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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: Re: Help this pathetic newbie to tubes : ) posted by Eli Duttman on August 5, 2006 at 14:27:55:
I talked with some older tube manufactuting persons in the 1970s. They stated the following.One factor was the vacuum in the tube. Vacuum is directly related to contaminates in the tube as well. Back in the 1970s, Dow Chemical stopped selling synthetic disspersion oil pump oil. The other available refined non-synethetic oil could not pull as high a vacuum and ended up at 10-4 Torr unless an interstage refridgerated cooler was placed inbetween the pump & tube.
So, a tube with an oil dispersion pumping system using the Dow Chemical oil could pull up to 10-5 Torr within reasonable drawdown time & the getter flash could pull up to another Torr point to 10-6 Torr. This seems to be the accepted quality minimum vacuum- 10-6 Torr. CRT tubes were ok with 10-5 Torr & some would even accept 10-4 Torr in say a rebuilt CRT tube.
Now, a high-speed turbine can easily pull 10-8 Toor & oil less magnetic bearing turbine pumps can pull 10-11 Torr. But, high speed turbine pumps cost much more money.
Some more 'secrets' exist in the GE MIT study back in the late 1950s that state how to manufacture a tube. Few copies exist as it was not published to the general public, or that is what I was told. It is as thick as a telephone book.
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Follow Ups
- Eli- 'to the grave'......... - Jimmy 15:07:10 08/05/06 (1)
- Adder......... - Jimmy 15:19:57 08/05/06 (0)
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