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Thread: Vehicle grounding

  1. #1

    Default Vehicle grounding

    Hello all! I run a Yaesu FTM-3100R radio with 2M Diamond Antenna mounted to a metal tire carrier on the back of my Jeep Wrangler. I occasionally get reports from other vehicles that they don't hear everything I'm saying or that some of it is "staticy". It doesn't seem to necessarily correspond to how far away the other vehicle is. I have a small handheld radio as well and never get the same complaints even when using it from the inside of my vehicle. Someone told me it was likely a bad ground so I did some looking into it. What I've done:

    1. Using a multimeter I tested the resistance between the negative terminal on the vehicle's battery and a bolt inside of the front of the vehicle's frame ( frame itself is coated ). it reads about .5 ohm resistance. As far as I can tell by researching this that is well under what is needed for a good ground.
    2. I tested the continuity from the antenna's mount plate on the tire carrier to a bolt inside of the vehicle's frame in the rear ( multimeter's cables won't reach to front ). It reads about .5 ohm.

    Assuming my frame is connected front-to-back the ground should be good all the way through as far as I can tell. Am I missing something in my method? Would an additional grounding cable help from the antenna mounting plate to something on the frame?


    Last edited by owenb_; Thu 3rd Oct 2019 at 00:54.

  2. #2

    Join Date
    Nov 2017
    With my wife


    If the tire carrier is mounted on a hinge or on a hinged door of any kind, don't expect a great continuity of ground at any time there is sufficient vibration to disturb it (i.e. driving). Running a piece of wire as a DC ground sin't going to cut it either, because the antenna is looking for a ground plane in this case.

    Look here and do a bunch of reading, there's stuff there to clear up any misunderstandings concerning mobile operation.

  3. #3
    K7KBN's Avatar
    Join Date
    Jul 2008
    Bremerton WA USA


    Hinges absolutely can't be relied on to provide good electrical contact. Sliding contact basically equates to NO contact.
    Pat K7KBN
    Semper ubi sub ubi.

  4. #4


    More likely overloading their front end on their radio. Try on low power.

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