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Re: [loopantennas] Re: Transmitting loop

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  • Henry Kolesnik
    Perhaps I could have been a little clearer, let me try again. VSWR is a ratio that depends on the mismatch and the voltage is a fucntion of power transmitted.
    Message 1 of 28 , Aug 2, 2005
      Perhaps I could have been a little clearer, let me try again. VSWR is a ratio that depends on the mismatch and the voltage is a fucntion of power transmitted. P=E^2/R. The higher the power, the higher the voltage. Reducing power reduces the voltage but the ratio stays the same. The power is lowered to a level that won't zap the finals.

      73
      Hank WD5JFR
      ----- Original Message -----
      From: W1EOF
      To: loopantennas@yahoogroups.com
      Sent: Tuesday, August 02, 2005 4:30 PM
      Subject: RE: [loopantennas] Re: Transmitting loop


      Henry - Sorry but I have to disagree on your explanation of how the
      protection circuits work: Cutting back power does absolutely nothing to
      adjust the SWR down. All it does is attempt to lower the power so that the
      devices max power is not exceeded. SWR is a ratio of forward to reflected
      power. Lowering the power output from the radio will not change that ration
      one bit.

      Like any other circuit, there are compromises. They don't want the
      protection circuit kicking unnecessarily so the trigger has a time constant.
      If a pulse comes along that's great enough, and fast enough, you *WILL* lose
      your finals. This is way it's always always a good idea to disconnect your
      radios from the antenna when they are not in use.

      SWR on transmission lines is a complicated topic. For simplicity sake, you
      want to keep your SWR on coax lines as low as possible. Down in the area of
      1.5 or 2.0 to 1 is good. Look at the loss tables to see what happens at a
      particular frequency as your SWR climbs. You can easily lose 50% or more of
      your power before it reachs the antenna. Problem generally gets much worse
      as frequency goes up.


      73,

      Mark W1EOF

      -----Original Message-----
      From: Henry Kolesnik [mailto:kolesnik@...]
      Sent: Tuesday, August 02, 2005 5:12 PM
      To: loopantennas@yahoogroups.com
      Subject: Re: [loopantennas] Re: Transmitting loop


      Richards
      Any solid state rig purchased in the last 25 years hs automatic power
      reduction so the power output will depend on the SWR the rig's finals see
      and it will cut back power so that the SWR is always less than about two or
      three to one.
      ----- Original Message -----
      From: Richards
      To: loopantennas@yahoogroups.com
      Sent: Tuesday, August 02, 2005 3:36 PM
      Subject: Re: [loopantennas] Re: Transmitting loop


      I am a novice just studying for the first exams.... I gather you
      guys are in agreement on one thing...

      Whether or not you fry your output transistor, having that big
      standing wave really sucks... right?

      ///////////// Richards /////////////////
      ===========================================

      dldorrance wrote:

      >Hank, thanks for the distinction. However, even if the wave is
      >re-reflected (back and forth around the speed of light about
      >


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      If you've got links, post them in the Links section!
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      For uploading images, I prefer the Files section since Photos only allows
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      Put them in the appropriate folder, or create one.



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      [Non-text portions of this message have been removed]



      If you've got links, post them in the Links section!
      http://groups.yahoo.com/group/loopantennas/links

      For uploading images, I prefer the Files section since Photos only allows everyone (except the uploader and moderators) to see a max of 300x400.
      http://groups.yahoo.com/group/loopantennas/files

      Put them in the appropriate folder, or create one.



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    • Steve Baker
      Whether or not you fry your output transistor, having that big standing wave really sucks... right? Yes....standing waves are hard to surf. ...
      Message 2 of 28 , Aug 2, 2005
        "Whether or not you fry your output transistor, having
        that big standing wave really sucks... right?"

        Yes....standing waves are hard to surf.

        --- Richards <jruing@...> wrote:

        > I am a novice just studying for the first exams....
        > I gather you
        > guys are in agreement on one thing...
        >
        > Whether or not you fry your output transistor,
        > having that big
        > standing wave really sucks... right?
        >
        > ///////////// Richards /////////////////
        > ===========================================
        >
        > dldorrance wrote:
        >
        > >Hank, thanks for the distinction. However, even if
        > the wave is
        > >re-reflected (back and forth around the speed of
        > light about
        > >
        >


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      • vze3v8dt@verizon.net
        Hello, Richards. Good luck with your studies. In general large SWR is a bad thing, however there are things that can be done to deal with it, some more
        Message 3 of 28 , Aug 2, 2005
          Hello, Richards. Good luck with your studies.

