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  • kb0add
    Hi, I am new to this list and have a few questions on a particular Loop Antenna. The Antenna in question is from the July, 1993 QST called Honey, I shrunk the
    Message 1 of 7 , Jan 5, 2005
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      Hi, I am new to this list and have a few questions on a particular
      Loop Antenna. The Antenna in question is from the July, 1993 QST
      called "Honey, I shrunk the Antenna" by Rod Newkirk W9BRD/VA3ZBB. I
      would like to find some one who has built this antenna and used it.

      John Kinnunen
      KB0ADD
    • Scott Erwin
      It s a variation of a magnetic loop or Magloop antenna. On 160 meters even a single turn Magloop at 10% efficiency is large. This article involves the use of
      Message 2 of 7 , Jan 6, 2005
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        It's a variation of a magnetic loop or Magloop
        antenna. On 160 meters even a single turn Magloop at
        10% efficiency is large. This article involves the use
        of capacitors on each turn in an effort to increase
        the efficiency and of a multi-turn Magloop element
        while at the same time reducing the size of it. The
        simple fact of it is this is a QST "filler" article
        used to attract non-ARRL hams to buy the magazine off
        bookstore shelves when the ARRL was still trying to
        sell there QST magazine this way. Needless to say they
        no longer provide QST for sell in this way, as it was
        a money loser. This antenna "might" work at 1%
        efficiency. A 100-watt light bulb would most likely
        provide more contacts. I build and use Magloop
        antennas so I know what to expect. Just building a
        single element Magloop involves using silver solder on
        all copper connections or welding joints on aluminum
        connections and none of this is done at all in this
        article. This article should have shown up in the
        April, 1993 QST.
        --- kb0add <kb0add@...> wrote:

        >
        >
        > Hi, I am new to this list and have a few questions
        > on a particular
        > Loop Antenna. The Antenna in question is from the
        > July, 1993 QST
        > called "Honey, I shrunk the Antenna" by Rod Newkirk
        > W9BRD/VA3ZBB. I
        > would like to find some one who has built this
        > antenna and used it.
        >
        > John Kinnunen
        > KB0ADD
        >
        >
        >
        >
        >
        >
        >




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      • John Kinnunen
        Hi Scott, WHAT is this????? The Blind trying to lead the Blind????? You should open your eyes and see what is out there. Your comments suggest that the only
        Message 3 of 7 , Jan 6, 2005
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          Hi Scott,

          WHAT is this????? The Blind trying to lead the
          Blind????? You should open your eyes and see what is
          out there. Your comments suggest that the only way for
          me to get anything to work is to go with a Purists
          Ideals. With this thought in mind, you might say that
          no one would get out of the back yard unless there 80
          meter dipole is up over 67 feet. I wonder how many
          contacts you have made on 80 meters with other hams
          who have there 80 meter Antennas way under that
          hight?????

          Purity of Theory is good but NOT PRACTICAL. I am NOT a
          Theorist I am a very practical person who wants to see
          how much fun one can have with the prevailing
          conditions. If that means having that 80 meter antenna
          only 15 feet above the ground, SO BE IT.

          The Article in Question HAS Merit!!!!!!!!!!!! Whether
          or not it was written for the purpose you state has NO
          barring on the article itself. TAKE YOUR VENDETTA UP
          WITH QST NOT ME.

          I am looking for Practical information and not some
          very NON-practical theories. But thanks for you
          interest anyway.

          John Kinnunen
          KB0ADD




          --- Scott Erwin <n4zou@...> wrote:

          > It's a variation of a magnetic loop or Magloop
          > antenna. On 160 meters even a single turn Magloop at
          > 10% efficiency is large. This article involves the
          > use
          > of capacitors on each turn in an effort to increase
          > the efficiency and of a multi-turn Magloop element
          > while at the same time reducing the size of it. The
          > simple fact of it is this is a QST "filler" article
          > used to attract non-ARRL hams to buy the magazine
          > off
          > bookstore shelves when the ARRL was still trying to
          > sell there QST magazine this way. Needless to say
          > they
          > no longer provide QST for sell in this way, as it
          > was
          > a money loser. This antenna "might" work at 1%
          > efficiency. A 100-watt light bulb would most likely
          > provide more contacts. I build and use Magloop
          > antennas so I know what to expect. Just building a
          > single element Magloop involves using silver solder
          > on
          > all copper connections or welding joints on aluminum
          > connections and none of this is done at all in this
          > article. This article should have shown up in the
          > April, 1993 QST.
          > --- kb0add <kb0add@...> wrote:
          >
          > >
          > >
          > > Hi, I am new to this list and have a few questions
          > > on a particular
          > > Loop Antenna. The Antenna in question is from the
          > > July, 1993 QST
          > > called "Honey, I shrunk the Antenna" by Rod
          > Newkirk
          > > W9BRD/VA3ZBB. I
          > > would like to find some one who has built this
          > > antenna and used it.
          > >
          > > John Kinnunen
          > > KB0ADD
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          >
          >
          >
          >
          > __________________________________
          > Do you Yahoo!?
          > Yahoo! Mail - now with 250MB free storage. Learn
          > more.
          > http://info.mail.yahoo.com/mail_250
          >



