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Running only 2 6V lamps on a hammond PT filament tap

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  • Running only 2 6V lamps on a hammond PT filament tap

    I'm running an amp with all 12V filaments, and so I have a separate filament tranny.

    I am however running 2 6.3V lamps on the unused 6.3V winding of the Hammond 270DX PT that I'm using in the amp.
    Is there any problem to doing this? Only having the lamps on there? I feel like this really shouldn't matter, but just thought I'd check.

    My total current draw on the HT secondary tap for the amp is in the neighborhood of 90mA, and the PT is rated for 104mA on the HT secondary winding.
    I'm also not using the 5V tap, and only the 2 lamps on the 6.3V tap.. Still the PT seems to get quite warm. I can hold my hand on it, but I'm just surprised how warm it's getting. Thought perhaps it had something to do with my strange use of the 6.3V winding.

  • #2
    Should be fine, unused taps are often just taped off and it is not a problem.
    The only concern I would have is that some voltages (AC from the PT) may be higher with the xfmr in a lightly loaded state, so check that they are at acceptable levels. The heat issue sounds fairly normal to me.
    Originally posted by Enzo
    I have a sign in my shop that says, "Never think up reasons not to check something."


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    • #3
      Originally posted by g-one View Post
      Should be fine, unused taps are often just taped off and it is not a problem.
      The only concern I would have is that some voltages (AC from the PT) may be higher with the xfmr in a lightly loaded state, so check that they are at acceptable levels. The heat issue sounds fairly normal to me.

      Voltages read fine. My wall outlet is 119.5VAC, and I'm connected to the 125VAC primary tap, so that brings things down a bit. I'm actually reading 6VAC on the 6.3VAC tap.

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      • #4
        On the last amp I built I used the unused 5v tap to light the pilot lamp.
        It works great and is not so overly bright.
        Also it took the pilot lamp off the 6v which was heavily loaded.
        T
        "If Hitler invaded Hell, I would make at least a favourable reference of the Devil in the House of Commons." Winston Churchill
        Terry

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        • #5
          Originally posted by big_teee View Post
          On the last amp I built I used the unused 5v tap to light the pilot lamp.
          It works great and is not so overly bright.
          Also it took the pilot lamp off the 6v which was heavily loaded.
          T
          How much current would a 6V lamp draw?

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          • #6
            Originally posted by thehoj View Post
            How much current would a 6V lamp draw?
            Somewhere around 150ma.
            But my amp on EL 34s makes the PT pretty warm so every little bit helps.
            Like I said the Lamp is brighter than I like on 6.3v, and my 5 volt tap was unused and a good alternative.
            T
            "If Hitler invaded Hell, I would make at least a favourable reference of the Devil in the House of Commons." Winston Churchill
            Terry

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