*3/8x24 Antenna Stud Substitute*
Recently Iíve had bad luck with the common mounting studs for mobile antennas. The center easily pulls out of them when I started to tighten the antennaís nut. The one pictured below tightened up, but when I shook the antenna it then loosened and fell apart. That is unsatisfactory especially on a vehicle. Iíd feel comfortable using them at a base station, but driving down the interstate and having antennas fall off would not be a good thing.
To resolve the problem, I used a 3/8x24 bolt, 2 lock washers, 2 Teflon insulators and a fender washer. The feed point is coax terminated to soldered-on connectors. I used rubber splicing tape and then vinyl electrical tape to seal the end.
In order of assembly. Bolt, lock washer, Teflon insulator, fender washer. That goes up through the bumper and through another Teflon washer and then lock washer. Then the 3/8x24 nut screws on.
Before installing anything I used a wire wheel and cleaned the bottom of the bumper to create a good ground contact.
To load the antenna the ground connector compresses between the fender washer and bumper.
The center conductor compresses between the bolt and Teflon insulator.
The purpose of two Teflon insulators, one on top of the bumper and the other on the bottom is to isolate the bolt from the bumper.
This assembly is tight and the SWR is minimal.
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