          In general large SWR is a bad thing, however there are things that can
          be done to deal with it, some more efficiently than others. Generally,
          a blanket statement about something excludes some possibilities which do
          work okay. An example with a high SWR is a center fed Zepp that is fed
          with twin lead transmission line, like 300 to 600 or more ohms
          characteristic impedance. At some frequencies there will be a good
          match between the antenna (load) and the transmission line. The next
          problem with that is that most rigs are set up with 50 ohm coaxial
          output (source impedance) so some method to convert from 50 ohms to 300
          - 600 ohms is needed. Sometimes people use baluns to do this, however
          they also have limitations and issues. For example, they introduce an
          extra loss element and at high power that generates heat, and so at high
          enough power levels with enough heat the ferrite or powdered core of a
          balun saturates causing the balun to become nonlinear and not work very
          well (as well as generating harmonics?). Maybe another way instead of
          using a balun is to use an antenna tuner (although most of them that
          have balanced line terminals also have baluns). I like my Johnson KW
          Matchbox tuner which doesn't have a balun and is quite efficient (at
          least on the "standard" (pre-WARC79) ham bands from 80 to 10m. Now,
          take for example an antenna impedance that is not the same as the
          characteristic impedance of the transmission line, then there is an
          SWR. The main problem with that is loss of signal in the transmission
          line as the reflected wave goes between from the antenna and the tuner
          and back again (and again and again ...). In coax this is a problem
          because the losses are high however using balanced feeders (twin lead)
          the losses are surprisingly small. So, it becomes an engineering
          problem, trying to minimize losses with tradeoffs of different
          architectures for a given design parameters. In general resonant
          antennas work very well and should be fed with coax or could be fed with
          balanced feeders and an appropriate impedance transformation at some
          point. Non-Resonant antennas should NOT be fed with coax (unless some
          tricks are done, I suppose), but would be better fed with balanced
          (twin-lead) feeders and use of a good "transmatch". Oh, by the way, the
          term "antenna tuner" is generally a false nomenclature unless it is
          actually employed at the end of the feedline at the antenna. However,
          most "antenna tuners" people use in their hamshacks actually help the
          transmitter match the load at that point. The only place there is a low
          SWR then is between the radio and the tuner, a matter of a few feet, but
          there could still be high SWR on the long run from the tuner to the
          antenna.

          You can learn a great deal more about this if you pick up a book called
          "Reflections" by Walt Maxwell, W2DU. He used to be the department head
          of the antenna group at a company that was at one time called RCA where
          communications and research satellites were developed and built. He
          retired before I was employed there in 1990, but it was evident that he
          was still greatly respected. The original version of the book was
          published by ARRL but later they ignored the science and tended to more
          folklore so they dropped his publication. It is again published in
          softcover as "Reflections II" and I think is in the 2nd or 3rd printing
          the last I knew and published now by WorldRadio Books.

          73,

          Mark, NK8Q


          Richards wrote:

          >I am a novice just studying for the first exams.... I gather you
          >guys are in agreement on one thing...
          >
          >Whether or not you fry your output transistor, having that big
          >standing wave really sucks... right?
          >
          >///////////// Richards /////////////////
          >===========================================
          >
          >dldorrance wrote:
          >
          >
          >
          >>Hank, thanks for the distinction. However, even if the wave is
          >>re-reflected (back and forth around the speed of light about
          >>
          >>
          >>
          >
          >
          >If you've got links, post them in the Links section!
          >http://groups.yahoo.com/group/loopantennas/links
          >
          >For uploading images, I prefer the Files section since Photos only allows everyone (except the uploader and moderators) to see a max of 300x400.
          >http://groups.yahoo.com/group/loopantennas/files
          >
          >Put them in the appropriate folder, or create one.
          >Yahoo! Groups Links
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >


          [Non-text portions of this message have been removed]
        • dldorrance
          Richard, you must be a diplomat! Dave WA6YSO
          Message 4 of 28 , Aug 2, 2005
            Richard, you must be a diplomat!

            Dave WA6YSO

            --- In loopantennas@yahoogroups.com, Richards <jruing@a...> wrote:
            > I am a novice just studying for the first exams.... I gather you
            > guys are in agreement on one thing...
            >
            > Whether or not you fry your output transistor, having that big
            > standing wave really sucks... right?
            >
            > ///////////// Richards /////////////////
            > ===========================================
            >
            > dldorrance wrote:
            >
            > >Hank, thanks for the distinction. However, even if the wave is
            > >re-reflected (back and forth around the speed of light about
            > >
          • Richards
            Thanks... Henry... I liked that story. Kinda gets right to the heart of the sales pitch.... Are you from Missouri, ... the show me state? ...
            Message 5 of 28 , Aug 2, 2005
              Thanks... Henry... I liked that story. Kinda gets
              right to the heart of the sales pitch.... Are you from
              Missouri, ... the "show me" state? ...