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        • Scott Erwin
          I currently run a Magloop for 20 and 40 meters using a single turn element made of 20 feet of 3/4 inch copper plumbing pipe. I use a homebrew copper butterfly
          Message 4 of 7 , Jan 6, 2005
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            I currently run a Magloop for 20 and 40 meters using a
            single turn element made of 20 feet of 3/4 inch copper
            plumbing pipe. I use a homebrew copper butterfly
            capacitor rated at 12,000 volts and is 10-pF to 100-pF
            capacitance. The efficiency on 20 meters is 91.2
            percent compared to a 20 meter dipole at 1/2
            wavelength above ground and on 40 meters it's
            efficiency is 45.7 percent also compared to a 40 meter
            dipole at 1/2 wavelength above ground using KI6GD
            Magnetic loop antenna calculator V 1.6 software. This
            is calculated with a Magloop operated 6 inches above
            an aluminum ground screen to prevent earth loss. The
            aluminum ground screen in my case is a small aluminum
            camper roof. Actual operation shows that on 20 and 40
            meters a high dipole is slightly better in some
            instances than the Magloop and in other cases the
            Magloop will outperform the dipole. The advantage is
            that the Magloop is easy and fast to setup where as
            the dipole takes time to install in trees or other
            supports and in some instances may not be allowed in
            the parking lot of a disaster shelter or other areas
            where you might need to operate. What you need to do
            is research magnetic loop operation and design and
            form your own opinion. Here are some good links to get
            you started.
            http://www.laud.no/la6nca/loop/
            http://www.geocities.com/gw0tqm/magloop/magloop.htm
            http://www.standpipe.com/w2bri/index.htm
            http://www.ve3gk.com/newmagnetic.htm
            http://www.binkhorst.org/html/compact_magnetic_loop.php
            http://homepage.ntlworld.com/bill.g4kki/radio.html
            http://www.iri.tudelft.nl/~geurink/magnloop.htm
            To get the best performance from small Magloop
            antennas built with copper plumbing pipe and used with
            45 and 90-degree fittings is to apply a silver-plating
            across the joints. You don't need or even want to
            silver plate the entire element, just at the point
            where the joints overlap. A good and cheap way to do
            this is with a Caswell Inc. Plug N' Plate
            silver-plating kit. The link is
            http://www.caswellplating.com/kits/plugnplate.htm
            Now as for as having a VENDETTA with QST, I do not
            have one with them. I simply stated a fact that at
            times in the past some articles published in QST did
            not achieve a quality level that some think that all
            articles published in QST must be. Like any other
            magazine some information published will slip through
            that was for doing something other than providing a
            successful project to be built. If you download some
            of the Magloop calculation programs and punch in the
            numbers you find out just how bad that antenna would
            be. I am just trying to give you some good information
            so you can build a Magloop antenna that will actually
            work, and work well.

            --- John Kinnunen <kb0add@...> wrote:

