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Toroidal HV transformers?

Discussion in 'Amateur Radio Amplifiers' started by 2E0ILY, Nov 21, 2012.

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  1. 2E0ILY

    2E0ILY Guest

    What's the current status with regard to toroidal single phase HV transformers for plate supplies circa 5kV and up to about 2 amps? I believe a Swedish company may specialise in these, anyone used them instead of a conventionally cored HV transformer? pros and cons? thanks.
  2. W9GB

    W9GB Ham Member QRZ Page

    Last edited: Nov 22, 2012
  3. G4COE

    G4COE Ham Member QRZ Page

  4. W0AAT

    W0AAT XML Subscriber QRZ Page

    I have asked several US custom toroid winders and they won't do high voltage transformers.
  5. N9DSJ

    N9DSJ Ham Member QRZ Page

    At one time I worked for a transformer manufacture; we were pretty much a build-to-order job shop (no real inventory). The issue for us was that although we made smaller toroids, larger ones were manufacturing equipment limited. We made huge transformers for Sandia National Labs and such but not toroids. Is there a reason you are limited to a toroid transformer??


    Bill N9DSJ
  6. G4COE

    G4COE Ham Member QRZ Page

    Just thinking wouldn't there be an issue with the winding to winding layer insulation? Unlike a standard transformer you have more layers but over a shorter area compared to say a ring wound transformer... just a thought.

    Wouldn't you have a greater voltage difference between beginning and the end of one layer?

  7. KC2ZFA

    KC2ZFA Ham Member QRZ Page

    have you asked John at ?
  8. WA7PRC

    WA7PRC Ham Member QRZ Page

    Their biggest off-the-shelf unit, pn AS-15T950, can't do anywhere near what is required for a legal-limit amplifier. Assuming a nominal 55% efficiency, you'd need to pull 1500 / 0.55 = 2727W from the power supply, and that transformer can't deliver anywhere near that much output. I wonder if one of their custom winds would be as inexpensive as the big E-I xfmr I rewound. My investment is about $150 for 10# of 18 AWG polyimide-coated wire + NMN paper. I expect to be able to get well over 3KVA out of it. :cool:
  9. W0AAT

    W0AAT XML Subscriber QRZ Page

    At the time I was looking for a small compact transformer for a portable VHF amplifier. Since then I have custom would a couple toroids myself from primary kits. Big enough for 600 watt class amplifiers. Kit page

  10. WA7PRC

    WA7PRC Ham Member QRZ Page

    1440VA seems to be the about limit in a single core xfmr, and they seem to be all 117/120V only primary. I s'pose for twice that VA, one could buy two and connect the primaries in series (or stack two cores) to run it on 240V and get about 3KVA. The only question then is the breakdown voltage rating. By nature, my split bobbin EI core xfmr has very low leakage, and I'm still money ahead with it.
  11. AC0H

    AC0H Premium Subscriber QRZ Page

  12. G4LNA

    G4LNA Ham Member QRZ Page

    I always wondered how they made them, now I know, very impressive. I know they usually wind the secondary first being the thicker wire than the secondary so there is less chance of crushing the wire. I suppose that is a problem winding HV toroids, which winding do you put on first? They can obviously do it because they make them.
  13. 2E0ILY

    2E0ILY Guest

    Thanks for all the replies, looks like I will be keeping my fingers crossed that the floor of my upstairs shack doesn't fail when I get yet another heavy transformer up here :) Seems high current, high voltage toroidals are still a rarity, was hoping for a more compact and lighter weight option. Cheers.
  14. G4LNA

    G4LNA Ham Member QRZ Page

    I've just retrieved a 1:1 2KVA toroidal from a bit of equipment at work, it is a big beast, I suppose it could be multiplied up, but I think you have to be careful doing that sort of thing with a toroidal.
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