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Re: [loopantennas] I Need a good soldering idea

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  • Jim Dunstan
    ... Hi, Is that de Phil or Dr. Phil ... hi. well let me see if I understand what the final configuration is going to be: an octoloop made of 3/4 copper
    Message 1 of 9 , May 7, 2005
      At 12:27 AM 5/7/2005 +0000, you wrote:
      Hi,

      Today I made the two halves of my copper "Octoloop", using the 3/4 inch copper
      pipe I bought the other day.  In over 50 years of radio work I've "melted a
      lot of solder", but this was my first experience soldering copper pipe.  I
      borrowed a propane torch, and while the joints may not be quite as "pretty" as
      a professional plumber would do, it went quicker and easier than I expected.
      Man, that torch heats the pipe up in a hurry 8^)

      Anyway, my intent is to thread the wire through the two halves of the loop
      BEFORE soldering the last joint?  I have nearly a full roll of 10ga insulated
      copper wire to wind it with.  With careful cajoling and a few unkind words, I
      would like to get at LEAST 4 complete turns in the pipe (this is to be a
      wideband untuned LF loop).  I'm sure two turns won't be difficult, 4 might be
      "pushing it".  What think ye?

      Anyway, I need ideas for soldering that last joint after the loop is wound.
      The wire is 10ga, black, stranded copper, with 20 mils MTW, THWN, or THHN
      insulation rated for 105 degrees C applications.  I touched my  soldering iron
      to it and it took awhile for the insulation to "melt" but I'm sure heat from
      the torch would take care of it almost immediately.

      Any Ideas on something that I could wrap around the wire to protect it while
      soldering, and which could "remain in the pipe" afterwards?

      IF it can't be done, I could probably solder that last joint and THEN wind the
      wire, but it might be difficult to get more than one turn around all the 45
      degree bends.

      73 de Phil,  KO6BB                                   

      Hi, 

      Is that de Phil or Dr. Phil ... hi.  well let me see if I understand what the final configuration is going to be:  an 'octoloop' made of 3/4" copper pipe formed into a complete circle up to one point where the ends are kept a small distance from each other which provides a shield 'GAP' and access to the internal 4 turn loop.  I would assume you would be using some kind of plastic pipe fittings at this point to secure the shield.

      Whatever, ..... so, how to get the 4 turns inside the pipe?  I would go ahead and solder one of the last joints forming the circle with a gap at the last joint.  There will be no problem providing a bit of a twist so each end of the pipe is clear and accessible.  Now I would solder 4 lengths of wire in parallel (of sufficient length to go around the loop).

      Run a single length through the pipe loop, solder the group of 4 to the end of the single wire and use the single wire to pull the 4 parallel wires through the pipe.  Put soap on the 4 wires to facilitate the process.  Now you simply have to cut the ends of the 4 wires and identify which ones are which and then solder and seal them to form the 4 turns.  Voila!  simple!

      Jim Dunstan, VE3CI
      Thunder Bay, ON

    • Henry Kolesnik
      If your gap is at the top you can use a matching pvc connection, it at the bottom get a matching pvc tee. you may have to solder on some threaded nipples. 73
      Message 2 of 9 , May 7, 2005
        If your gap is at the top you can use a matching pvc connection, it at the bottom get  a matching pvc tee.  you may have to solder on some threaded nipples.

        73
        Hank WD5JFR
        ----- Original Message -----
        Sent: Saturday, May 07, 2005 12:07 PM
        Subject: Re: [loopantennas] I Need a good soldering idea

        At 12:27 AM 5/7/2005 +0000, you wrote:
        Hi,

        Today I made the two halves of my copper "Octoloop", using the 3/4 inch copper
        pipe I bought the other day.  In over 50 years of radio work I've "melted a
        lot of solder", but this was my first experience soldering copper pipe.  I
        borrowed a propane torch, and while the joints may not be quite as "pretty" as
        a professional plumber would do, it went quicker and easier than I expected.
        Man, that torch heats the pipe up in a hurry 8^)

        Anyway, my intent is to thread the wire through the two halves of the loop
        BEFORE soldering the last joint?  I have nearly a full roll of 10ga insulated
        copper wire to wind it with.  With careful cajoling and a few unkind words, I
        would like to get at LEAST 4 complete turns in the pipe (this is to be a
        wideband untuned LF loop).  I'm sure two turns won't be difficult, 4 might be
        "pushing it".  What think ye?

