Bob, I remember a while back that someone was attempting to do an all-glass version of the 15GP22, thus eliminating the troublesome, leaky ultor ring. Do you (or anyone else) know the status of this project?

Progress is slow, it is still a work in progress. It still has to have the gun installed and be evacuated. It currently holds a good vacuum under test conditions.

This is what you're remembering.
http://www.earlytelevision.org/yurkon_15g_project.html

I think John's approach is likely to yield a good tube for him, but I doubt very much it could be repeated with any degree of success say three or four dozen times.

I hope the Epotec solution works, but I'm not holding my breath. There have been how many attempts to rebuild 15GP22s? And one successful tube (the 15GP22 in the ETF's Sparton) that appears to be little more than dumb luck.

Is it technically possible to rebuilt a 15GP22? Undoubtedly. Can a suitable solution be found to the problem, that is fairly trivial to repeat on dozens of tubes, and at a cost that a collector with a dud 15GP22 would be willing or able to pay? Maybe, maybe not. My gut says no.

My advice for anyone with a working 15G is twofold: treat it with kid gloves, and use the damn thing! I would rather get a solid year or two of enjoyment from the 15GP22 in my Westy, than turn the set on one day to find a bright pink neck and wish I had watched it more. That's why I'm having Nick do the restoration. It'll be done faster than I'd ever be able to complete it, and I'll be able to enjoy the set some.

I have a 1965 Allied catalog that does NOT list a 15GP22 in its CRT pages. That might be one indication of when new or rebuilt 15G's stopped becoming available.

I DID watch my 15GP22 (above) until it died by arcing. I watched NFL
and the World Champion Chicago Cubs games on it.

OF course they can be made to work again, as long as we can get
guns. At worst, due to the way the front end is made, the metal parts
could be installed in a completely new glass envelope. The problem
is getting alignment good enough for ok convergence.

The price I'll pay .... I'll give no number, but note that I own a TT5 and a Marconi 702.

I'm still considering replacing it, at least temporarily, by a rectangular Trinitron tube
that does not need convergence, and a fake external mask. I will try talking to people
about that at the ETF. If I ever succeed, it would make a great ETF talk. The problem of course
is horizontal drive ... maybe use the transistorized board of the donor set?

My comment about watching the set while the tube is good didn't apply to you Doug. You seemed to be playing your CT-100 very often, at least from what you posted on VK. That's the way it ought to be. Use it before you loose it...

I was referring to a collector that I know, who shall go nameless, who watches his restored CT-100 once, or at most twice a year, in order to "save the cathode material". You can have the best cathodes in the world, but if the tube is gassy, it doesn't matter.

All I know is that I am utterly fascinated by the CRT restoration efforts whether directed to 15G's or other tubes. The revisiting of the original RCA docs to understand the material science involved is epic.

The re-creation of the original or improved materials in this day of everything being labelled a carcinogen, and blocked from access to the general public or even technical workers, goes way beyond anything I've ever seen.

Special jigs and fixtures built from scratch with great attention to detail is an art form, as is the entire process. No doubt about it.

I live in the Seattle area where a certain Mr. Chihuly lives are creates fantastic glass sculptures. Many buildings in the area are endowed with his work. This effort is no less significant than that.

To all of you, RESPECT!!!

Couldn't agree more!