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RE: [HARC] Antenna Tuners

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  • scott.a.hansen@jci.com
    Thanks Dave, Which model of the LDG did you build. I can only do 100 watts. Although Jim Lambert tells me thats only a temporary infliction. I do, however,
    Message 1 of 4 , Mar 7, 2001
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      Thanks Dave,
      Which model of the LDG did you build. I can only do 100 watts. Although
      Jim Lambert tells me thats only a temporary infliction. I do, however,
      plan on sticking with the 100 watt output for some time. As I type and
      think, I am wondering what bands you are tuning up on and what antennas you
      are using?
      Thanks,
      Scott
    • Dave Posthuma
      Scott: I built the AT-11MP (the one with the cross-needles). I use 80 - 10 meters and have been able to take any antenna combination and load for any band
      Message 2 of 4 , Mar 7, 2001
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        Scott:
        I built the AT-11MP (the one with the cross-needles). I use 80 - 10 meters
        and have been able to take any antenna combination and load for any band
        combination with 1.2:1 or less. I do not currently have 160 meters on my K2
        and so have not had an opportunity to try loading 160. However, it is my
        understanding from talking with other Hams that use the LDG tuner that they
        have had good success on both 160 and even 6 meters if the antenna impedance
        is not too extreme. I am very happy with the LDG. The kit version went
        together very well and operated first-try without a problem. I would never
        go back to a manual tuner. The one condition is that you must be able to
        power down your rig to 10 watts or less while tuning or else be very
        confident in your rig's SWR protection system. I always power down to about
        6 watts. The LDG also functions as a relative watt meter. It also has an
        optional remote control unit for mobile operation, and an interface
        capability with the Icom 706 and I also believe the Alinco.

        My LDG has tuned any antenna in 3 seconds or less. I do not use the 4:1
        balun option currently. I am not a fan of long-wire antennas because the
        feed point is the primary radiation point. Unless the long-wire/tuner
        combination is mounted out of the shack and on the tower, you will be
        exposing yourself to high levels of radiation and your radiation pattern
        will likely be quite poor. It is always best to use a tuned antenna. The
        only exception for where the balun may be helpful, is if you want to use
        ladder-line and a tuned 80 or 160 meter dipole (or G5RV feed only with
        ladder-line) for multi-band operation. This form of multi-banding is very
        common. (I would not coax feed a G5RV in conjunction with a tuner. ARRL
        analysis of this configuration has demonstrated that while the antenna may
        be tunable, there is considerable feed-line loss resulting in the majority
        of your wattage being turned into heat within the feed line and not in
        reality radiating.)

        My last suggestion is that if you do make use of an automatic antenna tuner,
        it would be wise to use 1:1 RF baluns (easily made by coiling your coax at
        the shack and antenna points). Without the Coax baluns, stray RF can run
        down the outside of the coax shield, to the antenna tuner, and can cause the
        tuner to mis-read the actual SWR.

        I hope this helps. If you want to come over some time and see my tuner in
        action, you're welcome to do so.

        David Posthuma, WD8PUO

        -----Original Message-----
        From: scott.a.hansen@... [mailto:scott.a.hansen@...]
        Sent: Wednesday, March 07, 2001 7:51 AM
        To: k8daa@yahoogroups.com
        Subject: RE: [HARC] Antenna Tuners

        Thanks Dave,
        Which model of the LDG did you build. I can only do 100 watts. Although
        Jim Lambert tells me thats only a temporary infliction. I do, however,
        plan on sticking with the 100 watt output for some time. As I type and
        think, I am wondering what bands you are tuning up on and what antennas you
        are using?
        Thanks,
        Scott


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      • scott.a.hansen@jci.com
        Thanks for the nice write up Dave, I called LDG and there is an interface cable that works with my radio. It allows one button tuning. All I would need to do
        Message 3 of 4 , Mar 7, 2001
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          Thanks for the nice write up Dave,
          I called LDG and there is an interface cable that works with my radio. It
          allows one button tuning. All I would need to do is push the tune button
          on my radio, it will send a low power CW signal to the tuner and it will
          make the adjustments. When it finishes, it sends a signal back to the
          radio and the controls return to normal operation. Each time you change
          bands or frequencies significantly, just push the button.
          This is why the autotuner sounds so attractive. The kit idea sounds like
          fun as well.
          I still need to think about this some more, but the LDG sounds like a
          pretty good way to go.
          Any more thoughts on this will be appreciated.
          Thanks,
          Scott
          I am currently using a 102' center fed "dipole" ( I guess it's a form of a
          non-resonant dipole?) fed with a 300 Ohm twin lead into a 4:1 balun at my
          MFJ 949C manual tuner. It works OK. The tuner will match 10-80 meters
          very well. 160 gives me fits. I just don't have a big enough lot!
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