        Anyway, I need ideas for soldering that last joint after the loop is wound.
        The wire is 10ga, black, stranded copper, with 20 mils MTW, THWN, or THHN
        insulation rated for 105 degrees C applications.  I touched my  soldering iron
        to it and it took awhile for the insulation to "melt" but I'm sure heat from
        the torch would take care of it almost immediately.

        Any Ideas on something that I could wrap around the wire to protect it while
        soldering, and which could "remain in the pipe" afterwards?

        IF it can't be done, I could probably solder that last joint and THEN wind the
        wire, but it might be difficult to get more than one turn around all the 45
        degree bends.

        73 de Phil,  KO6BB                                   

        Hi, 

        Is that de Phil or Dr. Phil ... hi.  well let me see if I understand what the final configuration is going to be:  an 'octoloop' made of 3/4" copper pipe formed into a complete circle up to one point where the ends are kept a small distance from each other which provides a shield 'GAP' and access to the internal 4 turn loop.  I would assume you would be using some kind of plastic pipe fittings at this point to secure the shield.

        Whatever, ..... so, how to get the 4 turns inside the pipe?  I would go ahead and solder one of the last joints forming the circle with a gap at the last joint.  There will be no problem providing a bit of a twist so each end of the pipe is clear and accessible.  Now I would solder 4 lengths of wire in parallel (of sufficient length to go around the loop).

        Run a single length through the pipe loop, solder the group of 4 to the end of the single wire and use the single wire to pull the 4 parallel wires through the pipe.  Put soap on the 4 wires to facilitate the process.  Now you simply have to cut the ends of the 4 wires and identify which ones are which and then solder and seal them to form the 4 turns.  Voila!  simple!

        Jim Dunstan, VE3CI
        Thunder Bay, ON

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        Put them in the appropriate folder, or create one.


      • john nelson
        I made my loop in two halves. The top joint is pvc so it is just a press fit and the bottom is a box with two friction connectors so I didn t have to do any
        Message 3 of 9 , May 7, 2005
          I made my loop in two halves. The top joint is pvc so
          it is just a press fit and the bottom is a box with
          two friction connectors so I didn't have to do any
          soldering after I pulled the wire.

