Moron alert again for rebuilding 15GP22's

[julianburke]

I'm sure this got your attention but I didn't know what else to call it.

Regarding the CT100 that just ended on EVILbay for good money, had a comment added at the bottom where the seller can put your question into the ad. The moron told him that ETF is rebuilding these tubes and thought he would like to know this to tell prospective buyers.

Hell, we'd all like to know this----if it was true!!! After the very nice and well written info that was obtained in the experiment of trying to rebuild 2 of these fragile tubes that had 100% failure, you would think that info would have "leaked" out--no pun intended! Instead someone is saying that they are rebuilding them now. Moron alert!!!!!

Uhhh Steve, you aren't doing anything up there at ETF that you haven't told us about, have you???

UPDATE: One of the talks at the ETF was Bob Galanter (and John Folsom) giving their account of the two 15G's they tried to rebuild at Hawkeyes. Everyone was leaning on their chair to hear this one! It was very informative and promising. The main problem is the joining of the faceplate to the bell of the tube. Newer tubes use a frit which is a special glass epoxy to join the two pieces of glass which was not available at the time of the 15G production. They joined the two pieces (actually 3-a ring washer of sorts in the center where they electrically welded them together) of metal which were each annealed to the glass workpiece and apparently worked when manufactured but developed leaks along the last 50+ years. It also poses the nightmare when trying to rebuild the tube as it leaks, leaks and leaks!

[Steve McVoy]

There will be exciting news from France at the convention.

[julianburke]

I have heard someone else is working on this project in another country but they are encountering similar problems. Since I am/was experienced in tube rebuilding, I would like to see a product that seals vacuum leaks where metal and glass are annealed.

I have often thought that just manufacturing *NEW* 15GP22's (even in china) would be a better alternative with better technology albeit an expensive project. It would be nice if a manufacturer could build say, 500 tubes in the $300-500 bracket. The more made, the lower cost per tube as you couldn't build just 100 as they would be in the $2000-3000 bracket.

[Whirled One]

Originally Posted by julianburke

I have often thought that just manufacturing *NEW* 15GP22's (even in china) would be a better alternative with better technology albeit an expensive project. It would be nice if a manufacturer could build say, 500 tubes in the $300-500 bracket. The more made, the lower cost per tube as you couldn't build just 100 as they would be in the $2000-3000 bracket.

That sounds like it would work at first, but I bet they'd end up being a lot more expensive than $300-$500. After all, if they can make something as simple as a 2A3 filament triode and have it retail for over $100 (currently $108 each at Antique Electronic Supply-- made by JJ Electronic in the Slovak Republic), why bother making something as complex as a 15GP22 that only has a very limited market? (Very few pieces of equipment exist that use 15GP22's, and it's unlikely any new such ones will be made, whereas the audiophile crowd probably still builds new amplifiers around 2A3's.)

In any case, it's really a case of demand and what the market will bear, versus cost of development and construction. It's far easier to make (and sell) a 2A3 or a 6L6 compared with a 15GP22, and people will pay enough for them to make it worthwhile.

[kx250rider]

An investor might be willing to pony up for 100 of them, since there are enough CT-100s in the hands of collectors to support that many new tubes in the next 10-20 years. But the catch would be that there would need to be a platinum guarantee that the new tubes wouldn't sit and fail on the shelf, leaving an investor with an unwanted tax loss. Probably a net per-unit mfg cost of $1000 would be do-able, as they tubes could likely sell for $1850 (my guess). People who would never have DREAMED of putting that much money up for a static inventory before, might do it now, as there's no other place to put money right now if you want more than 2% return, or so.

Charles

[julianburke]

You're right. I never thought I'd ever see 12AX7's go for $1200+ either but it seems like there are those who will. I still don't see how anyone can tell the difference between a good 12AX7 and a $1200 one. Electrons for this matter don't know the difference in a good tube to a good tube. I'll stick to my RCA's or whatever 12AX7 that I have on hand!

BTW, anyone wanting to pony up $1200 for a GOOD 12AX7, I have plenty available.

[kvflyer]

Originally Posted by julianburke

You're right. I never thought I'd ever see 12AX7's go for $1200+ either but it seems like there are those who will. I still don't see how anyone can tell the difference between a good 12AX7 and a $1200 one. I'll stick to my RCA's!

You know why you "don't see how anyone can tell the difference between a good 12AX7 and a $1200 one." Because there isn't one. Smoke and mirrors, nothing wrong with your perception...

[miniman82]

My $0.99 CONN organ 12AX's sound as good as a Telefunken does...
But I am half deaf from jet noise on the flight deck, maybe that has something to do with it?

[Findm-Keepm]

Originally Posted by miniman82

But I am half deaf from jet noise on the flight deck, maybe that has something to do with it?

How true of me too! I tell folks my $1,900 Stereo system (binaural hearing aid system) was provided to me courtesy of Uncle Sam! I was just fine until they started low power testing F/A-18C's in Hangar Bay 1, with no soundproof barrier between them and the shop(s) I worked in.

Heck, I'd pony up for a 15GP22 and have fun trying to drive it with a later, less rare RCA chassis. Modifying the chroma section would be the most challenging, I imagine.

Cheers,

[Adam]

Speaking of morons, epay, and early color television, watch this: http://cgi.ebay.com/RCA-1949-COLOR-T...0#ht_500wt_924

This guy makes a video of the RCA color TV sign he's selling, in which he picks up the sign, drops it, you hear it break, then the video still goes on, shows the tequila bottle (from which he's been surely drinking), then he falls over. The "good" part is towards the end.

[bandersen]

Bizarre! Why would someone post that unedited? Did he even watch it ?

[Phil Nelson]

Bizarre is an understatement. Hope he saves that to show to his grandkids. After he drops the sign and breaks it, you can see a second liquor bottle on the counter over to the left.

Phil

[Steve McVoy]

As all of you who attended the Early Television Convention know, a successfully rebuilt 15GP22 was on display. Last year, the tube was in our warehouse. It had a broken neck, and was full of debris of all sorts. No one thought to protect it because it appeared to be too far gone to ever be rebuilt.

Jerome Halphen shipped it to France, where RACS made it work again, using frit glass to stop the massive leaking at the glass-metal junction. They attached an new neck, stem and a rebuilt gun.

When the crew at the convention, led by Pete Deksnis, tried it in a set, they couldn't get the right colors. Finally it was discovered that RACS, not having a complete tube with gun to work with, had installed the gun 120 degrees off from its proper orientation. The leads on the tube socket were changed to accomodate the wrong gun position, and a nice color picture was obtained.

Now RACS will attempt two more tubes. If they are successful, the 15GP22 will live on. Many thanks to John Folsom and Bob Galanter who spent hours and thousands of dollars getting this project going, and to Jerome for working with RACS to get the tube rebuilt.

More will be posted on the ETF website soon.

[Eric H]

I watched the presentation on the rebuilding of that tube and it was fascinating to say the least.

They took probably the least likely candidate you could find for rebuilding, neck broken for decades, leaky seams, spider webs in the broken neck, and yet miraculously, it works again!

I guess that answers the question of "Do Phosphors go bad when exposed to air for a long time"

BTW, is there a link where we can watch the video again?

[Steve K]

I'm not sure if a "before" picture of the 15G that RACS rebuilt has been shown before but here is a picture I took of it two years ago at ETF. The hammer you see in the picture was swung by Pete Deksnis!

Steve