I have two ancient GE-KR9 and two GE-KR9A Kenotron rectifiers. I got them to use for my [censored by diyaudio policy on HV stuff], but I now noticed one of the tubes has a crack in the ribbed section. I put cyanoacrylate glue on it but I'm guessing vacuum has already been lost.
My question is twofold--can I on a mere propane torch flame fix the crack, and can I reestablish sufficient vacuum from a water aspirator (I can run ice water through it with a pump and the cold water has pretty low vapor pressure)? Also, about dropping in some getter material?
Alternatively, I'll trade these tubes for a solid state bridge or discrete rectifiers that can rectify 130 kV RMS AC at 25 mA DC.
My question is twofold--can I on a mere propane torch flame fix the crack, and can I reestablish sufficient vacuum from a water aspirator (I can run ice water through it with a pump and the cold water has pretty low vapor pressure)? Also, about dropping in some getter material?
Alternatively, I'll trade these tubes for a solid state bridge or discrete rectifiers that can rectify 130 kV RMS AC at 25 mA DC.
Hi
You can normally melt glass with a propane flame, but you've to be sure there is already the atmospheric pressure inside, otherwise it will form a bubble that will blow inside.
Restoring the vacuum is much more difficult: most tubes require a hard vacuum, that can only be attained by diffusion or turbomolecular pumps.
LV
You can normally melt glass with a propane flame, but you've to be sure there is already the atmospheric pressure inside, otherwise it will form a bubble that will blow inside.
Restoring the vacuum is much more difficult: most tubes require a hard vacuum, that can only be attained by diffusion or turbomolecular pumps.
LV
If you've got a crack, the getter is gone. The getter does not have the capacity to convert a poor vacuum to a hard one, it is useful for taking an already good vacuum into a superb one. At minimum, you'd have to evacuate to a micron or so using a rough pump/diffusion pump combo, use glass-blowing methods to seal up the tube, then flash the getter (already been done when the tube was first made, so you're SOL).
Cyanoacrylate will pass air like a colander passes water.
Cyanoacrylate will pass air like a colander passes water.
I can do resealing since the nipple is quite large, and I can easily stretch it out even more. But looks like I can't reach sufficient vacuum.
Finding solid state rectifiers that can meet my requirement is proving difficult. I see very cheap 20 kV 10 mA diodes on eBay, but I'd need a 100 in parallel/series to make a bridge with sufficient overhead in current and voltage... Higher voltage and current ones are very expensive. It's cheaper for me to wind a filament transformer for these old tubes than to buy the expensive solid state rectifiers, and is why I'm so interested in fixing there.
Anyone know if there's a place that can fix tubes, i.e. can do sufficient vacuum and maybe replace the getter? I can get the glass repaired no problem by a retired scientific glassblower I know for next to nothing, but he doesn't have vacuum.
Finding solid state rectifiers that can meet my requirement is proving difficult. I see very cheap 20 kV 10 mA diodes on eBay, but I'd need a 100 in parallel/series to make a bridge with sufficient overhead in current and voltage... Higher voltage and current ones are very expensive. It's cheaper for me to wind a filament transformer for these old tubes than to buy the expensive solid state rectifiers, and is why I'm so interested in fixing there.
Anyone know if there's a place that can fix tubes, i.e. can do sufficient vacuum and maybe replace the getter? I can get the glass repaired no problem by a retired scientific glassblower I know for next to nothing, but he doesn't have vacuum.
An externally hosted image should be here but it was not working when we last tested it.
i've seen , where refrig- and ac compressors,were/ are used
for 'vacuum forming'
less $$ than-
http://www.torontosurplus.com/redirect.php?middleframe=http://www.torontosurplus.com/mys/mys80.htm
how well this would work, i don't know.
at least give this a try.
for 'vacuum forming'
less $$ than-
http://www.torontosurplus.com/redirect.php?middleframe=http://www.torontosurplus.com/mys/mys80.htm
how well this would work, i don't know.
at least give this a try.
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