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Thread: Antenna wiring

  1. #1
    Senior Member jrevens's Avatar
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    Default Antenna wiring

    I've only found some very general comments on this topic by searching this forum, & I'm hoping to get some additional detailed feedback from builders and perhaps from John McBean (on how they do it on their factory birds). I know that it is generally good practice to separate comm &/or transponder antenna wires as far as possible from the other parallel wiring working it's way forward to the panel. My question is, has it been successful to run those antenna wires together with everything in the same tight bundle or bundles? It seems like it would be nice to run a couple of bundles, from both sides, with everything meeting in the middle, through the center tunnel & up to the instrument panel. Has that worked well for most, or is it a no-no? I'm obviously talking about using good shielding & grounding technique, although the pitch trim actuator wire included in the kit is unshielded (but use of that circuit should be of very short duration & intermittant even if it may be a noise generator). Thanks for any comments.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  2. #2
    Senior Member DanB's Avatar
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    Default Re: Antenna wiring

    John,
    I have pointed a few folks to Bob Nuckolls site where you will find his book on all things electric in airplanes. The name of the book is The Aero Electric Connection and it is well worth the $25 or so bucks he asks for it. It has become a go to resource that many guys here on this list have adopted.
    Take a look at this page http://www.aeroelectric.com/articles.html as it may give you some insight or help. The other thing that helps is to join the Matronics Aero Electric group. When you have an electrical question, it's a great place to go. But Bob's book (in my humble opinion) is the thing to have.
    FWIW,
    Dan
    Dan B
    Mesa, AZ

  3. #3
    Senior Member jrevens's Avatar
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    Default Re: Antenna wiring

    Thank you, Dan. I do have Bob's book, & I agree that it is a great resource. I don't think that the issue/question of running the antenna wires in the same bundle with other wiring is really specifically addressed there though. I'll have to look again. I'd really be interested in any "real-world" experience with the Kitfox specifically in this regard. Do most builders bundle the wires together, or seperate the antenna coax (especially the transponder) from other wires? That's what I'd like to know. I'm running RG-400, & have one transponder & one comm antenna.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  4. #4
    SSFoxBuilder's Avatar
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    Default Re: Antenna wiring

    This is a great question. We are in the planning phases of everything electric for our SS and would greatly appreciate further insight on this topic! Thanks to everyone in advance!

  5. #5
    Senior Member jiott's Avatar
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    Default Re: Antenna wiring

    I am also getting to that point and am very interested in answers.

    Jim

  6. #6
    Senior Member War Eagle's Avatar
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    Default Re: Antenna wiring

    I have run both my comm and transponder cables down through the center console. The transponder antenna cable breaks off and goes to the antenna which is under the passenger seat area. The comm antenna cable exits behind the seat and goes up the fuselage tubing to the antenna just behind the turtle deck.

    I also run a TCAS and the antenna is on the underside of the fuselage about 6 feet back from the transponder antenna location. The antenna cable for that also runs down through the center console.

    All shielded cables and I haven't had any problems that I noticed at all. No one has ever said anything about my transponder or comm transmissions being bad.

    All have passed the regular certification tests.

  7. #7

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    Default Re: Antenna wiring

    Most important think is to use shielded wire for power supply the radio and transponder and to use a specific ground connection different from the rest of the equipments power supplied.
    Good MIL standard wire for coaxial and others.
    The antenna must be at least 6 ft far together.

  8. #8
    Senior Member HighWing's Avatar
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    Default Re: Antenna wiring

    I have always taken the advice to separate antenna cable and power runs. Since the Model IV doesn't have a console, The power bundles run down the door post and aft under the door. The antennas run forward of the door post. The power bundles are near the top under the door and the antenna wires are as far below that as practical. In the parallel runs under the door, they are separated by about four inches. Those runs, I guess, would pretty much duplicate what you would find under the console in spacing and length. This was exactly how I did it on my first Model IV with no wiring issues over almost ten years and 900 hours. When helping a friend with his Series V, we did find that with fuel, control cables and push tubes, it can get pretty tight in the console especially through the bulkhead so in that area compromises might be necessary. On that project we decided to run the antenna wires down the door post and under the seat at the side.
    Lowell

  9. #9
    Senior Member jrevens's Avatar
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    Default Re: Antenna wiring

    I'd like to revisit this subject based on a recent post by Bob Nuckolls on the Matronics AeroElectric List. This was Bob's reply, on 10/18/13, to a question about separating antenna wiring from power wiring:

    "There is no demonstrable value in separating antenna coax wires and other ship's wiring. The idea that 'noise' escapes ships wiring to invade the inner-sanctum of your coax is a popular myth morphed into sage advice."

    This has been my real-life experience for 23 years with my Thorp T-18, where I ran the antenna wires tightly & parallel with other wiring. I have never been aware of any "issues" because of that, & Bob's knowledge & experience gives me a better (warm & fuzzy) feeling about how I've run the wires in my Kitfox project. I just thought some of you builders might like to know this.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  10. #10
    Jch's Avatar
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    Default Re: Antenna wiring

    Thanks for sharing that John. A very timely subject for me as I am building my panel, installing antennae, and ready to run wires and cables this week. I have a SS7 and haven't seen much about how builders are setting up there ground planes. Thoughts?

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