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Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
Well of course I'm aware of the SAES corporate web site. I was wondering where I could get a small amount of "off-the-shelf" getters for hobby/experimental purposes without having to go back and forth requesting information, quotes, etc., filling out forms with personal data, explaining the application in detail, etc.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
In case it hasn't been posted here before -- here is a ham who scratch-built a batch of triode tubes, made a radio with them, and used it to communicate across the Atlantic Ocean. He doesn't seem to uses a getter, but bakes the guts pretty well with an oven, and an induction heater, and its own heater while the tube is on the vacuum pump. (11:45 to 12:30) At that level of homebrew technology, I imagine it would not be hard to make a getter.
Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308
Getters can help pull a harder vacuum than can be achieved otherwise, and help the lifetime of the tube. Have you been inspired to start glassblowing, jpsmith123, or just researching?
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
Uzzors wrote ...
Getters can help pull a harder vacuum than can be achieved otherwise, and help the lifetime of the tube. Have you been inspired to start glassblowing, jpsmith123, or just researching?
Try asking him where he got his.
Right now I'm just researching and accumulating some hardware and parts. (So far I have a two stage rotary vane vacuum pump, some molecular sieve material, a thermocouple gauge and various hardware odds and ends).
Anyway it seems to me that if a pulsed HV source were used, e.g., a Marx generator, the tube could be made fairly small and the vacuum requirements would be modest - say in the range of a few millitorr or so.
I'm also trying to figure out what would be the highest pulsed voltage that could be feasibly (and reasonably cheaply) generated and utilized (in a typical home workshop); a MV or 2 would be nice but maybe not practical. Right now I'm looking at several papers on HV air-core pulse transformer design and trying to do simulations using spice and CST studio.
I don't think it would be feasible (for me) to do anything with glassblowing. I suppose I will try to use off-the-shelf glass (or ceramic) to metal seals, maybe something with small conflat flanges and copper gaskets.
Depending on what type of getters are available, it might be feasible to make a sealed-off, demountable "semi-permanent" electron diode.
Registered Member #122
Joined: Fri Feb 10 2006, 12:55PM
Location: Milano Italy
Posts: 148
Try asking him where he got his.
i have a friend that work in a vacuum tube factory, scrounging some getters and some trashed glass items isn't so hard.
I don't think it would be feasible (for me) to do anything with glassblowing. I suppose I will try to use off-the-shelf glass (or ceramic) to metal seals, maybe something with small conflat flanges and copper gaskets.
Almost all of glass to metal seals readly available on the market require some glassblowing job: Making a glass to metal seal (except for wires and really small pins) is a tricky and time consuming job that usually require a large quantity of molten glass in ovens and a really slow cooling, at the contrary, a glass to glass and a metal to metal joint is much more easy and can be made with a torch, this is the reason why almost all scientific glassblowers usually prefer a pre-maded glass to metal seals for their tubes.
anyhow, a basic glassblowing tecnique isn't so hard to learn, and you could probably made your first working 2 electrode tube in 5-10 tries
Registered Member #2123
Joined: Sat May 16 2009, 03:10AM
Location: Bend, Oregon
Posts: 312
Long ago I worked at Hughes Aircraft - Carlsbad CA, where they had their vacuum tube/DVST manufacturing division. Glass-to-metal sealed pins were used in vast quantities, and each lot had samples inspected for glass whetting integrity prior to approval for use. You can't just blop some molten glass on a metal pin and expect it to seal. You should be able to buy these pins from some one.
Glass blowing/welding isn't that hard, but the trick is the post weld annealing to remove stress, otherwise you will watch in horror as your beautiful welds suddenly form cracks everywhere.
Conflat flanges with insulated electrical feed-throughs are certainly a viable option, but you need the other side, the thing you're bolting it to. And copper shear gaskets are use-once only. so have a bunch of them. Also may help to have a helium leak detector handy to check all conflat seals.
Registered Member #10
Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424
I suggest asking a neon workshop to buy a few cold cathodes from them. They act as their own getters. They are not expensive and even have the glass-friendly leads.
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Where can you buy getters?