              ////////////// JH Richards ////////////
              =================================

              Henry Kolesnik wrote:

              >While the rep was talking to another customer I was calling CQ on the 701 and I disconnected the antenna connector to verify what he said. He saw me doing it and tried to jump out of his skin trying to stop me, but he was too slow. He was somewhat shaken and upset and got a little testy with me but the 701 survived. I wouldn't have purchased one it didn't pass this test, and I bought one,
              >
              >
            • Richards
              WOW... THANK YOU FOR THE DETAILED REPLY. ///////// JH Richards ////////// ==================================
              Message 6 of 28 , Aug 2, 2005
                WOW... THANK YOU FOR THE DETAILED REPLY.

                ///////// JH Richards //////////
                ==================================

                vze3v8dt@... wrote:

                > Hello, Richards. Good luck with your studies.
                > In general large SWR is a bad thing, however there are things that can
                > be done to deal with it,
              • Richards
                Actually ... Worse than a diplomat.... I am a trial lawyer... (although I do not take injury cases...mostly business, criminal and divorce trial cases...)
                Message 7 of 28 , Aug 2, 2005
                  Actually ... Worse than a diplomat.... I am a trial lawyer...
                  (although I do not take injury cases...mostly business,
                  criminal and divorce trial cases...)

                  So... it is a rare instance that I play "diplomat!" Please do not
                  tell anyone in my town - they will think I have gone soft...

                  Thanks for poking some fun. //// JH Richards ///
                  ==========================================

                  dldorrance wrote:

                  >Richard, you must be a diplomat!
                  >
                  >
                  >
                  >
                • Henry Kolesnik
                  Tulsa, OK ... From: Richards To: loopantennas@yahoogroups.com Sent: Tuesday, August 02, 2005 11:10 PM Subject: Re: [loopantennas] Re: Transmitting loop
                  Message 8 of 28 , Aug 3, 2005
                    Tulsa, OK
                    ----- Original Message -----
                    From: Richards
                    To: loopantennas@yahoogroups.com
                    Sent: Tuesday, August 02, 2005 11:10 PM
                    Subject: Re: [loopantennas] Re: Transmitting loop


                    Thanks... Henry... I liked that story. Kinda gets
                    right to the heart of the sales pitch.... Are you from
                    Missouri, ... the "show me" state? ...

                    ////////////// JH Richards ////////////
                    =================================

                    Henry Kolesnik wrote:

                    >While the rep was talking to another customer I was calling CQ on the 701 and I disconnected the antenna connector to verify what he said. He saw me doing it and tried to jump out of his skin trying to stop me, but he was too slow. He was somewhat shaken and upset and got a little testy with me but the 701 survived. I wouldn't have purchased one it didn't pass this test, and I bought one,
                    >
                    >


                    If you've got links, post them in the Links section!
                    http://groups.yahoo.com/group/loopantennas/links

                    For uploading images, I prefer the Files section since Photos only allows everyone (except the uploader and moderators) to see a max of 300x400.
                    http://groups.yahoo.com/group/loopantennas/files

                    Put them in the appropriate folder, or create one.



                    ------------------------------------------------------------------------------
                    YAHOO! GROUPS LINKS

                    a.. Visit your group "loopantennas" on the web.

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                  • RICH
                    For those interested in a commercially made Transmitting Loop antenna There is one available on the e-Place. It is made by ARA and is the ARA Model MLA1/E, 1.8
                    Message 9 of 28 , Aug 6, 2005
                      For those interested in a commercially made Transmitting Loop antenna
                      There is one available on the e-Place. It is made by ARA and is the
                      ARA Model MLA1/E, 1.8 MHZ to 15 MHZ, REMOTE CONTROLLED, 1000 Watts,
                      TX&RX VERT/HORIZ Item number: 796289675.

                      There a a lot of pictures and a good description. This along with the
                      ARA Catalog description/Specifications should give you a good idea of
                      the antenna.

                      RICH WA6KNW
                    • Richard M. MC Clung
                      The item number should be: 5796289675. Some how the first 5 was eliminated the first time I sent the info..... RICH WA6KNW From: RICH
                      Message 10 of 28 , Aug 8, 2005
                        The item number should be: 5796289675. Some how the first 5 was
                        eliminated the first time I sent the info.....
                        RICH WA6KNW

                        From: "RICH" <sgm460122@...>
                        Subject: Re: Transmitting loop

                        For those interested in a commercially made Transmitting Loop
                        antenna There is one available on the e-Place. It is made by ARA and
                        is the ARA Model MLA1/E, 1.8 MHZ to 15 MHZ, REMOTE CONTROLLED, 1000
                        Watts, TX&RX VERT/HORIZ Item number: 796289675.

                        There a a lot of pictures and a good description. This along with
                        the ARA Catalog description/Specifications should give you a good
                        idea
                        of the antenna.

                        RICH WA6KNW
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