on a dolly to my front door and they left it, still crated, in the middle of my living room.
I carefully uncrated and unwrapped it, holding my breath. Not a scratch... but it might have been dropped or bumped... and those filaments in that forty year old picture tube.... I examined it carefully... took the back off. All the tubes were firmly in place. I put the back on, hooked up the antenna, plugged the set in.
The dial light came on, I was certain I could smell ozone pouring out the back, the sound came up, then the picture tube came to life... a minor adjustment to the fine tuning and COLOR TV!
I still turn it on a few times a year. It still works, but the tint control is mechanically broken, so I must replace it.
> Great CT-100 stories are being received from all over. This one comes with a new twist from a Canadian devotee of tv technology.
I was delighted to come across your CT-100 web site. I've always been fascinated by TV technology.
My brother and I built our first TV set as teenagers in the 1950s and powered it with a homebuilt 110-Vac generator on our parents farm (since we had no commercial electric power). Anyway, here's my CT-100 story.
In 1965 when I was a young electrical engineer just out of university, a telecom salesman from N.V. Philips in Toronto would occasionally admit me to the Philips employees store where they sold surplus and damaged electronics stuff to their staff. Color sets were well out of my financial capability in those days, so when I noticed an old color MONITOR in the back of the store, I decided to buy it not knowing if the CRT or any other part of it was any good.
It turned out to be a chassis that had been commercially converted to a studio monitor by an outfit in, as I recall, New Jersey. I paid $70 for it with the idea of converting it BACK TO a color television receiver.
The tuner, IF strip, and power supply had been removed (or maybe purchased from RCA less those parts... this set wasn't built from scratch). It was mounted in a steel cabinet with all the controls brought to the front panel. The chassis and everything else is intact and the same as the CT-100.
In a burst of youthful enthusiasm, I located a surplus '60s Zenith "Golden Grid" tuner, and because I could buy Zenith IF coils and traps locally, I decided to replicate a Zenith IF strip and sound demodulator. (By the way, the published bandpass characteristics of the 7-stage CT-100 IF were the best I've ever seen in a tube set... about as close to theoretical as you can get.)
I built the power supply using two transformers from junked B&W TV sets. The Philips engineers had been experimenting on the chroma circuits, so I had to restore all circuitry back to original. It also had an add-on "aperature correcting" circuit, which I removed because it greatly emphasized the "snow" from weak off-air signals.
My references included Sams' "Color TV Training Manual" TVC-1 (1956) and the book "Color Television Fundamentals" by Kiver (1964). The Sams book was ideal for my purposes because it describes in detail every CT-100 circuit function. Someone also gave me a full CT-100 schematic.
To align the set, I hiked myself over to the local Heathkit store and bought a VTVM, color bar/convergence generator, and a sweep/marker generator. After about six months of work on my kitchen table (yes, I was single then) the whole arrangement worked! It was a magic moment. I still remember the thrill of seeing that first color picture. As I recall it, the picture detail was quite good and the brightness was adequate although not up to todays standards.
I still have this old set, but will have to sell it someday since no one I know is even remotely interested. I dont know how much "on" time it incurred as a monitor, but the 15GP22 was still good the last time it was fired up in 1970 or so.
EMAIL 2 [02-12-01]
You are probably correct, that my monitor was made by RCA, nevertheless, when I bought it there was no RCA name anywhere on it. There was another name on the front access door, but unfortunatly I misplaced it years ago. That name led me to speculate that the monitor was re-packaged by some other company.
In 1948, the Rauland Corporation sold its cathode ray tube manufacturing operation to Zenith Radio Corporation. By 1953, the race to color was proceeding at a gallop pace, and perhaps Zenith-owned Rauland facilities were tasked with producing tricolor picture tubes for Zenith's developmental efforts. Maybe.
We know that RCA provided developmental tricolor kinescopes, the C-73599, to rivals Westinghouse and CBS. We further know that RCA delighted in holding patients on a popular product to reap the licensing revenue. We know that RCA promoted a kit of critical parts for the compatible color television receiver it developed -- vertical convergence transformer, purity coil, and 45-degree deflection yoke, to name a few. We know that CBS not only used RCA C-73599s to develop 15-inch compatible color sets, it actually manufactured its own enhanced version, the 15HP22, which had NO internal decorative mask.
And finally, the way the tube business works TODAY has one manufacturer buying sample glass and parts from another to build prototypes. Certainly, evidence suggests it was done the same way in 1953. Photos of the "Rauland" 15GP22 "counterfeit" look so much like the C-73599 (check the decorative mask) that one can wonder if it was constructed primarily from Rauland parts, RCA parts, or maybe even CBS parts. Heck, it may even have been built in Camden, Harrison, or Lancaster.
As always, opposing points of view, new information , or anything else of interest is always welcome. --Pete
Thanks to Steve and Jeff for their information. As further data of interest accumulates, it will be posted. And be sure to check Steve's site, particularly for the latest in preWW2 television restoration progress. [www.earlytelevision.org]
This "Zenith" 15GP22 will be installed and tested in a Dage Model 650A studio monitor Steve is restoring. You can follow the restoration saga on Steve's information exchange page, beginning with the February 7, 2001 entry. Click here , jump directly there.
> If you are an aficionado of vintage color television, you've heard about an ill-fated attempt to broadcast color in 1951 -- three years before the current NTSC system took hold. Here's Pete's slanton the Color Wars.
> A bit out of context perhaps, but a nevertheless interesting first-hand story about 1951 CBS color compatibility . Note: This link was updated on June 3, 2001. --Pete
> Thanks to Sandy Geiger for another interesting CT-100 story. It's the first I've received describing a CT-100 for sale by a shop.
Hello. In 1975, I was a high-school senior at McCallie School, a boarding school in Chattanooga, TN. Right on the other side of the Missionary Ridge tunnels, there was a "Bohemian" area of Chattanooga known as Brainerd, which had a TV/radio repair shop. We had to walk right by this place, and from time to time, he'd get in some neat stuff. One day he had an RCA CT-100 set for sale for $150, that looked brand-new, out of the box. Looked just like your Merrill, great big mahogany cabinet, little-bitty CRT. Wanted it real bad, but $150 was more money than I had, and besides, there are more ways to spend one's money when one is 18 -- beer, gas, girls, beer, etc. Too bad, because that set looked like a good one.
Good luck on your restoration -- too many artifacts of our technological history are lost -- and to me that's really a shame. Would like to SOMEDAY have my own CT-100.
> It's hard to believe nowadays when 24/7 programming is the norm, but I recall when WFIL channel 6 in Philadelphia, the ABC affiliate, would actually have hours of dead air time Saturday afternoons.
> If you, like me, enjoy technical and engineering television books from the '40s and '50s, you will often find WFIL, WCBS , and WPTZ (NBC in Philadelphia) test patterns photographed and used as examples.