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Thread: Toroidal HV transformers?

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  1. #1
    Join Date
    Apr 2012
    Location
    Shropshire, England, UK.
    Posts
    243

    Default Toroidal HV transformers?

    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. #2

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    Linear Amps (UK) used a toroidal transformer in some of their designs, as I remember.

    BTW, Roger Banks, GW4WND owner of The DX Shop just acquired Linear Amps (UK) last week!!
    http://www.thedxshop.com/

    Geoff Brown, GJ4ICD used a toroidal in his 8877 design.
    http://www.gare.co.uk/gj4icd_8877_amplifier.htm

    Chris, G3WOS used a very flat E-I transformer in his portable 50 MHz, 8877.
    http://www.gare.co.uk/amplifier/index.htm
    Last edited by W9GB; 11-22-2012 at 04:31 PM.
    Nullius in verba

  3. #3

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    Is this one for ya linear? http://www.youtube.com/watch?feature=endscreen&v=E-FpeRf3RvQ&NR=1


    Love the size..... it's a whopper!

    Well, the ol' E & I cores, I always have problems getting the last couple in.

    Dave

  4. #4

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

  5. #5
    Join Date
    Jan 2006
    Location
    Wonder Lake, IL
    Posts
    1,486

    Default

    Quote Originally Posted by W0AAT View Post
    I have asked several US custom toroid winders and they won't do high voltage transformers.
    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??

    73,

    Bill N9DSJ

  6. #6

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    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?

    Dave

  7. #7

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    Quote Originally Posted by W0AAT View Post
    I have asked several US custom toroid winders and they won't do high voltage transformers.
    have you asked John at http://www.antekinc.com/index.php ?

  8. #8

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    Quote Originally Posted by KC2ZFA View Post
    have you asked John at http://www.antekinc.com/index.php ?
    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.

  9. #9

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    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 http://www.toroid.com/standard_trans...ormer_kits.htm

    Quote Originally Posted by N9DSJ View Post
    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??

    73,

    Bill N9DSJ

  10. #10

    Default

    Quote Originally Posted by W0AAT View Post
    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 http://www.toroid.com/standard_trans...ormer_kits.htm
    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.

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