Plate transformer question

Discussion in 'Amateur Radio Amplifiers' started by KN4CTD, Apr 20, 2019.

ad: L-HROutlet
ad: l-rl
ad: MessiPaoloni-1
ad: Left-3
ad: L-MFJ
ad: Subscribe
ad: Left-2
  1. N2EY

    N2EY XML Subscriber QRZ Page

    No it doesn't.

    The voltage across the entire secondary is 5640 volts RMS, with taps at 4520 volts RMS. The voltages you gave are each side of center-tap, not the whole secondary.

    The catalog says 2820-2260-0-2260-2820.

    Yes - but there's more: those voltages are based on choke-input supply with mercury-vapor rectifiers (about 15 volts), and allow for a certain amount of voltage drop in the filter chokes.

    Good thing you wrote "almost nobody".

    The choke(s) would indeed be quite large, though not as big and heavy as the transformer. And you'd need a pretty hefty bleeder resistor, because the choke-input filter requires a considerable current draw at all times to maintain critical inductance.

    If one is going to go that far, might as well use 866As or 872As and get the whole effect.

    Old-school choke-input supplies do have some advantages: Better power factor, better crest factor, and you can turn them off when receiving without a big thump you go to transmit.

    One word: NO.

    Put a full wave bridge rectifier and capacitor filter across that transformer secondary and you'll get close to 8000 volts - until something explodes.

    btw, transformers such as that one often aren't designed to operate with the center tap ungrounded.

    Check the'll see....

    73 de Jim, N2EY
    Last edited: Apr 24, 2019
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I missed the 2820-2260-0-2260-2820 rating entirely. Only saw the two voltages and guessed they were the full-winding RMS values.

    But if that was a really bad guess, then this transformer is really only suited to a choke-input filter and that adds weight, size and complexity I'd rather not deal with unless I had a lot of time to kill -- a real lot.

    Easier to find a modern transformer that's appropriate for a bridge or a doubler, and waste a lot less time (and weight, and complexity, and cost...):p
  3. KN4CTD

    KN4CTD Ham Member QRZ Page

    Thanks everyone for the input.......I’ll never buy anything again that I’m unsure of. I will not be using. I will place an ad to see if someone has one of those old transmitters would want it for free......if not, scrap.
  4. AH7I

    AH7I Ham Member QRZ Page

    73, -Bob
    Last edited: Apr 25, 2019
  5. AH7I

    AH7I Ham Member QRZ Page

  6. N2EY

    N2EY XML Subscriber QRZ Page

    I hope someone takes it.
  7. N8FVJ

    N8FVJ Ham Member QRZ Page

    The old transformers have high secondary winding resistance vs new.
    KN4CTD likes this.

Share This Page