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CB dedicated dipole?? Half or Full Wave?

Discussion in 'CB Antennas' started by PA770, Aug 4, 2018.

  1. PA770

    PA770 W9WDX Member

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    I can mount the 1:1 center balun at 20' exactly on a pole and bring the ends down into an inverted V to the ends.. then ends would tie off just at the roof edge of my mobile home with insulators.

    I can do either a half wave or fullwave..

    Which should I do? Would I gain anything with a full wave?

    I was going to get an A99 and the proposed Imax 2000 seems too tall for my HOA mobile home park..

    Hence the 1:1 balun wouldn't stick out as much..



    I am using real Times LMR-240 about 29' of it..
     
    AmericanEagle575 likes this.

  2. sp5it

    sp5it Master of puppets

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    Fullwave dipole... Tell me more.
     
    RatsoW8 likes this.
  3. Riverman71

    Riverman71 Sr. Member

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  4. PA770

    PA770 W9WDX Member

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  5. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    A full wave dipole would have an impedance of many hundreds if not thousands of ohms driving your SWR to near infinity with some sort or matching device and the minute gain from using one would be minuscule. Go with a half wave.
     
  6. PA770

    PA770 W9WDX Member

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    So from reading Abit.. would an inverted V with peak at 20' work about the same as an A99 at least??
     
  7. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    Are you hanging the V vertically? If you hang it normally it will be horizontally polarized and will not be great for local talking.
     
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  8. PA770

    PA770 W9WDX Member

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    Inverted V with ends lower.. center at 20' and ends at 13'..
     
  9. 543_Dallas

    543_Dallas Sr. Member

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    The full wave has gain over the 1/2 wave. The trick to making the full wave work is feeding it with a 1/4 wavelength of ladder line. 450 ohm window line will work. Then use your balun / common mode choke to connect the coax to the ladder line.

    The 1/4 wavelength of ladder line will transform the high impedance of the full wave dipole (pair of half waves in phase) to a low impedance you can work with. Hams did this kind of stuff before modern appliances and store bought dipoles so it's kind of like black magic today.

    If you can stretch it out to 5/8 wave per leg you have an extended double zepp with more gain.
     
  10. 543_Dallas

    543_Dallas Sr. Member

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  11. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    And back when hams did that kind of stuff transmitters had tube finals and would work into weird impedances rather well. Try that with a solid state final and see how high the SWR is and how well it works. I understand where you are coming from but with no offense to K3ACV if he has to ask these questions he is no where ready to start dealing with balanced feedlines as impedance transformers and baluns and transmatches etc. For simplicity sakes and the extreme minimal difference I suggest he get started with the simple halfwave dipole.
     
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  12. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    That's all I used for several years. An 80m doublet fed with 450 ohm ladderline to a remote auto-tuner thru a 1:1 balun. It worked quite well especially on 80,40, and 20m. Never tried it too much on the higher bands as propagation sucked on them at the time. Even earlier I used an 80m inverted V with 450 ohm ladder line straight into the shack then thru a tuner with a builtin balun. I worked a lot of DX with the little Heath DX-60B with that.
     
    The DB likes this.
  13. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    It will be good for distance but lousy for local
     
    357magnum likes this.
  14. 543_Dallas

    543_Dallas Sr. Member

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    I have tried that with modern gear and it works great. You don't even need a tuner for a single band. A simple coax choke where the ladder line meets the coax works fine. No special balun is needed.

    Im not talking about working into a weird impedance. It takes some trimming of the ladder line and antenna but the point where the coax connects to the ladder line will be around 50 ohms and the vswr will be as good as your patience allows. The modern rigs never know the difference. Just because most of us don't have transmitters with link coupled finals doesn't mean we can't use this stuff.

    I do agree that starting with a simple coax fed dipole is probably best. At least we can plant ideas that may be useful to him in the future instead of just telling him it won't work. Teach a man to fish.
     
  15. PA770

    PA770 W9WDX Member

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    So try and get the A99 at the least is what your saying, and put the tip at about 38'.. the feeepoint would be about 19'..
     

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