Mobile Questions

Discussion in 'Mobile Radio Systems' started by KG4HNY, Dec 10, 2012.

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  1. AD5MB

    AD5MB Ham Member QRZ Page

    tailgates and tire carriers grounding problems are made worse by rust, grease, dust, oxidation...
  2. M0GVZ

    M0GVZ Ham Member QRZ Page

    A good DC path doesn't make a good path for RF. RF flows on the surface of a conductor, not through it. So whilst a certain diameter of cable may be good at shifting 20A of DC, it has very little surface area in comparison to say flattened braid from RG213.
  3. M0GVZ

    M0GVZ Ham Member QRZ Page

    Look at this picture


    Measuring the resistance between the tailgate and body of my two year old Ford Mondeo it was 72 Ohms. Remember that this is across an all metal hinge with bolts that go directly to the tailgate and the body of the car on a car that is only a couple of years old with rustproofing and no corrosion. After I added some grounding straps it was zero ohms.
  4. KG4HNY

    KG4HNY Ham Member QRZ Page

    It's all coming together now....

    I plan on mounting my radio under the passenger's seat with the faceplate up above the rear view mirror. How important is strapping the seat frame to the tub? Or even the radio to the tub or seat frame somehow?
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I wouldn't mount the panel above the rear view mirror.

    In some states, that's not even legal (like here in CA, where the laws are very specific about where you can mount things around the windshield -- even a small GPS cannot be mounted there; you must mount one in the lower right or lower left corner of the windshield and nothing near the center if it's above the dashboard) but even where it would be permitted, I don't like the idea of mounting anything around "head height" that could become a flying object in a collision.

    Another issue is the LCD displays, when they get "hot" from the sun, can go "all black" and you can't read them. That doesn't really damage them, as they work okay again when they cool off. But on a sunny summer day, mounting anything where the sun can shine on it can cause the "no display" problem.

    I'd mount it down lower.
  6. KA9MOT

    KA9MOT Ham Member QRZ Page

    And mount securely. Even the parts that are under the seat. Again missiles in a wreck. Don't mount anything under the dash on the drivers or passengers sides. In a wreck you'll slide forward and down before the belts catch you. I have a 4 inch scar on my knee that came from an external speaker that was mounted to the side of my center console. 3,000,000 miles accident free in a big truck, but I tore the hell out of a hot rodded 1979 Olds Cutlass once. Something I'll never forget.
  7. KC9UDX

    KC9UDX Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    A Jeep seatbelt should not let you slide forward. This is a serious gripe I have with all the factory seat belts. I don't know what they were thinking. You may have small collision-like forces once every ten years in most vehicles, but if you are putting your Jeep to use, you may have ten a year (or more). Having everything tight and secure is mandatory.
  8. KC9UDX

    KC9UDX Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    The seat is always important because like the above tailgate, it is mounted on a hinge. But, it only matters if there is reason for RF to be flowing through the seat bracket. If you run a strap from the radio to the tub, you are bypassing the entire seat bracket assembly.
  9. KG4HNY

    KG4HNY Ham Member QRZ Page

    Yes, this is the plan. I plan to use the tub as the main component of my bonding with everything else branching from there. As for the sun problem, I have the top and doors off most of the summer. I will look other places, but above rear view mirror may be some of the only shade I can get.
  10. KC9UDX

    KC9UDX Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    What will you do when you put the windshield down? That's always a concern of mine.
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