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  #1  
Old 11-14-2017, 07:25 PM
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Question about 15GP22 production

Does anyone have concrete information as to when exactly commercial production of the 15GP22 began, and when it ended?

I know the developmental tubes in the Model 5s were built starting in November of 1953. I'm assuming commercial production of the 15GP22 started in late December 1953 or early January of 1954, and probably lasted maybe six-ish months at most? And about when was hand welding of the ultor flange abandon in favour of automated welding?

My good 15GP22 was manufactured the 13th week of 1954; I'm trying to determine if this tube was hand or machine welded.
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Old 11-14-2017, 08:16 PM
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Answer: both, not that it matters.

Even a ‘machine’ weld in those days was still a manually controlled TIG weld, and any holes found by the leak detector would have to be fixed by hand.
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Old 11-15-2017, 10:43 AM
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Quote:
Originally Posted by miniman82 View Post
Answer: both, not that it matters.

Even a ‘machine’ weld in those days was still a manually controlled TIG weld, and any holes found by the leak detector would have to be fixed by hand.
Thanks Nick. Bob mentioned to me that the later 15Gs seem to have a lower leak rate in his opinion.

Does anyone know when production started and stopped? I'm more interested in knowing how long the tube was actually built.
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Old 11-15-2017, 11:17 AM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by benman94 View Post
Thanks Nick. Bob mentioned to me that the later 15Gs seem to have a lower leak rate in his opinion.

Does anyone know when production started and stopped? I'm more interested in knowing how long the tube was actually built.
My 1964 Allied still listed a 15GP22 for $222.00. IDK, if it was NOS or recently manufactured.
The newest type listed was a 21FBP22.
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  #5  
Old 11-18-2017, 10:44 PM
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Pete Deksnis Pete Deksnis is offline
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Ben, the oldest 15GP22 I know of has a date code for the fourth week of 1954.

Pete
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Old 11-18-2017, 11:05 PM
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Quote:
Originally Posted by Pete Deksnis View Post
Ben, the oldest 15GP22 I know of has a date code for the fourth week of 1954.

Pete
That's a bit younger than I was expecting. Thanks Pete.

It kind of pokes a hole in the hypothesis that the Admiral set was the first commercially available color set: Admiral would not have been selling sets with prototype jugs to the public, and if the oldest known production 15GP22 is from the fourth week of 1954, then nobody could have commercially released a set before then. You've gotta have CRTs to put in 'em...
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Old 11-19-2017, 12:53 PM
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Pete Deksnis Pete Deksnis is offline
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Quote:
Originally Posted by benman94 View Post
Does anyone have concrete information as to when exactly commercial production of the 15GP22 began, and when it ended?
Maybe this is the back-end of the puzzle. Link to the graphic on my site of the only 15GP22 date code I know of that is not from 1954; it is from 1959 (in case the link doesn't work).

http://www.earlytelevision.org/Deksn...926-15GP22.jpg

Pete
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Old 11-19-2017, 01:00 PM
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Quote:
Originally Posted by Pete Deksnis View Post
Maybe this is the back-end of the puzzle. Link to the graphic on my site of the only 15GP22 date code I know of that is not from 1954; it is from 1959 (in case the link doesn't work).

http://www.earlytelevision.org/Deksn...926-15GP22.jpg

Pete
Makes one wonder if it was a rebuild, or if the 15GP22 was still being manufactured new?

I figure RCA had built four or five thousand CT-100s, then there were the other 15 inchers (at least 500 Westinghouse sets, 100-200 GEs, etc) and finally all the studio monitors. There would have been some demand for 15GP22s into at least the 1960s. Probably not that great of one, but a real demand nonetheless.
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Old 11-19-2017, 01:17 PM
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Quote:
Originally Posted by benman94 View Post
Makes one wonder if it was a rebuild, or if the 15GP22 was still being manufactured new?
My feeling always was that it was new. Or, perhaps assembled from a pile of parts held in storage for years...?
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Old 11-19-2017, 01:23 PM
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Quote:
Originally Posted by Pete Deksnis View Post
My feeling always was that it was new. Or, perhaps assembled from a pile of parts held in storage for years...?
I think there are two plausible explanations:

The datecode is a misprint and it should be 1954, or the tube was manufactured new in 1959. The 15GP22 is on price sheets well into the late 1960s and early 1970s. Warehousing a bunch of product is expensive. It's possible that RCA kepts parts around to "build" new 15GP22s on demand for a while. They wouldn't be the first company to do something like that...

If it was a rebuild you'd expect to see a label saying that the envelope was reused and the tube was rebuild. I've seen an RCA rebuilt 15G with such a label, and I've never seen a rebuilt tube without a label clearly identifying it as such.

I think your gut feeling is right Pete.
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Old 11-19-2017, 02:39 PM
Olorin67 Olorin67 is offline
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i suspect they may have kept in production a while for studio montor use.. since 21" tubes might be a little big for that purpose. Were there any other smaller tubes available for when a 21" might be too bulky?
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Old 11-19-2017, 07:19 PM
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Just my opinion. The whole 15GP22 production was so crude with the flat plate, early phosphoring, physical alignment, welds, glass to metal, etc., It had to be low production and the 21 series blew that out of the water to the bean counters. I cannot imagine RCA kept that assembly line around for long. As for studio monitors it was a quick jump to jeeped up 21CT55 sets as many photos document. I think the ones on Allied, etc. were happily gassing away in loneliness on the shelves.
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Old 11-19-2017, 08:53 PM
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On application of the 15G that lasted a LONG time was color film viewing machines (I forget the correct name) used for doing color correction/editing of films.

I remember a page on one of the big CT-100 sites many years ago told of how a few years before a collector contacted the company that maintained these machines, the company had given up servicing the 15G equipped machines and tossed 6 NOS 15Gs in the dumpster.
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  #14  
Old 11-19-2017, 09:41 PM
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Quote:
Originally Posted by Electronic M View Post
On application of the 15G that lasted a LONG time was color film viewing machines (I forget the correct name) used for doing color correction/editing of films.

I remember a page on one of the big CT-100 sites many years ago told of how a few years before a collector contacted the company that maintained these machines, the company had given up servicing the 15G equipped machines and tossed 6 NOS 15Gs in the dumpster.
(1) the last machine using a 15GP22 operated until around 1975 in Mexico.
(2) Your remembrance is on my CT-100 site; here's my painful posting: What's the chance that serendipity will rescue a pallet of 15GP22s from a dusty warehouse somewhere? I've always believed it would. This next email shows it can happen and hopefully will.

"Date: Sat, 03 Nov 2001 14:16:55 -0800
Pete,
I am sick. I had no idea that anyone was interested in these old tubes.
I make color film analyzers and had the old stock from Hazeltine when
they discontinued production. There were six of those old 15 inch CRT's,
but since there were no more analyzers in the world using the tubes, we
chucked them to make room.
Regards,
Ric "

(6 Nov 01 update: Just missed these by a couple of years! The six 15GP22's had their vacuum broken, then were sent to a Los Angeles landfill sometime in 1997 in their original RCA cartons. We'll keep looking for a pallet with the next batch of 15G's.)
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  #15  
Old 11-19-2017, 09:42 PM
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Thanks, Pete!
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