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20 meter 'no radials' vertical antenna made from "Satellite TV" co-ax.

Discussion in 'Home Brew' started by ButtFuzz, Oct 21, 2015.

  1. ButtFuzz

    ButtFuzz
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    Anti-BS Advocate ● N4REV ● Reverend Doctor

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    subtitled: The DirecTV OMG! Antenna.
    I got the idea for this build while searching for tips on a "pipe 'n' co-ax" Zepp antenna.
    CLICK HERE for the general idea behind this antenna.

    A few years ago, my friend Andy moved into a new house and wanted all the external, "ugly" co-ax removed from the domicile. I obliged. It sat on a shelf in the basement until a little while ago. Here is is:
    [​IMG]

    This co-ax is the "outdoor feed" installed by many Satellite TV installers, and has a good, solid ground wire bonded to the side of the co-ax. This gave me an idea to build a vertical Zepp using only the coax. Here's that the end of the wires look like:
    [​IMG]
    See that ground wire affixed to the co-ax? That's good!!!

    We need to calculate the length of one leg of a 1/2 wave dipole for 20 meters. The formula for this (copper wire) is length in feet = 234 divided by the frequency in megahertz. Or you could simply use an online calculator like I do. HERE's ONE! Since I am an EXTRA class CB'er, I chose the lower end of the 20 meter phone sub-band as my cutting frequency, which is 14.150 MHz. This came out to 16' 6-3/8". So I made it a little long (I will be using a tuner... see 'notes') and cut the coax.
    [​IMG]
    After cutting the co-ax, I had a tidy amount left over... perhaps a 40 meter vertical is next?
    [​IMG]

    Next thing to do is to prepare the "far end" of the cut piece of co-ax. The 'far end' is opposite the feed point, and is the end of the co-ax that you will be hoisting up into the tree or other support. Carefully prepare the "far end"... take your time and cut carefully... make it look like this:
    [​IMG]

    Now TIN the far end. DO NOT use a 100w Space-Ray soldering iron or you will melt the whole affair. Weatherproof the parts shown, then bend the wire, carefully, to look something like this:
    [​IMG]



    Solder the wires together and add more weatherproofing. AGAIN: DO NOT use excessive heat. You should end up with something like this:
    [​IMG]

    Attach a small leader of 130 pound test braided Dacron fishing line to the far end, then weatherproof the whole affair. This will be the end you hoist up into the tree or other support, and you can hitch the fishing line to your pull line.
    [​IMG]
    In the picture above, the Dacron line is shown coming out of the end of the shrink tube for clarity.

    Here's the "feed point":
    [​IMG]
    Attach your feedline by whatever means necessary to the coax (see 'notes'). The ground wire I have terminated in red shrink tube. You will use this as your 'tuning stub', as it really is the end of 1/2 of your 'stealth vertical dipole.'

    Read the notes, below, and if you are still confused, send a message to ButFuzz.

    Notes:
    This antenna uses "Satellite TV" co-ax that appears to have no ground plane and defies the laws of physics.

    But it doesn't, really.

    It is best described as an end-fed vertical Zepp made from 'specialty' co-ax cable.

    Yes, this is nominally 75 Ohm Coax.
    Since one will likely be using a tuner with this antenna, it won't matter too much.

    Yes, the end connector is an "F" connector. Buy an adapter, chop it off and replace with PL-259, or chop it off and feed it with 300 ohm twin lead. It's your thing! Do whatcha' wanna do!

    Yes, it was lots easier hoisting this thing up into a tree than a center-fed dipole. And it fits in my trunk for "remote" work a lot easier, too.

    I hope you had as much fun building this antenna as I did. It works. Next up? 40 meter vertical!

    Take care,
    Rob
     
    #1 ButtFuzz, Oct 21, 2015
    Last edited: Oct 21, 2015

  2. ButtFuzz

    ButtFuzz
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    Anti-BS Advocate ● N4REV ● Reverend Doctor

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    Although I have not tried it... this particular build should work acceptably on 6 meters, too... especially with a tuner.
     
  3. wavrider

    wavrider
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    W9WDX Amateur Radio Club Member

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    Looking good ButtFuzz, Let us know how it performs for you.
     

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