          John N.
          --- Jim Dunstan <jimdunstan@...> wrote:
          > At 12:27 AM 5/7/2005 +0000, you wrote:
          > >Hi,
          > >
          > >Today I made the two halves of my copper
          > "Octoloop", using the 3/4 inch
          > >copper
          > >pipe I bought the other day. In over 50 years of
          > radio work I've "melted a
          > >lot of solder", but this was my first experience
          > soldering copper pipe. I
          > >borrowed a propane torch, and while the joints may
          > not be quite as
          > >"pretty" as
          > >a professional plumber would do, it went quicker
          > and easier than I expected.
          > >Man, that torch heats the pipe up in a hurry 8^)
          > >
          > >Anyway, my intent is to thread the wire through the
          > two halves of the loop
          > >BEFORE soldering the last joint? I have nearly a
          > full roll of 10ga insulated
          > >copper wire to wind it with. With careful cajoling
          > and a few unkind words, I
          > >would like to get at LEAST 4 complete turns in the
          > pipe (this is to be a
          > >wideband untuned LF loop). I'm sure two turns
          > won't be difficult, 4 might be
          > >"pushing it". What think ye?
          > >
          > >Anyway, I need ideas for soldering that last joint
          > after the loop is wound.
          > >The wire is 10ga, black, stranded copper, with 20
          > mils MTW, THWN, or THHN
          > >insulation rated for 105 degrees C applications. I
          > touched my soldering
          > >iron
          > >to it and it took awhile for the insulation to
          > "melt" but I'm sure heat from
          > >the torch would take care of it almost immediately.
          > >
          > >Any Ideas on something that I could wrap around the
          > wire to protect it while
          > >soldering, and which could "remain in the pipe"
          > afterwards?
          > >
          > >IF it can't be done, I could probably solder that
          > last joint and THEN wind
          > >the
          > >wire, but it might be difficult to get more than
          > one turn around all the 45
          > >degree bends.
          > >
          > >73 de Phil, KO6BB
          >
          > Hi,
          >
          > Is that de Phil or Dr. Phil ... hi. well let me see
          > if I understand what
          > the final configuration is going to be: an
          > 'octoloop' made of 3/4" copper
          > pipe formed into a complete circle up to one point
          > where the ends are kept
          > a small distance from each other which provides a
          > shield 'GAP' and access
          > to the internal 4 turn loop. I would assume you
          > would be using some kind
          > of plastic pipe fittings at this point to secure the
          > shield.
          >
          > Whatever, ..... so, how to get the 4 turns inside
          > the pipe? I would go
          > ahead and solder one of the last joints forming the
          > circle with a gap at
          > the last joint. There will be no problem providing
          > a bit of a twist so
          > each end of the pipe is clear and accessible. Now I
          > would solder 4 lengths
          > of wire in parallel (of sufficient length to go
          > around the loop).
          >
          > Run a single length through the pipe loop, solder
          > the group of 4 to the end
          > of the single wire and use the single wire to pull
          > the 4 parallel wires
          > through the pipe. Put soap on the 4 wires to
          > facilitate the process. Now
          > you simply have to cut the ends of the 4 wires and
          > identify which ones are
          > which and then solder and seal them to form the 4
          > turns. Voila! simple!
          >
          >
          > Jim Dunstan, VE3CI
          > Thunder Bay, ON



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        • Jim Dunstan
          ... Hi John, Your description is the usual method of constructing a shielded loop; the gap at the top and the feed point in a metal box at the bottom. The
          Message 4 of 9 , May 7, 2005
            At 12:54 PM 5/7/2005 -0700, you wrote:
            I made my loop in two halves.  The top joint is pvc so
            it is just a press fit and the bottom is a box with
            two friction connectors so I didn't have to do any
            soldering after I pulled the wire.

            John N.             

            Hi John,

            Your description is the usual method of constructing a shielded loop; the gap at the top and the feed point in a metal box at the bottom.  The standard method of feed in such a system is usually coax.  However this complicates tuning.  However, I have constructed shielded loops with no gap at the top with a combination gap and feed point at the bottom.  In this case I feed the loop with a balanced line (TV twinlead or 450 ohm line), terminating at my balanced antenna tuner.  It really simplifies things and allows tuning at a distance without complicated arrangements.

            If the loop is untuned then a RF transformer or voltage balun can be used to feed the shielded loop.  In the case of the loop in question with 4 turns of #10 wire .... I think that is what was mentioned ... pulling a bundle of 4 wires through the complete circle would be relatively easy.  Then soldering and insulating the ends (eg A2 to B1 and B2 to C1 etc will be an easy way to complete a 4 turn loop.  A1 and D2 would be the feed points.

            Granted my shielded loops were single turns within flexible 3/8 copper tubing.  The arrangement with the balanced feed line to a balanced antenna tuner makes a great SW antenna functional from below 5 MHZ to 21 MHZ (about 3' in dia.).  I have never seen this method of constructing a tuned shielded loop in the literature; but I assure you it works.

            Jim Dunstan
            Thunder Bay, ON

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