2" neck glass for round color CRT's wanted
 

Looking for 2" soda lime glass Neck Glass tubing for rebuilding 21" round color crt's. Borosilicate glass is not suitable. If you have old 2" neck flares for picture tube rebuilding, or any random lengths of 2" soda lime glass tubing, in your collection of old tv stuff; please let me know.

Also, if you have dead 21" round tubes that you can donate please let us know. We can salvage 2" neck glass from dead 21" round color crt's in order to use the neck glass to rebuild other tubes.

If you can't find anything better, I've got a 21FBP22 I've been saving for rebuilding if that ever restarts... That tube had a nice picture until it spontaneously cracked between 2 of the base leads and went to air.

Is this part of the 15GP22 rebuilding project?

Yes Tom. I am turning over everything that John Folsom and I had accomplished to John Yurkon and Nick Williams. I would not expect anything to happen in the short term, but with John Folsom having passed on, and my health in decline, passing the baton on to John and Nick is the logical thing to do.

One of the primary pieces of material for rebuilding 15GP22 and 21" round color tubes is 2" soda lime NECK GLASS. We have searched world wide and nobody is making soda lime glass tubing in 2" diameter. All they make now is 2" borosilicate and due to the difference in the coefficient of expansion, borosilicate is incompatible with soda lime glass. So unless we can find some NOS lengths of 2" soda lime glass, we will need to salvage 2" neck glass from dead tubes that are headed for the dump.

I also discovered that dead 7JP4 tubes are also suitable donors for 2" neck glass.

Each tube to be rebuilt, requires about 3 to 4 inches of 2 inch neck glass to extend the neck on the tube, in order to install a new gun assembly.

If you are going to convention we can talk more about all of this at convention if you like. There is still a long long way to go, but every journey starts with the first step and a will to persevere.

Why do you need to extend the neck, unless its a "necked" tube? Can't you just attach the new pin section to the remainder of the neck after you saw off the old gun?
This would of course require a saw setup.

Removing the gun shortens the neck. If you just inserted a new gun in the shortened neck, the distance from the gun to the face of the tube would be shorter and that would not be acceptable.

There is no way to remove a gun without shortening the neck somewhat.

View the video I authored about how picture tubes are rebuilt.

https://antiquetvguy.com/WebPages/Cr...MoviePage.html

I think Doug was expecting you to reuse the original base lead button instead of using a new one... Which might be possible, but would be a lot more involved... Also more chance for the button to crack and fail.

I talked to our department glassblower, who sometimes faces the exact same problem.
He said he will send a couple of suggestions to try, if you have not already tried them.

More important, there is glassblower's convention in a week or two which he will attend. He will enquire about possible solutions.

In the meantime, do you have the glass data, i.e. expansion coefficient?

Doug McDonald

The glass is Corning 0120 Potash Soda Lead The coefficient of thermal expansion (CTE) for Corning 0120 glass is approximately 93.5 * 10-7 cm/cm/ degree C almost identical to Corning 0080 Soda Lime glass

Bob, I saved the gun portion of a necked 21" and will dig it out/measure it. I'm not sure if I still have any dud roundie tubes but will check that as well.

Hi to all,
Hi Bob,

Glad! to see some action on roundy color CRTs via Nick W. & John Y.

Neck tubing: have you queried or gone through the inventory of ex-RACS items currently at the ETF ?
I'm fairly sure there was neck tubing + NOS B&W and color guns (probably inline types).

There was a (not too detailed) inventory list for Customs when the container was shipped to the US.

Best Regards
jhalphen
Paris/France

I will be going to ETF convention. Nick and John Yurkon are also going to attend. If you have neck glass to donate we can do that at convention.

RE: RACS stuff. We will be searching all that came from them while at convention.

Thanks

Since I'm not too far from you and I'm not sure how practical bringing the tube to the ETF is is with what I have buyers for, if you still need neck glass after the ETF reach out to me and I'll drop it off on my way home from work.

Last I heard the CRT rebuilding room may not be accessible at the ETF Convention this year. I think it is being used as TV storage since the museum has recently received a ton of sets that have been donated to the museum. So I think it is full of TVs right now. That may change, but it may not. Just a heads up. I will be there on Thursday and will scope it out.

Hi to all,
Hi Bob & Nick,

ETF 2026 Convention is now over, heard in YT video coverage that Nick had visited.

Did you find some adequate 2" glass tubing, ex-RACS inventory or otherwise?

If you've found some, what happens next?

Best Regards
jhalphen
Paris/France

Hi Jerome,
We did find a couple lengths of 0120 Corning 2" glass. It was from the items that came from Hawkeye. It was manufactured by Corning and in the original shipping box from Corning. Shipping label stated that it was sold to a TV repair shop in the US who had a small rebuilding operation. The CRT rebuilding room was packed full of TV sets and it was difficult to conduct a further search. We did find 20 Pin stems that came from RACS. A further search will need to be done when the rebuilding room at ETF is more accessable.

In a year or so Nick plans to start some limited experimentation. Nick took home from the ETF, the Varian mass spectrometer Helium leak detector that John Folsom and I donated to the ETF. So Nick will be able to perhaps do some experiments in sealing leaky 15G's. Progress will be slow, but Nick is our best hope. He has the equipment and skill. Everything we found at ETF went home with Nick, along with 8 dud 15GP22's and 12 Rebuilt guns 15G guns that John Folsom and I had rebuilt at Southwest Vacuum.

Glad to see efforts are somewhat coming back for this now! Sadly, I moved and am in the south now, so my help is limited. I do have a couple 21J/F tubes that need rebuilt. One has an intermittent cathode, and the other one went purple/gone to air. There might be one or two more bad jugs sitting over there at the Boiling Springs warehouse in SC thats slowly being cleaned out. One of them was necked.

I may or may not get it rebuilt we shall see, so if not, its still a source of glass.