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#1
12-12-2009, 10:23 PM
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I'm just about to embark on resusitating an early production RA-119 Royal Sovereign. Just acquired an NOS Raytheon 27RP4A CRT, which I will install as a substitute for the origional, and quite dead, 30BP4.
Have to fabricate a new mask for it, which should be a minor challenge. At least it's an aluminized 27BP4A. The resulting picture should be pretty good. LJB 
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#2
12-13-2009, 07:33 AM
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Dammitt, I wish I could find my "CRT" book...It told all about the 30BP4...From what I remember, they started having problems w/them right off the bat, due to lack of aluminisation, inadequate getters, etc. There were 2 builds of 'em, not very many on either one, & after the 2nd run ran out, DuMont offered to retrofit the puny little 27" tubes, complete w/a new mask, etc. Apparently, these were Muy Expensivo sets, & the owners raised Heck about 'em, so DuMont felt obligated to try & fix the problem. The book showed a picture of a workman setting the "cone" in a jig, prior to attaching the faceplate/screen. Looked like it must have been a fairly difficult/unwieldy process, the guy had to wrestle the fragile tube by himself, the whole business looked like it would have been like trying to manhandle a large, oddly-shaped washtub. I wonder what the scrappage rate was on these beasts...
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Benevolent Despot
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#4
12-13-2009, 12:06 PM
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Quote:
My favorite picture of the tube shows John McQueen (later at Southwest Vacuum) making the faceplate seal, in white shirt and tie. From ETF: http://www.earlytelevision.org/dumont_ra119.html jr Last edited by jr_tech; 12-13-2009 at 12:20 PM.
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#5
12-13-2009, 12:28 PM
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Given what was learned through perspiration and work on the 15gp22, this tube should be comparatively simple, albeit a very large metal to glass simple.
I wonder if this should be Scotty's next challenge. Wasn't there a 30" monochrome tube used in air traffic control displays?
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#6
12-13-2009, 08:50 PM
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The later large color CRT tubes(such as the Sony) contain lead, making them even heavier. I have changed a 17TP4 metal/glass tube in one of my Hoffmans. It was lighter than the 17HP4 all glass tubes also used by Hoffman.
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#7
12-14-2009, 11:45 AM
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Quote:
 Charles
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Collecting & restoring TVs in Los Angeles since age 10
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#8
12-13-2009, 12:47 PM
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That's the pic I remember from the CRT book, the guy had on a tie...An' $1875 would have pretty close bought you a new Ford or Chevy in '51...Things have changed a bit from '51...
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Benevolent Despot
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#9
12-13-2009, 12:57 PM
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"That's the pic I remember from that CRT book...the guy had on a tie...."
It is on page 157 of Peter Kellers book "The Cathode-Ray Tube, Technology, History, and Applications" (1991). On page 75 he shows the metal cone, nearly flat face, 22 inch P-7 DuMont CRT used for radar consoles.... I think that was the largest P-7 CRT that DuMont made for air traffic control. jr Last edited by jr_tech; 12-13-2009 at 01:38 PM. Reason: add 22" info
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#10
12-13-2009, 01:52 PM
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RCA did a larger 31" crt in 1938, albeit somewhat experimental - complete with its own vacuum pump ! See bottom of this webpage.
But that 30" 30BP4 monster is quite something. I think the largest mono CRT this side of the pond was 27" rectangular glass. TTFN, Jon
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#12
12-13-2009, 09:09 PM
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Well if it's confirmed that these sets did exist I wonder if any have survived somewhere?
I would guess the Royal Sovereign was downright mass produced compared to these.
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