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Re: [softrock40] Coax connection for Softrock v6.2

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  • Bill Dumke
    alejovarona, If they are short connections, it won t matter. But I would leave room for an RF isolation transformer, to get rid of AC ground loops from the
    Message 1 of 5 , Oct 6, 2007
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      alejovarona,

      If they are short connections, it won't matter. But I would leave room
      for an RF isolation transformer, to get rid of AC ground loops from the
      antenna ground to your rig ground if you are using an unbalanced antenna
      like a 40m ground mounted vertical for example. This will minimize the
      center spike and might even eliminate it. My isolation transformer has
      about 3 inches of lead length on either side of it, and it does not hurt
      anything at 40 meters.

      Bill wa9pwr

      alejovarona wrote:
      > Out of utter ignorance:
      > Is it safe to solder two wires to a bnc plug and connect them to the
      > SoftRock v6.2 antenna pins?
      > The plan is to solder two wires to a bnc plug that is attached to my
      > enclosing and to connect them to the Softrock board using Molex/Harwin
      > crimp housings. I wonder though if I'll mess the tranmission line
      > impedance.
      >
      >
      >
      >
      > Yahoo! Groups Links
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    • Alejo Varona
      Bill, The wires lenght will be about 5 inches or less for a Softrock 30m/20m flavour. I don t know whether they are short enough, I presume yes but I ll
      Message 2 of 5 , Oct 6, 2007
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        Bill,
        The wires lenght will be about 5 inches or less for a Softrock 30m/20m flavour. I don't know whether they are short enough, I presume yes but I'll appreciate a confirmation from you.
        Another thing you speak about is the RF isolation transformer. How do you build one?

        ----- Original Message ----
        From: Bill Dumke <billd@...>
        To: softrock40@yahoogroups.com
        Sent: Sunday, October 7, 2007 1:58:58 AM
        Subject: Re: [softrock40] Coax connection for Softrock v6.2

        alejovarona,

        If they are short connections, it won't matter. But I would leave room
        for an RF isolation transformer, to get rid of AC ground loops from the
        antenna ground to your rig ground if you are using an unbalanced antenna
        like a 40m ground mounted vertical for example. This will minimize the
        center spike and might even eliminate it. My isolation transformer has
        about 3 inches of lead length on either side of it, and it does not hurt
        anything at 40 meters.

        Bill wa9pwr

        alejovarona wrote:

        > Out of utter ignorance:
        > Is it safe to solder two wires to a bnc plug and connect them to the
        > SoftRock v6.2 antenna pins?
        > The plan is to solder two wires to a bnc plug that is attached to my
        > enclosing and to connect them to the Softrock board using Molex/Harwin
        > crimp housings. I wonder though if I'll mess the tranmission line
        > impedance.
        >
        >
        >
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
        >
        >
        >




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      • Bill Dumke
        Alejo, All you need is a toroid and some wire. Though the binocular cores seem to work best for this application. I just picked what I thought to be a T50-6
        Message 3 of 5 , Oct 7, 2007
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          Alejo,

          All you need is a toroid and some wire. Though the binocular cores seem
          to work best for this application. I just picked what I thought to be
          a T50-6 core out of my junk box and wound some #26 enameled wire bifilar
          on it until it filled up. (This is not optimal by the way for all the
          HF Ham bands, but it worked fine for me on 40 meters. You can use the
          "mini ring core calculator" software free from the Internet if you want
          to. ) To make the bifilar windings just put one end of each wire in an
          electric drill chuck and secure the opposite ends close together in a
          vise or something like that. Let the drill spin until you get about
          about a 4 turns per inch twist. Then you just connect one winding to
          your rig and the other winding to the "isolated ground" antenna
          connector on your box. You can buy these for BNC connectors. They use
          white plastic to insulate the whole connector from the chassis. You
          could probably insulate your connector with some plastic yourself if you
          want to.

          I think I got my isolated ground BNC connectors from either Digikey or
          Mouser.

          5 inches sounds kind of long for 20 meters, but I don't know for sure.
          I used about 3 inches each side of my isolation transformer at 40
          meters. Mine is just laid out on a table. I haven't put it in a box as
          yet. But I recommend to always make wires like this as short as
          possible. It becomes more important at higher frequencies.

          Bill wa9pwr

          Alejo Varona wrote:
          > Bill,
          > The wires lenght will be about 5 inches or less for a Softrock 30m/20m flavour. I don't know whether they are short enough, I presume yes but I'll appreciate a confirmation from you.
          > Another thing you speak about is the RF isolation transformer. How do you build one?
          >
          > ----- Original Message ----
          > From: Bill Dumke <billd@...>
          > To: softrock40@yahoogroups.com
          > Sent: Sunday, October 7, 2007 1:58:58 AM
          > Subject: Re: [softrock40] Coax connection for Softrock v6.2
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          > alejovarona,
          >
          >
          >
          > If they are short connections, it won't matter. But I would leave room
          >
          > for an RF isolation transformer, to get rid of AC ground loops from the
          >
          > antenna ground to your rig ground if you are using an unbalanced antenna
          >
          > like a 40m ground mounted vertical for example. This will minimize the
          >
          > center spike and might even eliminate it. My isolation transformer has
          >
          > about 3 inches of lead length on either side of it, and it does not hurt
          >
          > anything at 40 meters.
          >
          >
          >
          > Bill wa9pwr
          >
          >
          >
          > alejovarona wrote:
          >
          >
          >> Out of utter ignorance:
          >>
          >
          >
          >> Is it safe to solder two wires to a bnc plug and connect them to the
          >>
          >
          >
          >> SoftRock v6.2 antenna pins?
          >>
          >
          >
          >> The plan is to solder two wires to a bnc plug that is attached to my
          >>
          >
          >
          >> enclosing and to connect them to the Softrock board using Molex/Harwin
          >>
          >
          >
          >> crimp housings. I wonder though if I'll mess the tranmission line
          >>
          >
          >
          >> impedance.
          >>
          >
          >
          >
          >
          >
          >
          >
          >
          >>
          >>
          >
          >
          >> Yahoo! Groups Links
          >>
          >
          >
          >
          >
          >
          >
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          >
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