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  1. #1

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    radio/antenna installation

    Hey everybody
    I'm building a Hatz biplane and am wondering about the radio. Got any suggestions to someone with no clue as to what would be the best way to go? Need to keep the radio as small as possible and need to know what/how to install an antenna to do the job before covering the fuselage. Thanks for thinking about it.

  2. #2
    rwanttaja's Avatar
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    http://www.bowersflybaby.com/tech/velcro.html

    http://www.bowersflybaby.com/stories/antenna.htm

    ...but with your steel tube fuselage, you'll want an external antenna.

    Ron Wanttaja

  3. #3
    DanChief's Avatar
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    I installed a whip antenna in my Chief. Works great with an old Sporty's SP-200 handheld radio!

    http://flightmusings.blogspot.com/20...nna-mount.html
    ---------------------------------------------------
    Dan McCormack
    Smoketown, PA (S37)
    N24286, 1940 Aeronca Chief 65-LA (Lycoming O-145-B2)
    CFI
    http://flightmusings.blogspot.com/

  4. #4

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    Dan is right, a handheld works fine, I use a Terra, a little bulky but stronger output than Sporty's.
    The vital part is a simple external antenna, for the radio to plug into, otherwise it will not transmit with any real strenght.

  5. #5

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    Thanks guys
    I have a Sportys handheld but hadn't considered mounting it. I will now. The external antenna installation looks simple enough. The articles were great. Food for thought...thanks again.
    gpugh

  6. #6
    DanChief's Avatar
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    My "mount" for the SP-200 consists of Velcro on the back and on the panel, with Zip Ties helping to keep it in place.
    ---------------------------------------------------
    Dan McCormack
    Smoketown, PA (S37)
    N24286, 1940 Aeronca Chief 65-LA (Lycoming O-145-B2)
    CFI
    http://flightmusings.blogspot.com/

  7. #7
    Neil's Avatar
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    It is surprising how well a cheap radio will work if it is connected to a good antenna that is properly installed. The simple rod type whip antennas will work as good as any for about the first 100 channels, then it starts loosing ground. That's why they are under 20 bucks. For a belly mount the AV-17 from R. A. Miller and the Comant Ci 122 work pretty good for the money. These antennas are wound which I'm told broadens the channel range significantly. The antenna must be mounted to a satisfactory ground plain. Most Biplanes have a large enough alluminum belly panel to create a good ground plain. A minimum ground plain would be about 18" in diameter. Try to keep the antenna far enough back so it isn't blanked out by the landing gear. Don't scrip on the antenna coax. The RG-58U has been used for years and works pretty good but the RG-400U is the new kid on the block and is a better cable, particularly for transponders. Have someone that has the proper tools make up the coax. Many transmit/receive problems come from improper connections.

    I have a King KY 97A connected to the AV-17 on the bottom of my Acro Sport and it works well. Even sitting inside a metal hangar with the door down I can talk and receive with airplanes flying overhead

  8. #8

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    Quote Originally Posted by Neil View Post
    It is surprising how well a cheap radio will work if it is connected to a good antenna that is properly installed. The simple rod type whip antennas will work as good as any for about the first 100 channels, then it starts loosing ground. That's why they are under 20 bucks. For a belly mount the AV-17 from R. A. Miller and the Comant Ci 122 work pretty good for the money. These antennas are wound which I'm told broadens the channel range significantly. The antenna must be mounted to a satisfactory ground plain. Most Biplanes have a large enough alluminum belly panel to create a good ground plain. A minimum ground plain would be about 18" in diameter. Try to keep the antenna far enough back so it isn't blanked out by the landing gear. Don't scrip on the antenna coax. The RG-58U has been used for years and works pretty good but the RG-400U is the new kid on the block and is a better cable, particularly for transponders. Have someone that has the proper tools make up the coax. Many transmit/receive problems come from improper connections.

    I have a King KY 97A connected to the AV-17 on the bottom of my Acro Sport and it works well. Even sitting inside a metal hangar with the door down I can talk and receive with airplanes flying overhead
    Your off just a bit in your idea of a good ground plane.

    First let's find the middle of the com band.

    137 - 118 = 19 The comm band is 19 Mhz wide

    So the middle of the comm band is 118 + 9.5 = 127.5 Mhz

    The formula for a quater wave is 234 / Frequency-in-Mhz, so we have 1.8352941 Feet or 22.0235 inches.
    In radio a ground plane is normally 5% larger than a quarter wave, so that means 1.1 inch more for a RADIAL length of 23.1235 inches.

    Now since that is the size of one radial it means that a good ground plane would be about 46 inches across. A typical 1/4 wave antenna for
    VHF has 4 radials of 1/4 wave+5% arranged at 90degree intervals.

    In practice if you have a metal ship, or a metal frame, any piece of metal bigger than 46 inches with the antenna at the center of it will yeild good results. If you have a glass or wooden ship you should consider either a dipole antenna or install 4 23 inch radials.


    On the cable front LMR-240 is lower loss than the suggested rg-400u, and will give better results.

    I hope someone finds this useful.

    -Brett

  9. #9
    Neil's Avatar
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    Just said it was a good ground plain, not optimum. A lot of the tube and fabric airplanes sometimes force you to take what you can get.

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