ground question

Discussion in 'CB Radio Forum' started by mr truckdriver, Dec 10, 2017.

  1. mr truckdriver

    mr truckdriver Light Load Member

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    ft myers fl
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    I put a small piece of soft towel under my Wilson magnet mount so as not to scratch the paint on my pickup's roof. Will this affect the ground any.
     
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  3. Timin770

    Timin770 Road Train Member

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    Stole this from a poster on another site:

    "A word of caution - mag mount antennas do not have a direct ground to the metal surface under them. They use a capacitive "ground" (the distance between the antennas base and the car body ) and the distance between the base magnet and the car metal is fairly critical to mainrtain the capacitive ground. Putting even the thinnest material between the two can change the antenna's performance noticably (especially SWR). If the antenna comes with some protective material on the magnet, fine, but once it comes off with age, replacing it with the same electrical properties will be very hard."

    Consider this advice anecdotal unless one or more of the regular gurus here confirms it
     
  4. kc0iv

    kc0iv Light Load Member

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    Take a look at: Magnetic Mount Antennas Don't Suck

    leon
    kc0iv
     
    rabbiporkchop and Timin770 Thank this.
  5. Timin770

    Timin770 Road Train Member

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    I think that seems to confirm what my anonymous source was saying. Thanks for that. Thats one of those facts I think I learned decades ago and forgot
     
  6. Meteorgray

    Meteorgray Heavy Load Member

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    I use magnet mounts exclusively, and currently have antennas in active use ranging from three to five feet. I've had lots of luck performance-wise with them.

    About the scratch question: I used to use a thin plastic piece from a sandwich bag under the antenna magnets to prevent scratches. I've since stopped doing so and have yet to see any scratches from the magnets. I am careful when placing and removing the magnets, being sure to avoid pulling them across a dirty surface by, instead, "tipping" them off the surface. I do make sure the area has a layer of wax on it, and do regularly remove them, which assures no water remains trapped under the bases which can cause paint damage and possibly even rust spots.

    The biggest threat to magnet mounts for me is the increasing use of aluminum, fiberglass or composite materials for truck bodies. So far I've avoided them, but I don't know how long I'll be able to do so.
     
  7. Ridgeline

    Ridgeline Road Train Member

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    Just want to throw something in to this mix.

    The magnet has nothing to do with the antenna other than to secure it to the vehicle.

    The way they are engineered is to compensate or adjust the circuit for the gap the magnet creates between the antenna and the ground.

    Aluminum will work if there is a way to secure the antenna because it is still metal.
     
  8. mr truckdriver

    mr truckdriver Light Load Member

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    ft myers fl
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    Thanks guys always good info
     
  9. Jasonkip

    Jasonkip Bobtail Member

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    Hello, I am a new member here. I am not too much-experienced guy But My grandpa was in this field. He was a Wilson+Stryker SR-490HPC 10-meter radio FAN. And now RIP my dear grandpa. I am not using the Wilson mag mount that's why I am not sure about Wilson mag mount. Because I have Stryker SR-A10 CB Antenna Magnetic Mount (Trucker version too). And I have 16 months of experience with it and yet not faced any kind of problem with it. But here the main question is Will magnet mount so as not to scratch the paint on my pickup's roof. Will this affect the ground any? So, here I want to mention Sir, @Ridgeline. I agree with his statement.
     
  10. Meteorgray

    Meteorgray Heavy Load Member

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    About scratching the paint: Sure a magnet mount can scratch the paint. Any object such as the magnet mount that is dragged across paint has the potential for scratching it, especially if the object has any sharp edges or the surface of the object or the paint have things on them that can cause scratches, such as sand or other grit. As I noted before, I'm careful not to drag the mount across the surface, but instead "tip" the mount upwards when removing it to avoid scratches or excess wear on the paint.

    About the ground: Anything placed between the magnet mount and the surface it is attached to will increase the space between them and thus reduce the RF ground to some extent. The extent it affects the ground depends on how much the mount and the surface are separated. In my case, I used to use a thin piece of plastic, and I could not tell the performance difference although I wasn't trying to measure it either. I'm sure it was affected some, but at least for me it wasn't enough to worry about. Another problem with putting anything under the magnet mount is the fact that the mount could lose some of its holding-down power, thus making it more susceptible to losing the grip during high winds and speeds.
     
  11. craig_sez

    craig_sez Road Train Member

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    novascotia,Canada
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    My sirio mag came with a thin sock of sorts..Its paper thin that fits over the base of the mag itself to keep it from scratching the surface it attaches to..
    Dummy me though,trying to pull just the mag off and couldnt(no ant attached)i dragged it a cpl inches across the roof scratching it...Some how a tiny tiny pebble got between the mag and its rubber grommet..Boy oh boy did it tick me off scratchin my new truck...
    My set up works great but no one around seems to be able to reach all that far for range testing..Only way i test is turn on my 955 in my big rig and record while i drive my pick up..Prob with that is where my rig is parked by alot of stuff it blocks(homes,power wires ect) alot of my signal..So far in around 8-10 mi..
     

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