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Thread: Mobil Screwdriver Ant.

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  1. #1
    Join Date
    Jun 2004
    Location
    Park Rapids, Mn (EN27)
    Posts
    89

    Question Mobil Screwdriver Ant.

    When using a mobile screwdriver ant. can a person use a external tuner to fine tune the ant. before transmitting ?

  2. #2
    Join Date
    Jul 2001
    Location
    New Castle County, Delaware
    Posts
    7,225

    Default

    Quote Originally Posted by N0CIC View Post
    When using a mobile screwdriver ant. can a person use a external tuner to fine tune the ant. before transmitting ?
    A properly installed screwdriver antenna will be able to tune to 1:1. There is no need for an external tuner.

    My HS-1800 has no problem tuning to 1:1, even on 75m.
    "If someone tells you he believes in and talks to an invisible bunny named Harvey, you put him on medication and a regimen of therapy. If someone tells you he believes in and talks to God, well, that's perfectly acceptable. Why that's the case is impossible for me to fathom." - WP2XX

    "He's dead, Jim. You take his Tricorder and I'll get his wallet."

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  3. #3
    Join Date
    May 2001
    Location
    Roswell, NM DM73
    Posts
    2,778

    Default

    You really don't need a tuner, but any decent quality screwdriver will require some matching. The HS1800 mentioned, as do many other, has a factory supplied shunt matching coil. This is the preferred method, as once adjusted, no further adjustment is needed over the range of the antenna.

    This said, screwdrivers which cover 160 meter, usually don't need matching on 160 do to the much higher losses in the coil (several times that of an 80 meter coil).

    Built in and external tuners will extend the bandwidth of a monoband antenna, which on 160, 80, and 40 is nice to have. However, using one on a screwdriver, and forgetting to retune the antenna before switching on the tuner, can result in damaging the antenna.
    Alan Applegate, KBG
    http://www.k0bg.com

  4. #4
    Join Date
    May 2005
    Location
    belton texas
    Posts
    734

    Default

    Quote Originally Posted by N0CIC View Post
    When using a mobile screwdriver ant. can a person use a external tuner to fine tune the ant. before transmitting ?
    You can, but why? Kinda defeats the point of having a remote tuned antenna.

    A good remote tuned antenna, properly installed, can be matched very well with a shunt coil. They are pretty easy to make, and once adjusted, you don't have to fool with them anymore.

    If your antenna covers 160m, you will need a larger shunt coil to get a good match. I made my shunt coil for 160m, and tapped it for 80/40m and up.

    Operating 160m is a simple matter of unplugging the tap.
    73, Tom

  5. #5

    Default

    What type of screw driver do you plan to use? I have used a Tarheel, a Serria, a BB3 and do to going
    160m, I now have a Larry's (KJ7U 160-6) and I have NEVER used or had to use, a external turner. I have used 4 differant radios in the vehicle. I have gone to a memerizer that once the antenna is turned will
    remember that tuning location. I connect my radio coax from radio to swr mtr to memerizer to antenna and just hit the pwr switch on the radio and good to go. Try the W4RT.com and check them out.

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