Speaking of 30" Dumonts
 

Anyone seen one of these?

http://blog.modernmechanix.com/2007/...ross-the-room/

I wish. Looks like Allen DuMont at the control panel.

Phil

Same here. What an amazing picture.

Must have been a prototype.

How heavy is the 30 inch tube? Being a metal/glass, I can't imagine it's that bad...

The facepate alone could easily have weighed over 100 lbs.

Just a guess here, but most faceplates on metal CRTs were quite thin, because they were strengthened by being placed in very strong compression as the metal to glass seal cooled. I suspect that the glass is not much more than 1/4-3/8" thick.

Update: I just crawled into my attic and weighed a 22" metal cone DuMont radar tube (P-7 phosphor) and it was only 33 pounds. a 16AP4 metal cone CRT is only about 11-12 pounds.

jr

The 30BP4 has a @ 3/8" thick faceplate. It's not too heavy.

I know...I got one.

[QUOTE=Eric H;2961767]Anyone seen one of these?

Not one but two when I was a kid. There was a DuMont dealer on a busy street in St. Petersburg, Fl. where I grew up. They had the 30 inch set in the picture and also a two piece version that had a remote control console on a huge umbilical cable so the CRT cabinet could be placed up high in a bar and the controls in a more convenient place to be operated. I dragged my dad down to their store and got a demo!

They prolly thought a 30" TV was a Miracle of the Age then...

Amazingly, the tube isn't heavy at all! The face is fairly thin glass, and the metal cone is also very thin. The reason they were able to do that is that te convex shape allows for plenty of strength, unlike the bigger flat Trinitron WEGA tubes which weigh 100s of pounds due to thick glass. The chassis on the Gen I DuMont Royal Sovereign is ridiculously heavy, but the Gen II is a smaller single chassis with click tuner, and isn't too heavy. I've moved the Gen II by myself, including lifting it into the pickup. The Gen I is a ball-buster though.

Only a couple of years ago, I finally got around to pulling the tube out of (formerly) my Royal Sovereign, which is recapped and working well. It had been in my fire in '88, and the soot had gotten between the tube and the safety glass. The glass for some dumb reason is installed from the inside of the cabinet, thus the tube must come out to clean it. It was a big job due to fear of death, or worse yet harming the possibly only excellent 30BP4 around, but I did it. The present owner was just as nervous; couldn't even stand to watch.


Here's a pic of the Gen I set, showing how shallow the 30BP4 is. (photo circa 1995). I got that set from a garage sale, and found out that it belonged to actress Jeanette McDonald. That set, after I cleaned it up (bad tube), is in the same collection today as the Gen II set.
Charles

http://i104.photobucket.com/albums/m...ntRS_early.jpg

While it may not have been that heavy, it's interesting that the screen diameter was actually 28 1/4 in. The mounting flange brought it out to 30 1/8 in. I suppose if Dumont hand extended the flange 7/8 in. we'd be calling this a 31" tube! :D

...

I wonder if Sony (or somebody) ever thought about making a metal-cone crt in later years? Too much to engineer?

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

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...

What was the MSRP on a Royal Sovereign, BTW?

When I was a little kid, I saw one at a local home show... Great looking TV! The salesman told me " just like your $25 savings bond... 1875 with a couple more zeros" so unless he was yanking my chain, it was $1875.00 on the west coast.

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

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?

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...

"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

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

"somewhat experimental - complete with its own vacuum pump !"

Very cool ! Thanks for the link. Wonder if I could fit a pump in the base of my CT-100? :scratch2:

jr

re the 30-in. Dumont. I saw one too when I was a kid about 12-years-old in the main area of the Lafayette Hotel in Atlantic City NJ. I walked in there and my jaw dropped. The management had roped off an area on the left side of the room and placed rows of folding chairs for guests. As you reported, this set was a number of feet above the floor, making it easily visible. My parents were friends of the owner, who had this hotel and another in Florida, so I knew something about the guy: he was a businessman first, but a techie at heart. In the late '40's, he played a Hallicrafters SW receiver on the other side of the same room for -- he explained when I asked -- the guests. I recall at the time being surprised that a hotel owner would do something so interesting and neat. When he saw the 30-in. Dumont ad, you know he had to have one and had the wherewithal to justify the bucks.

Pete

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.

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.

Can we imagine what the 43" Trinitron tube weighed???? Ball-buster supreme! I have the service manual which shows the total weight of the TV (PVM-4300u) at 440 lbs, and that's a plastic table model :smoke:

Charles

Got to see this 30 inch DuMont RS & take pictures of it in 1987... Good to know it is still going strong.. Keep up the great work of preserving our History... Find More kaye Halberts to !!!!!