What I am calling a "re-neck" is something that occurs at the factory. For example, something goes wrong after the gun is sealed to the funnel, say a broken stem or a poorly annealed seal that cracks, or a defect is discovered in the gun... something like that. It is very easy at that point to simply remove the gun, seal on a new section of glass neck tubing and insert a new gun/stem assembly for a second try. If the labels on the tube look factory original, but the tube has an extra neck weld, I usually assume that it is a factory rework rather than a "rebuild".

jr

I'm firing up my time machine. My 1968 Allied catalog has 15GP22 "Colorama" tubes for like $135. Anyone want to chip in on a bulk buy?

Hmm. Only problem with this plan is that there isn't a whole lot of room in a DeLorean...

:D

-Ian

So, what is the layman's answer to this question? If you fire up an unknown CRT on a tester, are you risking anything for a future rebuild? Or do you just go ahead on the theory that the damage (if any) has already been done?

Phil Nelson

Maybe pack them well and ship them by the US Postal Service. Might be just arriving. I'll have to watch for the mail man.

---

If you fire up a gassy CRT at full heater voltage, it is very likely that the heater will quickly burn out. Since the heater and cathode are replaced during a rebuild, it is unlikely that a future rebuild would be adversely affected by doing so.

However, once the heater is burned out, a rebuild would be the ONLY option. No possibility of a rework (however slim) would exist. I guess that I would prefer to leave as many options open for as long as possible. Perhaps an attempt to seal the leaks followed by a getter re-flash and cathode re-activation could still rescue the tube, as long as the heaters remain intact. However, this is very unlikely and perhaps a waste of time and money, but at least the option remains open. If I had access to an RF generator and a getter "wand", I would try a getter re-flash in a New York Nanosecond... not much to loose!

jr

I have no need for a 15GP22.

It does occur to me, however, that since you'll only be carrying a load of 15Gs on the return trip, you'll have extra space during the departure.

We can make a deal. How much to send me one-way? :-)

I have a 21F_P22, Channel Master rebuild, that worked fine c.1995. About 5 years ago I awoke it from a long nap using a tester and noticed the filaments were very, very dim. Puzzled, I initially blamed it on the tester. Then I watched the filaments die one by one.

I'm not really worried that what I did was bad. Certainly the crt has air in it; finding/repairing the leak, and dealing with the air? Not an option, really. I just stuck it upstairs in my "dud" pile.

Did you test it? Today I found a note on #250527056091:

"Thanks to another Ebayer I was contacted by a very nice person who took the time to drive too my house and test this CRT. This person came in and tested The CRT with his custom made adapter for the CRT. As you can see this 15GP22 passed with Flying colors all three guns tested good. The CRT passed the ten second test. The Blew gun started to drop emission at 12 seconds after cutting power the green followed at 14 and the red gun at 15. Needless to say this is one good 15GP22."

I did the actual test as I was much closer to the seller's location. A homemade adapter makes the Beltron think it's testing a 21AXP22.

Pete

Wow... in most cases, you wouldn't expect an unknown 15G to pop up on ebay and test with such good results!

What is the make-up of this adapter? It sounds like there's a little more involved than simply getting the pins correct.

Pete, was there anything else interesting about the tube? For instance, the guy mentioned the neck weld... do you think it was actually rebuilt? Was there a date code on it?

Of course, none of that really matters considering those test results... it could be pink with purple dots.... someone is still going to want that tube!

I guess editorial flair souped up the basic nature of the adapter: just port the three G1, three cathodes, and filament over to a 20-pin Cinch connector.

Pete

There's no doubt in my mind that it is a factory rework weld. Date code is a bit hard to confirm via my photos, but it appears to be the 43rd week of '54, with only the '3' in question.

Pete