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Thread: Anybody Know About Ballast Tubes?

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    Supporting Member Zer09's Avatar
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    Anybody Know About Ballast Tubes?

    I'm restoring a Weston Model 981 tube tester which uses an Amperite 5h-12 ballast. My personal tester is also a Weston 981 so I've been able to use that ballast to get it working and calibrated. But I'm going to sell this one and need to find a ballast for it. I can't find them anywhere. The Amperite website says they still have some in stock and sell them but I can't get a response from them. I've found a 6-13 but don't know if it will work, and I've seen universal ballasts where you just cut the wires for the resistances you don't use. The trouble is I can't find any data on the 5h-12 so wouldn't even know if unversals would work.

    This ballast tube is used as a current regulator on tubes with 600ma serial filaments. Information on ballast tubes is pretty sparse but if what I've read is correct the first number is the current rating and the second is voltage drop. So I am thinking 500ma and 12 volts. So the 6-13 should work?

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    Antique Radio Forums • Index page

    Quote Originally Posted by Zer09 View Post
    I'm restoring a Weston Model 981 tube tester which uses an Amperite 5h-12 ballast. My personal tester is also a Weston 981 so I've been able to use that ballast to get it working and calibrated. But I'm going to sell this one and need to find a ballast for it. I can't find them anywhere. The Amperite website says they still have some in stock and sell them but I can't get a response from them. I've found a 6-13 but don't know if it will work, and I've seen universal ballasts where you just cut the wires for the resistances you don't use. The trouble is I can't find any data on the 5h-12 so wouldn't even know if unversals would work.

    This ballast tube is used as a current regulator on tubes with 600ma serial filaments. Information on ballast tubes is pretty sparse but if what I've read is correct the first number is the current rating and the second is voltage drop. So I am thinking 500ma and 12 volts. So the 6-13 should work?

  3. #3
    Old Timer soundguruman's Avatar
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    Antique radio supply should have NOS ballast tubes. Call the manager and make a special request. Tubes and more .com

  4. #4
    Supporting Member Zer09's Avatar
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    Quote Originally Posted by soundguruman View Post
    Antique radio supply should have NOS ballast tubes. Call the manager and make a special request. Tubes and more .com
    They were the first place I tried and I got no response.

  5. #5
    Senior Member Enzo's Avatar
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    CALL them, no emails.
    Education is what you're left with after you have forgotten what you have learned.

  6. #6
    Senior Hollow State Tech Bruce / Mission Amps's Avatar
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    Is the 5h12S just used in the filament supply? Normally used for a constant current sourcing, I also wonder if it is a critical part of the calibration. Most old tube testers use the mult-itapped filament transformer for "life" testing and cathode sensitivity testing.
    Bruce

    Mission Amps
    Denver, CO. 80022
    www.missionamps.com
    303-955-2412

  7. #7
    Supporting Member Zer09's Avatar
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    Yeah, it is solely for the 600ma filament tube types. As a hobbyist/guitar player I don't see myself using any in my amp builds so I'm putting my ballast in the unit I'm selling and if I come across one at some point at a local hamfest or something I'll pick it up for my own.

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