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Old 02-10-2011, 03:41 PM
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RCA Model 1 Converter Prototype

I never cease to be amazed at what pops out of the wood work. ETF just posted color photos of an RCA model 1 converter prototype chassis.
http://www.earlytelevision.org/whatsnew.html
In the B/W photo two chassis are shown in the cabinet, which seems to be more the complete television of the era. In the color photos the chassis has no power transformer and the H/V section lacks a ventilated cage. This appears to be more a converter used with an existing set. Might anyone have an idea as to the differences?

Phil
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Old 02-10-2011, 08:22 PM
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Notice that we've changed in page. At first I thought it was a converter, but it has a tuner. I know it is an early color prototype, but I'm not sure which one yet.

There is a separate power supply chassis which is missing.
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Old 02-10-2011, 08:42 PM
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Give ya a buck-fitty fer it...Looks like sumpin neat fer my Young'uns t'play with...
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Old 02-10-2011, 10:12 PM
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Thanks.
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Old 02-10-2011, 10:59 PM
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Tell us more Steve! Where did this come from? We are dying to know the entire story

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Old 02-10-2011, 11:14 PM
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I see Harry Poster's name at the bottom of the page. I believe his collection consists of obscure early color sets, so a model 1 would be at home in his collection.
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Old 02-11-2011, 12:48 AM
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I NEED NOTHING but Help !

5 dolllars U.S. ?
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Old 02-11-2011, 04:02 PM
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Info needed on the early RCA color prototypes

Hello all..

Does anyone have a tube layout, or even a tube list, for the main chassis of the Model 1, 2, etc?

Although this chassis has the same 4 in-line knobs as the Model 1 shown in the RCA filings, the tuner and CRT number indicate it's probably 1951-1953...a tube layout of known models would make it easier to decide exactly what it is, and where it fits into the RCA pre-production line up.

Any help would be appreciated, either via Private Message, or post in this thread.

Thank you! Harry
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Old 02-11-2011, 04:17 PM
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Looking at the date codes on the tubes would likely narrow it down; the service life of these prototypes was probably never longer than a number of months since the color standard was still evolving.
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Old 02-11-2011, 05:29 PM
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Color picture #5 clearly shows one each GE and Tung-Sol branded tube. Makes one wonder how many hours were put on the thing. Phil
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Old 02-11-2011, 08:08 PM
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That is a really interesting set, it doesn't seem to really match any of the ones shown in the pictures.
The first one seems to be a 630 based chassis with some extra chassis's added, they get further away from that as they go down, pictures 2 and 3 look the closest not having a power transformer mounted on the same chassis as the tube.

You have to wonder how many more working CT-100's would be around if they had stuck to using the existing 16" metal B&W tube shells?
They were much more dependable at holding vacuum than the 15GP22.
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Old 02-12-2011, 11:45 AM
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Quote:
You have to wonder how many more working CT-100's would be around if they had stuck to using the existing 16" metal B&W tube shells?
They were much more dependable at holding vacuum than the 15GP22.
I dont think it would have helped. Because all color crt's have to be made in two peices (a front and rear section) so as to allow the placement of phosphor dots and instalation of the shadow mask. Even the early metal prototypes were made in two pieces as can be seen in this photo.

http://www.earlytelevision.org/rca_developmental.html

You will note the rib just rearward of the front lip of the tube. That rib is where the front and rear sections were welded together. This tube suffers from the same leaking weld issues as the 15gp22 and the 21axp22.

Initially we thought the leaks were in the glass to metal bonds, but we have since re-thought the problem and have discovered through using a helium leak detector that it appears the leaks are most often in the weld. That is why we see so many good B&W metal tubes. B&W tubes have no weld, just glass to metal bonds which work very well. Making consistant, vacuum tight welds, is a very hard thing to do when working on light guage metal such as used in these crt's.
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Old 02-12-2011, 01:05 PM
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Quote:
Originally Posted by ohohyodafarted View Post
Initially we thought the leaks were in the glass to metal bonds, but we have since re-thought the problem and have discovered through using a helium leak detector that it appears the leaks are most often in the weld.
But even with that in mind, the elimination of 4 possible failure points, might have improved the probability of survival of these CRTs. 21AXP22s seem to have survived better than 15GP22s... I suspect that RCA had good reasons to revert to the earlier construction methods for the 22AXP22.
Too bad frit for CRT application was not invented earlier!
jr
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Old 02-15-2011, 01:22 AM
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Old 02-15-2011, 01:24 AM
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A leak is a leak is a leak!!!

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