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How do I wire a toggle switch for an HF amplifier power supply ?

Discussion in 'Amateur Radio Amplifiers' started by KC5SCK, Jun 17, 2017.

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  1. AF6LJ

    AF6LJ Ham Member QRZ Page

  2. WA7PRC

    WA7PRC Ham Member QRZ Page

    The schematic of the Heathkit SB-220 amplifier's primary circuit (that I posted before your post here) shows you why. There are TWO "live wires", L1 and L2. It's a "balanced line", with two conductors 180° of of phase with each other, and neither conductor is common to ground.
  3. W1QJ

    W1QJ Ham Member QRZ Page

    The European 240vac Roger is Line to Neutral which is what our 120vac is. So, you break one line (hot) on your 240v and we break one line (hot) on our 120v. BUT.....Our 240vac is a LINE to LINE voltage so we HAVE to break both lines for safety purposes. That's the difference.
  4. G3YRO

    G3YRO Ham Member QRZ Page

    Well our 415V supply is like that . . . connected between 2 wires of the 3-phase supply that runs under the street. (240V is obtained by just connecting ONE of those to ground)

    But I thought your 240V was usually just an extra winding on your small power transformers you mount on poles?

    Regardless of that . . . a lot of equipment only has a Single pole on/off switch . . . and even on your 240V mains, it will still turn it off ! (and it's only dangerous if you poke around inside the equipment with it plugged into the mains)

    Roger G3YRO
    Last edited: Jun 21, 2017
  5. KA9JLM

    KA9JLM Ham Member QRZ Page

    It is 240 with a center tap. We use the center tap to get 120.
  6. G3YRO

    G3YRO Ham Member QRZ Page

    Well if one side of the transfornmer is grounded that becomes what we call Neutral, and you get 120V on the Centre Tap, and 240V on the top end of the transformer. (so only one leg is "live" on 120V or 240V)

    OR . . . do you ground the Centre Tap . . . so you have 240V across each end of the transformer . . . and 120V between EITHER end and ground?

    Roger G3YRO
  7. AF6LJ

    AF6LJ Ham Member QRZ Page

    The center tap is grounded.
  8. G3YRO

    G3YRO Ham Member QRZ Page

    Oh right . . . presumably it's done that way so that if you touch the 240V mains, you only actually get a 120V shock?

    I guess that's all part of the American paranoia about electric shock from the Mains . . . which I gather stems back to all the false publicity put out by the Edison Company to try and discredit Tesla's AC Mains system . . .

    I've touched our 240V mains probably hundreds of times over the years . . . and I'm still here !

    Roger G3YRO
  9. AF6LJ

    AF6LJ Ham Member QRZ Page

    No Roger Paranoia has nothing to do with it.
    This is how AC was implemented in this country from the start.
    Besides people here don't go around touching the mains. :cool:
  10. WR2E

    WR2E Ham Member QRZ Page

    Roger said:

    Roger as a boy:


    Roger now:

    G3ZBP likes this.

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