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Re: Tamura MET-46 transformer sources?

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  • jbboater
    I plan to try an audio transformer as well. I am using a shielded audio cable and I plan to cut the wire in half, then solder the transformer between the two
    Message 1 of 13 , Jan 1, 2011
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      I plan to try an audio transformer as well. I am using a shielded audio cable and I plan to cut the wire in half, then solder the transformer between the two halves I just cut.

      However, I am not sure if I need to connect the shield wire from each half together. Seems to me, if I do, then I defeat the purpose of the isolation transformer (interrupting the ground loop).

      But, I really do not know. So, if someone might already know the answer, I would greatly appreciate it.

      Basically, do I leave the cut shield 'dangling' or do I connect them together?

      Thanks!

      Jeff

      --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
      >
      >
      > ----- Original Message -----
      > From: "g8voip"
      > Subject: [softrock40] Re: Tamura MET-46 transformer sources?
      >
      >
      > >I wonder if you were planning to try and use those transformers in the I/Q
      > >lines? Looking at the data sheet, the only reference to bandwidth is 300Hz
      > >to 3.5kHz, so probably pretty useless for SDR use.
      > > and I was surprised to see some improvement when fitting them to my SDR
      > > set up. Whether the small improvement is worth the expense is another
      > > matter.
      >
      >
      > I have tried a couple of transformer types.
      > One the usual 600/600 modem, the other Pico with a poorer LF like the one
      > above.
      > Both seemed to work satisfactorily within their limits but neither would
      > allow decoding of DRM.
      >
      > 73 Alan G4ZFQ
      >
    • Brian Lloyd
      ... Leave the shields isolated. You are correct in thinking that reconnecting the shields would recreate your ground-loop. -- Brian Lloyd, WB6RQN/J79BPL 3191
      Message 2 of 13 , Jan 1, 2011
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        On Sat, Jan 1, 2011 at 2:47 PM, jbboater <jburke42@...> wrote:
         

        I plan to try an audio transformer as well. I am using a shielded audio cable and I plan to cut the wire in half, then solder the transformer between the two halves I just cut.

        However, I am not sure if I need to connect the shield wire from each half together. Seems to me, if I do, then I defeat the purpose of the isolation transformer (interrupting the ground loop).

        But, I really do not know. So, if someone might already know the answer, I would greatly appreciate it.

        Basically, do I leave the cut shield 'dangling' or do I connect them together?

        Leave the shields isolated. You are correct in thinking that reconnecting the shields would recreate your ground-loop.

        --
        Brian Lloyd, WB6RQN/J79BPL
        3191 Western Dr.
        Cameron Park, CA 95682
        brian@...
        +1.767.617.1365 (Dominica)
        +1.931.492.6776 (USA)
        (+1.931.4.WB6RQN)

      • jbboater
        THanks for the quick reply Brian, It just dawned on me, won t I need a transformer for the tip and a second transformer for the ring? If so, how do I connect
        Message 3 of 13 , Jan 1, 2011
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          THanks for the quick reply Brian,

          It just dawned on me, won't I need a transformer for the tip and a second transformer for the ring?

          If so, how do I connect the return or bottom of the transformer?

          I would think I would connect two wires to one side of the shield, and they would each connect to both return sides of the transformer.

          Not sure about this now that I'm about ready to cut and solder some wires...

          --- In softrock40@yahoogroups.com, Brian Lloyd <brian-wb6rqn@...> wrote:
          >
          > On Sat, Jan 1, 2011 at 2:47 PM, jbboater <jburke42@...> wrote:
          >
          > >
          > >
          > > I plan to try an audio transformer as well. I am using a shielded audio
          > > cable and I plan to cut the wire in half, then solder the transformer
          > > between the two halves I just cut.
          > >
          > > However, I am not sure if I need to connect the shield wire from each half
          > > together. Seems to me, if I do, then I defeat the purpose of the isolation
          > > transformer (interrupting the ground loop).
          > >
          > > But, I really do not know. So, if someone might already know the answer, I
          > > would greatly appreciate it.
          > >
          > > Basically, do I leave the cut shield 'dangling' or do I connect them
          > > together?
          > >
          > Leave the shields isolated. You are correct in thinking that reconnecting
          > the shields would recreate your ground-loop.
          >
          > --
          > Brian Lloyd, WB6RQN/J79BPL
          > 3191 Western Dr.
          > Cameron Park, CA 95682
          > brian@...
          > +1.767.617.1365 (Dominica)
          > +1.931.492.6776 (USA)
          > (+1.931.4.WB6RQN)
          >
        • Brian Lloyd
          ... Yes. You want a separate transformer for both the I and Q channels. ... Both transformers will be connected the same way. The shield coming from the
          Message 4 of 13 , Jan 1, 2011
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            On Sat, Jan 1, 2011 at 5:25 PM, jbboater <jburke42@...> wrote:
             

            THanks for the quick reply Brian,

            It just dawned on me, won't I need a transformer for the tip and a second transformer for the ring?

            Yes. You want a separate transformer for both the I and Q channels. 


            If so, how do I connect the return or bottom of the transformer?

            Both transformers will be connected the same way. The shield coming from the SoftRock will be shared by the primaries of the two transformers. The secondaries will share the shield going to your sound-card. 


            I would think I would connect two wires to one side of the shield, and they would each connect to both return sides of the transformer.

            Yes.


            Not sure about this now that I'm about ready to cut and solder some wires...


            I think you have it.

            --
            Brian Lloyd, WB6RQN/J79BPL
            3191 Western Dr.
            Cameron Park, CA 95682
            brian@...
            +1.767.617.1365 (Dominica)
            +1.931.492.6776 (USA)
            (+1.931.4.WB6RQN)

          • jbboater
            Hi Brian, Thanks again for your help. I will give this a try today. In case someone else wonders which transformers I am using, based on the information I
            Message 5 of 13 , Jan 2, 2011
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              Hi Brian,

              Thanks again for your help. I will give this a try today. In case someone else wonders which transformers I am using, based on the information I found, I am using the Radio Shack 420-1374 audio isolation transformer.

              Perhaps not the best, it was the quickest and easiest transformer to find locally.

              Thanks again,

              Jeff

              --- In softrock40@yahoogroups.com, Brian Lloyd <brian-wb6rqn@...> wrote:
              >
              > On Sat, Jan 1, 2011 at 5:25 PM, jbboater <jburke42@...> wrote:
              >
              > >
              > >
              > > THanks for the quick reply Brian,
              > >
              > > It just dawned on me, won't I need a transformer for the tip and a second
              > > transformer for the ring?
              > >
              > Yes. You want a separate transformer for both the I and Q channels.
              >
              > >
              > > If so, how do I connect the return or bottom of the transformer?
              > >
              > Both transformers will be connected the same way. The shield coming from the
              > SoftRock will be shared by the primaries of the two transformers. The
              > secondaries will share the shield going to your sound-card.
              >
              > >
              > > I would think I would connect two wires to one side of the shield, and they
              > > would each connect to both return sides of the transformer.
              > >
              > Yes.
              >
              > >
              > > Not sure about this now that I'm about ready to cut and solder some
              > > wires...
              > >
              >
              > I think you have it.
              >
              > --
              > Brian Lloyd, WB6RQN/J79BPL
              > 3191 Western Dr.
              > Cameron Park, CA 95682
              > brian@...
              > +1.767.617.1365 (Dominica)
              > +1.931.492.6776 (USA)
              > (+1.931.4.WB6RQN)
              >
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