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RE: [HARC] Antenna Tuners

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  • Dave Posthuma
    I built the LDG automatic tuner and it works wonders! I can highly recommend it for power levels up to 150 watts. I can always get an SWR down to 1.2:1 or
    Message 1 of 4 , Mar 6, 2001
      I built the LDG automatic tuner and it works wonders! I can highly
      recommend it for power levels up to 150 watts. I can always get an SWR down
      to 1.2:1 or less with very low insertion loss...after all, I am almost
      always QRP.

      David Posthuma, WD8PUO

      -----Original Message-----
      From: manager@... [mailto:manager@...]
      Sent: Tuesday, March 06, 2001 12:13 PM
      To: k8daa@yahoogroups.com
      Subject: [HARC] Antenna Tuners

      Scott,

      I have been using both options Automatic and Manual tuners for
      years. Here is my input.

      Avoid a tuner when ever possible, always try to adjust your antenna
      for proper resonance and SWR
      without the use of any tuner, this is the most efficient antenna
      system around.

      If you intend to use your tuner while Mobile, an Automatic Tuner is
      the way to go for obvious reasons
      however with my experience I've noticed some limitations of
      autotuners in that they sometimes have a
      problem of getting the SWR below 2:1, not that its a big deal, but
      personally I'd rather have below
      1.5:1 because most newer rigs will cut the power back at anything
      above 2:1, and its just to close
      to call.

      For home use, the manual tuner with balun is the way to go (not that
      I would recommend a MFJ) but
      with a manual tuner, you have much greater flexibility, as I say you
      can load a BED SPRING if you want
      to, and get on the air. For my home, I use a DENTRON M-3000 Tuner,
      this is a rare tuner, but if you find
      one, BUY IT, no questions asked, it will handle 3 kW easy, it will
      load just about anything INCLUDING a
      BED SPRING, and it also has features such as 200 W Dummy Load built-
      in, 4:1 balun built-in for long wires
      and a wide range of inductor, capacitance for tuning.

      In most cases, once you have determined your tuner settings for each
      band (I keep a chart) you know about
      where the tuner needs to be set for each band of operation, once your
      in the range, a little bump on this knob, alittle bump on that knob,
      and your on the air.

      Tuners are nice, but remember they only server one purpose, TRICK the
      Transmitter into thinking its seeing
      a true 50 ohm load, regardless of the antenna, to eliminate the
      radios finals from overheating, and burning out.
      So even though you might have that 12 meter whip, on 160 meters, its
      like a needle in a hay stack compared to a truly resonant antenna for
      160, and for any other band for that matter. The same ole principle
      always holds true, the MORE WIRE, the BIGGER the NET for CATCHING
      that rare DX or STATION.

      Good luck with whatever your choice.


      Robert Underwood, Manager
      Wolverine Power Systems, Inc.


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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 2 of 4 , Mar 7, 2001
        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 3 of 4 , Mar 7, 2001
          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 4 of 4 , Mar 7, 2001
            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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