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Thread: FM transmitter antenna

  1. #46
    Stay-Puft! rcktpwrd's Avatar
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    Default Re: FM transmitter antenna

    I have a couple pics of the connector and the wires attached, it was too difficult to get a picture of the entire antenna. No pics of it installed in the 'attic' space...

    https://goo.gl/photos/asWjmVCqWam2YfJv5

    https://goo.gl/photos/L4vXamyT3DMRsR8VA
    Joel


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    Havin fun ! kidcole's Avatar
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    Default Re: FM transmitter antenna

    Quote Originally Posted by rcktpwrd View Post
    I have a couple pics of the connector and the wires attached, it was too difficult to get a picture of the entire antenna. No pics of it installed in the 'attic' space...

    https://goo.gl/photos/asWjmVCqWam2YfJv5

    https://goo.gl/photos/L4vXamyT3DMRsR8VA
    Gorgeous ! I am not an expert on the design of FM devices. But from what I've read about DIY antennas, you'll get a better result if the bottom 4 ground reflection wires are perfectly straight (or as close as you can get them) and exact same length from the mounting screws. Also the angle of each wire being as precise as you can get them .. 90 degrees off each other (pointing out the corners) and all with same ground angle. I use a large builders framing square with a level to check mine each time I put it out. The tiniest of imperfections add to degrading the wave that flows off the vertical wire.

    If it's not too much trouble next February, I'd love to get you to demo that antenna at next year's first TASL meeting ! Those DIY quarter wave antennas are easily as good as the commercial ones...
    Thanks,

    Denny Cole
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  3. #48
    Stay-Puft! rcktpwrd's Avatar
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    Default Re: FM transmitter antenna

    Quote Originally Posted by kidcole View Post
    Gorgeous ! I am not an expert on the design of FM devices. But from what I've read about DIY antennas, you'll get a better result if the bottom 4 ground reflection wires are perfectly straight (or as close as you can get them) and exact same length from the mounting screws. Also the angle of each wire being as precise as you can get them .. 90 degrees off each other (pointing out the corners) and all with same ground angle. I use a large builders framing square with a level to check mine each time I put it out. The tiniest of imperfections add to degrading the wave that flows off the vertical wire.

    If it's not too much trouble next February, I'd love to get you to demo that antenna at next year's first TASL meeting ! Those DIY quarter wave antennas are easily as good as the commercial ones...
    Where I put the antenna is in a difficult spot to take back down, so most likely I won't be able to bring it to a meeting. It would make for a great demo however.

    Yes I'm sure it would work better with the wires as straight as possible, but it seems to work just fine as is. I have the ground lines spaced fairly evenly from each other.
    Joel


  4. #49
    Registered User Tripplett's Avatar
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    Default Re: FM transmitter antenna

    I could bring mine. In the off season I just straighten the downward radials against each other (so the whole thing is straight) and lay it in the attic.
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  5. #50
    Official Lurker EricR's Avatar
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    Default Re: FM transmitter antenna

    Quote Originally Posted by Tripplett View Post
    I could bring mine. In the off season I just straighten the downward radials against each other (so the whole thing is straight) and lay it in the attic.
    Are your radials stiff enough to not bend easily? Mine are 14 awg solid THHN and tend to bend from their own weight when suspended above the ground.


    Sent from my iPhone using Tapatalk

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    Registered User Tripplett's Avatar
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    Default Re: FM transmitter antenna

    I think mine are 12 awg solid wire. They bow a little but I don't mind a little loss. I still get 3/4 mile range and that's enough for me. As long as I don't have high SWR I'm fine.

  7. #52
    Senior Member mpurser's Avatar
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    Default Re: FM transmitter antenna

    you guys know i still have the swr meter if yall need it
    are you sure we checked every pixel?The Home of North Carolina's Largest tomato cage pixel tree.http://www.thelightsonpurserroad.com

  8. #53
    Stay-Puft! rcktpwrd's Avatar
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    Default Re: FM transmitter antenna

    @EricR like @Tripplett I also used 12 awg solid wire and it is stiff enough to hold its shape/position. The radials sag very slightly but you can bend them upwards to compensate for the sag.
    The biggest issue I have is straightening the wire, it likes to hold the coiled shape from being wound on the roll.

    I might try building a dipole antenna as it would fit in my attic space much better and I could get the wires almost perfectly straight. I'm just not sure if mounting it horizontally would be OK or not, most I have seen are mounted vertically.
    Joel


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