21AXP22 tragedy

[zenithfan1]

Sorry to hear that Bob, do you wanna take a close look at mine from the Wingate? Although I'm pretty sure it's down to air, but you can have it if you want.

[leadlike]

Sorry to hear about that, Bob-do 21ax's have a higher mortality rate during rebuilding, or did you just get a run of horrible luck?

[ohohyodafarted]

Mark, Thanks for the offer. I will take you up on your offer of the tube full of air. It is better than what I have. At least It will serve to fill the empty hole in a display set. And John and I are working on trying to find and seal leaks. We have purchased a Helium leak detector/ mass spectrometer to locate the leaks. Sealing them will be another whole issue.

Leadlike, Not sure what went wrong. Dont know if it was just bad luck, equipment malfunction or a human screw up. I have a pretty good hunch but can't say publically. None of these tubes have ever had a catastrophic failure using the slow 6hour ramp up/ramp down oven cycle at Hawkeye. And for 2 tubes to fail, both during the same oven cycle points a common problem. The tubes failed right when the oven reached 600F on the ramp up portion of the cycle, within 30 seconds of each other. Massive multiple cracking of the face plates of each tube indicating that the glass was under tension and not heating at the same rate as the metal bell of the crt.

So I am in need of rebuildable tubes to replace these that were destroyed. Any help will be greatly appreciated.