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PT question from an ST 70

Discussion in 'Eico Place' started by nj pheonix, Nov 4, 2018.

  1. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    I'm not sure if this is known. If you look at the schematic of an ST 70, The 2 6v windings (filaments) Greens and browns.
    The greens carry 6 tubes and the pilot light. The brown, 5 tubes.
    Would it be a fair assumption that the brown winding would have the same capacity or would one have a higher current rating than the other (to keep costs down.)?
     

     

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  2. nerdorama

    nerdorama AK member Subscriber

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    I'd say it's quite likely. Do you have a way to measure low resistances to compare the two windings?
     
  3. RWood

    RWood Nobody goes there anymore. It's too crowded. Subscriber

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    If you were really curious you could also measure and compare the current going through those windings.

    The earlier ST70s used a smaller PT than the later. I have had both and there is a noticeable difference in height (I used to have a picture). As I understand it, the filament windings on the earlier ones were prone to failure and then they beefed them up. Sure enough, the smaller PT of mine had a blown filament winding.
     
  4. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    I appreciate the input.
    I've been a little caught up. The victim (er, I mean donor isn t whole.
    Not sure I want to repair just to gut.
    Project will require an additional PT anyway, I was just trying to see my options.
    Would you know offhand (or would you be able to see the part # of the earlier or later versions?
     
  5. nerdorama

    nerdorama AK member Subscriber

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    I think Heyboer can make you a new power transformer to your specs. They need to know the mounting bolt pattern, whether standup or laydown style, and the voltage and current requirements. They may already have made an Eico ST-70 replacement. I had them make a power transformer to match the physical size of the ST-70 transformer but with a different B+ voltage. It was just a bit over $100 as I remember.
    John
     
  6. nj pheonix

    nj pheonix AK Subscriber Subscriber

    Messages:
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