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Thread: Need to rebuild a high voltage vacuum thyratron for an old copper vapor laser

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    Default Need to rebuild a high voltage vacuum thyratron for an old copper vapor laser

    Does anybody know if it's possible to rebuild a vacuum tube thyratron from an old Oxford copper vapor laser? The original one is rated for 2000 hours. It was made by Marconi, but they don't make it anymore. I talked with Oxford yesterday and they said once that thyratron is spent, the laser is garbage unless I can source a new vacuum thyratron or rebuild it? The model is an Oxford CU25. How hard would it be to rebuild one of these?

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    E2V Technologies is the successor to Marconi and still makes Hydrogen Thyratrons. You have a Hydrogen or Deuterium Thyratron. "Vacuum Thyratron" would be a oxymoron by definition. The Russians, The Chinese, Pulsed Power Solutions, Inc. L3, GLVAC, Richardson Electronics, and Excelitas all make something similar to that tube.
    !
    Note they are brazed together in an oven at 1300-1400' C, followed by some TIG welding steps. So only the largest ones, designed for military and linear accelerator use, are re-buildable, by design. Most of the brazes are a one shot deal, they don't come apart, as the tolerances used ensure a press fit.
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    https://frank.pocnet.net/other/EEV/H...trons_1978.pdf might have your part listed.
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    Last edited by mixedgas; 08-24-2016 at 06:42.
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    Thank you very much, that's good news. I will be getting the specs on the thyratron today. Then I can cross reference it. I want to be able to operate the laser for years not just hours.

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    Here's some details from the range of thyratron's that were in my CU-10's:
    http://danielbriggs.co.uk/Thyratron_info.pdf

    More or less all you need to know. Put the kettle on, make a cup of tea + have a read
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    Quote Originally Posted by mixedgas View Post
    Note they are brazed together in an oven at 1300-1400' C, followed by some TIG welding steps. So only the largest ones, designed for military and linear accelerator use, are re-buildable, by design. Most of the brazes are a one shot deal, they don't come apart, as the tolerances used ensure a press fit.
    How about de-brazing the thyratron in an oven, so as to open it back up, replace the aluminized ceramic casing with a brand new one, replacing the anode if needed, then rebraze it back together. I'm sure there is some thing I'm missing here, but there is decidedly very little on hydrogen thyratron manufacturing techniques online. None of the companys you listed have that particular thyratron, nothing cross referenced. I've got to figure out a way to secure a solid source of fresh thyratrons for my beloved CV laser. My other choice is this so far...

    E2V has a nice replacement for the cx1535 thyratron, it's only a few centimeters taller. However, they only have two left and they will cost me $13,000 each for a grand total of two thousand hours of run time.

    A dismal situation. Maybe I can start my own thyratron making company? I'm just trying to stay positive here. I will figure out a way around this problem.

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    Russian Hydrogen Thyratrons are a lot cheaper then that. And there is no way the original cost on that tube was 13k/ There is plenty of info on how they are made out there, if you have academic or military credentials to access it. Problem is, materials for a one off are not cheap. No one is going to want to slice, polish, and metalize just one piece of Alumina for you. The jigging and materials alone would burn up 5K$ at commercial prices. These are made using economies of scale. There are producers in China, India, USA, and Russia.


    Steve
    Last edited by mixedgas; 10-31-2016 at 12:13.
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    Cx1735 is (I assume) the one I was quoted for as being 13k in price (by e2v). I will call again tomorrow to be sure. Based on the datasheet comparison to the cx1535. How do I source a Russian made thyratron of the same electrical and physical specs that the Oxford Cu laser was designed for? I would commit to make at least 20 units as a production run, therefore to offset the price of manufacturing materials purchase. Plus I'm confident that anyone else out there with a functioning Oxford Cu laser would like to buy some new cx1535 thyratrons. Heck I wouldn't mind offering a rebuild service for them. These lasers were meant to run for years by design. It would be a shame to relegate them to the scrap yard because of one discontinued switch...
    I'm gonna dissect that switch and figure out how to rebuild it as a rebuildable. I just need to know how bigger more complex ones (in the same genre) are rebuilt. That information will tell me how to take it apart and what parts need to be replaced or remanufactured. It will also provide a template on how to redesign the cx1535 as a rebuildable thyratron.

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    Been talking to E2V about using the cx1835a thyratron as a replacement for the cx1535, it has also been discontinued, but they have a few left. They have two in inventory and have tested them for me. Just testing them, they said stopped their regular production at the factory. The price they quoted on these is: $13,950 for each. I'm sure that is fine if you are the military or a university with unlimited research budget. That's way out of my price range though. Is that what they costed originally? And they time out after 2000 hours? It should be more like 20,000 hours at those prices. Does anybody have any of these lying around that I can buy? Even if they are "spent", "used up". Any other solutions?

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    - There is no such word as "can't" -
    - 60% of the time it works every time -

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