            > Hi Scott,
            >
            > WHAT is this????? The Blind trying to lead the
            > Blind????? You should open your eyes and see what
            > is
            > out there. Your comments suggest that the only way
            > for
            > me to get anything to work is to go with a Purists
            > Ideals. With this thought in mind, you might say
            > that
            > no one would get out of the back yard unless there
            > 80
            > meter dipole is up over 67 feet. I wonder how many
            > contacts you have made on 80 meters with other hams
            > who have there 80 meter Antennas way under that
            > hight?????
            >
            > Purity of Theory is good but NOT PRACTICAL. I am NOT
            > a
            > Theorist I am a very practical person who wants to
            > see
            > how much fun one can have with the prevailing
            > conditions. If that means having that 80 meter
            > antenna
            > only 15 feet above the ground, SO BE IT.
            >
            > The Article in Question HAS Merit!!!!!!!!!!!!
            > Whether
            > or not it was written for the purpose you state has
            > NO
            > barring on the article itself. TAKE YOUR VENDETTA UP
            > WITH QST NOT ME.
            >
            > I am looking for Practical information and not some
            > very NON-practical theories. But thanks for you
            > interest anyway.
            >
            > John Kinnunen
            > KB0ADD
            >
            >
            >
            >
            > --- Scott Erwin <n4zou@...> wrote:
            >
            > > It's a variation of a magnetic loop or Magloop
            > > antenna. On 160 meters even a single turn Magloop
            > at
            > > 10% efficiency is large. This article involves the
            > > use
            > > of capacitors on each turn in an effort to
            > increase
            > > the efficiency and of a multi-turn Magloop element
            > > while at the same time reducing the size of it.
            > The
            > > simple fact of it is this is a QST "filler"
            > article
            > > used to attract non-ARRL hams to buy the magazine
            > > off
            > > bookstore shelves when the ARRL was still trying
            > to
            > > sell there QST magazine this way. Needless to say
            > > they
            > > no longer provide QST for sell in this way, as it
            > > was
            > > a money loser. This antenna "might" work at 1%
            > > efficiency. A 100-watt light bulb would most
            > likely
            > > provide more contacts. I build and use Magloop
            > > antennas so I know what to expect. Just building a
            > > single element Magloop involves using silver
            > solder
            > > on
            > > all copper connections or welding joints on
            > aluminum
            > > connections and none of this is done at all in
            > this
            > > article. This article should have shown up in the
            > > April, 1993 QST.
            > > --- kb0add <kb0add@...> wrote:
            > >
            > > >
            > > >
            > > > Hi, I am new to this list and have a few
            > questions
            > > > on a particular
            > > > Loop Antenna. The Antenna in question is from
            > the
            > > > July, 1993 QST
            > > > called "Honey, I shrunk the Antenna" by Rod
            > > Newkirk
            > > > W9BRD/VA3ZBB. I
            > > > would like to find some one who has built this
            > > > antenna and used it.
            > > >
            > > > John Kinnunen
            > > > KB0ADD
            > > >
            > > >
            > > >
            > > >
            > > >
            > > >
            > > >
            > >
            > >
            > >
            > >
            > > __________________________________
            > > Do you Yahoo!?
            > > Yahoo! Mail - now with 250MB free storage. Learn
            > > more.
            > > http://info.mail.yahoo.com/mail_250
            > >
            >
            >
            >
            > __________________________________
            > Do you Yahoo!?
            > Meet the all-new My Yahoo! - Try it today!
            > http://my.yahoo.com
            >
            >
            >


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          • Jim Dunstan
            ... Hi: I found the description of your Magloop very interesting. I operate from 2 very different QTH s; one is more or less traditional with a tower and
            Message 5 of 7 , Jan 6, 2005
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              At 05:33 PM 1/6/05 -0800, you wrote:
              I currently run a Magloop for 20 and 40 meters using a
              single turn element made of 20 feet of 3/4 inch copper
              plumbing pipe. I use a homebrew copper butterfly
              capacitor rated at 12,000 volts and is 10-pF to 100-pF
              capacitance. The efficiency on 20 meters is 91.2
              percent compared to a 20 meter dipole at 1/2
              wavelength above ground and on 40 meters it's
              efficiency is 45.7 percent also compared to a 40 meter
              dipole at 1/2 wavelength above ground using KI6GD
              Magnetic loop antenna calculator V 1.6 software. This
              is calculated with a Magloop operated 6 inches above
              an aluminum ground screen to prevent earth loss.

              Hi:

              I found the description of your Magloop very interesting.  I operate from 2 very different QTH's;  one is more or less traditional with a tower and rotatable dipole up about 50' (Thunder Bay) while the other is less so being in a 9th flr apartment (Toronto).  I have 2 balconies to work from and settled on a bent wire dipole (20M) held out over the balcony railing.  I feed it with open wire line and have great success with it on both 20 es 15 M.

              However I miss 40M operation.  I have a simple Magloop software program and ran your dimensions and find approximately the same results you did; 20F of 3/4" copper producing about 45% efficiency.  The diameter would be about 6', about the maximum size I could accommodate on my second balcony.  I have experimented with loaded dipoles (12' end to end)... eg like a couple of hamstick mobile type antennas.  I have not been able to accurately measure efficiency of this antenna but I am certain it is less than 45%.  A 6' dia. loop might be easier to deal with.

              I would use the loop for 40M only ... Have you tried orienting the loop horizontally?  I have been considering this since the area in which I would mount the loop is surrounded on 3 sides by a 3' metal guard railing.  I assume you feed your loop with a small coax loop.  I would have to keep the power down since I have not found anything like your 12,000 V capacitor.  I use a kenwood TS-50s in the apartment shack which runs 3 power levels 10, 50, 100.  I would certainly like to use the 50W setting but would need a capacitor with at least 6000 V rating.

