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Old 08-19-2008, 12:53 AM
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Bob Galanter
 
Join Date: Sep 2005
Location: Whitefish Bay, Wi (Milwaukee)
Posts: 1,053
I'm still here KB.

During the summer time I spend as much vacation time as I can scrape together at our cottage in the last vestiges of the wilderness in the great northwoods of Wisconsin. Last week we heard wolves howling at the full moon at 2AM. That was a first for me.

I am going to test the 15gp22 I bought (the one under vacuum) tomorrow if time permits.

The 15g project is moving along. John Folsom and I have funded and ordered a new batch of stems to mount rebuilt 15G gun assemblies to.

I have perfected a method of removing the base sockets from the 15g without damaging the socket so that it can be reused on the rebuilt crt.

I have machined the tooling to EDM the old cathodes out of the 15g gun assembly using the EDM machine where I work. So now we can reliably remove the cathode assemblies from the 15g guns in preparation for sending the guns off to be rebuilt.

I have also been working (without much success) trying to develop a method to test the leaker 15g envelopes in an attempt to see if they can be sealed successfully with Vacseal compound. Early attempts have been a total failure using a laboratory grade vacuum pump and electronic vacuum meter I purchased for about $250.

I sopke to the former head of Rauland Picture Tube, and he told me that I needed to obtain a Helium leak dector if I wanted to test the envelopes for leaks. So it looks like we will have to obtain a Helium leak detector, which is a very expensive piece of scientific laboratory equipment. We need to pre-qualify leaker envelopes to make sure that they will hold a vacuum after we rebuild them. Because if they leak after they are rebuilt, we have wasted a lot of time, effort and BIG money if the rebuilt tubes fail to hold vacuum. So we need to be sure the envelopes are going to hold a vacuum before we attempt a rebuild. The envelopes have to be pumped down to a maximum of 10 to the minus 6 MM of Hg, and bathed in a shower of Helium while connected to the Helium leak detector. If there is a leak, the Helium atoms (because they are the second smallest atom known) will be sucked through the leak into the envelope of the crt and the Helium leak detector will be able to count the number of Helium atoms it finds in the vacuum stream flowing out of the crt. Essentially we are talking about a Helium mass spectrometer.

One of these units goes for about $25K to $30K new. I have located one in California that appears to be in relatively good condition, and at a reasonable price, but it still aint cheap.

Anyone have a couple thousand extra dollars they want to donate to the project to buy a Helium Leak Dector ???

That's all for now,
Bob
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