[ohohyodafarted]

WRT: the tubes still under vacuum; We have rebuilt tubes that were under vacuum, and they developed a leak big enough to spoil the vacuum withing 30 days. Another builder out in California tried the same thing many years ago and ended up with the same result. They will go to air in about 30 days.

Tubes that have lost vacuum are even more problematic. It does not matter if the tube was good for 50 years and then suddenly sprang a leak, or it leaked very slowly for 50 years to the point where it had to much air in it. The fact is that it has a leak. A leak is a leak and even if it is a slow leak when you put it in the oven to evacuate, the heat and stresses of pulling a vacuum will make the leak even worse.

At some point down the road perhaps we might be able to seal the tubes with a special epoxy that we have experimented with in the past. The issue is that we will need to do a very long low temperature pump down so that the special epoxy does not burn up. But to do that we will need a facility that can do the experimental work. When Hawkeye closed it's doors several years ago, we lost our last good rebuilding facility where we could go and conduct experiments.

Until we have a facility with good equipment in which we can conduct experiments, we are going to be at a standstill with the 15G project.