              I also assume you cut the pipe into 8 equal length (approx. 2 1/2') pieces and used 45 deg elbows.  It sounds like it might be a fun project out on the balcony hi hi ..

              Another possible antenna might be one of those strange high capacitance low inductance models.  As with the magloop it is also a mechanical construction job .... instead of plumbing one needs to have some sheet metal fabrication skills hi hi.  This antenna apparently also boasts high efficiency for small size.  However, it has the added advantage of near immunity to close metal objects.  Sounds a little space age hi hi ..

              Hmmm what one won't do to get on 40M!  vive 40


               

              Jim Dunstan, VE3CI
              Thunder Bay, ON

            • Scott Erwin
              I only used one T copper pipefitting, which connected the two, 10-foot long sections of 3/4 inch copper pipe. I used a conduit bender to form the loop and
              Message 6 of 7 , Jan 7, 2005
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                I only used one "T" copper pipefitting, which
                connected the two, 10-foot long sections of 3/4 inch
                copper pipe. I used a conduit bender to form the loop
                and used 22-degree (+ or -) angles for a total of 16
                bends. This is closer to a circle and hence the
                efficiency is increased slightly. The reason for this
                is the 22 or 23-degree angles are much easier to
                obtain than a 45-degree bend on the copper pipe and
                there are no fittings to buy and solder and less
                chance for a bad solder job. The only joint is for the
                "T" which does two jobs. One is to connect the two
                lengths of pipe and two is making available a place
                for the motor power wires run inside the pipe to have
                a nice place to exit the pipe. Having been an
                electrician it was easy for me to bend the pipe. If
                you can find a local ham with a pipe bender to help
                you out if you do it this way it will save you a lot
                of time and money as you wont need to buy a bender and
                you wont need to buy some cheap 3/4 inch EMT conduit
                to practice on. I made my capacitor by hand. All you
                need is a set of aviation snips to cut the copper
                sheet metal, a drill press, and some construction
                paper to use as patterns for the stator and rotor
                plates. You can practice on some cheap aluminum sheet
                from a building supply store for roofing use. Once you
                get used to cutting the sheet aluminum you can move to
                the copper sheet. It's fun to work with and soon you
                will be making your own project boxes from copper!
                Polished and coated with clear paint your projects
                will impress anyone, ham or not! While I was
                recovering from some surgery I wrote and article on
                how I made my capacitor. The link is
                http://www.eham.net/articles/9527
                Also follow the link to the ON4CEQ site at
                http://www.qsl.net/mnqrp/Loop/Mag_Loops.htm
                for some great information on construction on Magloop
                antennas.
                If your only going to use the Magloop on a single band
                your capacitor can be a section of RG-8 coax cut to a
                length that will provide a 1:1 SWR match at your
                frequency of choice.
                The Magloop will couple to any metal objects close it.
                If you can elevate it above any surrounding metal
                objects it will help out a lot. You can also improve
                it by placing a ground under it. This can be in the
                form of radial wires or sheet aluminum. It only needs
                to cover the same area of the loop. If you have a
                6-foot loop then 6-foot radial wires will work fine as
                would something like a 4 by 8 foot sheet of aluminum.
                You can allow the ground screen to be connected at
                center of the loop at the feed point, which is a
                neutral point, or just allow it to float at RF under
                it. This keeps the loop from coupling to the earth
                below it. I use the aluminum roof of my Magloop for
                this. As for performance the 20-foot Magloop beats a
                40-meter mobile vertical antenna hands down.

                --- Jim Dunstan <jimdunstan@...> wrote:

