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Discussion Starter #1
I installed my Cobra 75 with a 4' firestik on my Taco this weekend. My idea was to build an antenna mount for the bed rails so I can take it off when not in use. It all looks great. Problem is (I hope) grounding the antenna. Because the bed is plastic I have to jerry-rig something.

First I tried running a wire down to the frame (about 2.5 feet). I was skeptical about this since it's so long. My cheap, crappy Radio Shack SWR meter pegs out when I key the mic.

Next I tried a shorter wire (about 8") to a bolt on the bed. It's the closest thing I could find. It's tough to get to because it's between the bed and cab. SWR still pegs out.

I know I have a true ground on both. I checked it with an ohm meter. There are no kinks or damage to the coax. The "plug box" for the Cobra 75 is mounted and grounded. The power is correctly grounded. I get a strong, loud signal on the weather radio. So it seems to be all hooked up right.

What else could I be missing?

(I have pics, but this is my first post, so no pics allowed. ;) )
 

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The length of the ground wire is not important. The next step is to 'tune' the antenna using the screw in the tip.
 

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Discussion Starter #4
Do you have the nylon bushing in the right place on the antenna mount?
Yes, I had the bushing in the right place, BUT...

I have found the problem. The stud is grounded!



I took it apart and after removing the washer from the ground side (opposite the bushing), it was correctly insulated. The washer I got with the mount was too small and was touching the middle (insulated core) of the adapter stud.

I've got it mounted now and getting an SWR of 2.0 with the shorter (8 inch) ground line. (The frame ground was still over 3.0.) I'm hoping to tune it better when I get home.

Thanks for the help!
 

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NorCal Chapter Pres
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Remember to check the SWR on multiple channels and get it close to the same by changing the length of the antenna.
 
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