                > At 05:33 PM 1/6/05 -0800, you wrote:
                > >I currently run a Magloop for 20 and 40 meters
                > using a
                > >single turn element made of 20 feet of 3/4 inch
                > copper
                > >plumbing pipe. I use a homebrew copper butterfly
                > >capacitor rated at 12,000 volts and is 10-pF to
                > 100-pF
                > >capacitance. The efficiency on 20 meters is 91.2
                > >percent compared to a 20 meter dipole at 1/2
                > >wavelength above ground and on 40 meters it's
                > >efficiency is 45.7 percent also compared to a 40
                > meter
                > >dipole at 1/2 wavelength above ground using KI6GD
                > >Magnetic loop antenna calculator V 1.6 software.
                > This
                > >is calculated with a Magloop operated 6 inches
                > above
                > >an aluminum ground screen to prevent earth loss.
                >
                > Hi:
                >
                > I found the description of your Magloop very
                > interesting. I operate from 2
                > very different QTH's; one is more or less
                > traditional with a tower and
                > rotatable dipole up about 50' (Thunder Bay) while
                > the other is less so
                > being in a 9th flr apartment (Toronto). I have 2
                > balconies to work from
                > and settled on a bent wire dipole (20M) held out
                > over the balcony
                > railing. I feed it with open wire line and have
                > great success with it on
                > both 20 es 15 M.
                >
                > However I miss 40M operation. I have a simple
                > Magloop software program and
                > ran your dimensions and find approximately the same
                > results you did; 20F of
                > 3/4" copper producing about 45% efficiency. The
                > diameter would be about
                > 6', about the maximum size I could accommodate on my
                > second balcony. I
                > have experimented with loaded dipoles (12' end to
                > end)... eg like a couple
                > of hamstick mobile type antennas. I have not been
                > able to accurately
                > measure efficiency of this antenna but I am certain
                > it is less than 45%. A
                > 6' dia. loop might be easier to deal with.
                >
                > I would use the loop for 40M only ... Have you tried
                > orienting the loop
                > horizontally? I have been considering this since
                > the area in which I would
                > mount the loop is surrounded on 3 sides by a 3'
                > metal guard railing. I
                > assume you feed your loop with a small coax loop. I
                > would have to keep the
                > power down since I have not found anything like your
                > 12,000 V capacitor. I
                > use a kenwood TS-50s in the apartment shack which
                > runs 3 power levels 10,
                > 50, 100. I would certainly like to use the 50W
                > setting but would need a
                > capacitor with at least 6000 V rating.
                >
                > I also assume you cut the pipe into 8 equal length
                > (approx. 2 1/2') pieces
                > and used 45 deg elbows. It sounds like it might be
                > a fun project out on
                > the balcony hi hi ..
                >
                > Another possible antenna might be one of those
                > strange high capacitance low
                > inductance models. As with the magloop it is also a
                > mechanical
                > construction job .... instead of plumbing one needs
                > to have some sheet
                > metal fabrication skills hi hi. This antenna
                > apparently also boasts high
                > efficiency for small size. However, it has the
                > added advantage of near
                > immunity to close metal objects. Sounds a little
                > space age hi hi ..
                >
                > Hmmm what one won't do to get on 40M! vive 40
                >
                >
                >
                >
                > Jim Dunstan, VE3CI
                > Thunder Bay, ON


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              • Jim Dunstan
                ... That is a good idea. It never occurred to me to simply bend two 10 pieces of rigid pipe to make 2 halfs of a loop. I don t have any of the equipment you
                Message 7 of 7 , Jan 8, 2005
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                  At 07:52 AM 1/7/05 -0800, you wrote:
                  I only used one "T" copper pipefitting, which
                  connected the two, 10-foot long sections of 3/4 inch
                  copper pipe. I used a conduit bender to form the loop
                  and used 22-degree (+ or -) angles for a total of 16
                  bends. This is closer to a circle and hence the
                  efficiency is increased slightly. The reason for this
                  is the 22 or 23-degree angles are much easier to
                  obtain than a 45-degree bend on the copper pipe and
                  there are no fittings to buy and solder and less
                  chance for a bad solder job. The only joint is for the
                  "T" which does two jobs. One is to connect the two
                  lengths of pipe and two is making available a place
                  for the motor power wires run inside the pipe to have
                  a nice place to exit the pipe. Having been an
                  electrician it was easy for me to bend the pipe. If
                  you can find a local ham with a pipe bender to help
                  you out if you do it this way it will save you a lot
                  of time and money as you wont need to buy a bender and
                  you wont need to buy some cheap 3/4 inch EMT conduit
                  to practice on.                   

                  That is a good idea.  It never occurred to me to simply bend two 10' pieces of rigid pipe to make 2 halfs of a loop.  I don't have any of the equipment you mentioned, but I am retired from the local community college and i can go over to the shop and get them bent for me no problem .... a retirement fringe benefit.  When I get them up to the apartment balcony I will just have to solder the Tee joint.  I will invent some sort of frame to mount the loop and the tuning capacitor.  At this time I don't think I am going to undertake the manufacture of a high voltage tuning capacitor ... however, the fixed tuned idea using trimmed coax might be a starting point.  I am active on psk which doesn't need a lot of QSYing.

                  Tnx ... Jim

                  Jim Dunstan, VE3CI
                  Thunder Bay, ON

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