Antenna mount Question

I have never been able to get a good SWR reading when mounting an antenna to a tool box!
You need a good rf ground, as in the antenna needs to "see" a good portion of your vehicle, the metal parts that is, for it to work properly. I've tried mounting on the tool box on three different trucks and was never satisfied with the results. This last truck, 2000 GMC Sonoma, I couldn't get a good SWR on the bed anywhere. Ended up first using the left front fender, which worked well but i didn't like the look. Then finally just drilled a hole in the roof and mounted a Wilson 1000. The roof is the ideal place, unless you drive a rag top!

 

yes the whole vehicle needs to be your ground plane.if you use an aluminum mount or tool box you must run a ground strap to the FRAME of the vehicle.not the bed,its not grounded.thats why people cant get a good swr.up against the back of the cab is ok as long as your grounded to the frame,and if its loaded/coiled,that needs to be above the roof line.

 

I ran one heavy duty 1" braided ground strap to the frame and it made little improvement. Talked to a guy fighting the same thing and he had to run 4, one on each corner to do any good. That is when I decided to move the antenna to the front fender.

 

Yes you will most likely need to ground the metal tool box to ensure it has a good ground. Although it is also highly likely just the bolts alone are enough to give you a ground.

You could run some star washers too between the bed and the tool box where the bolts go thru to ensure you have a good bite.

What kind of antenna do you have?

As the others said, the roof dead middle is the best spot, as you want the antenna as high as you can get it. Also mounting the antenna on the roof dead center ensures you get out equally all around. Mounting it to the corner of the bumper just makes you very directional in the area where there's the most amount of metal. i.e. if you mounted the antenna on the right rear bumper corner, you will be more directional towards the left front of the vehicle.

FWIW I ran a 102 whip on my S-10 on the rear bulkhead of the bed in the dead center. Only a foot of my antenna was obscured by the cab window. But I could get out 10-14 miles any direction, on a stock 4 watt Cobra radio and no amp.

 

Wilson makes a 1000 roof mount. Good antennas.

 

I used a stake hole mt. with a 102" steel whip. It worked very well and the SWR was around 1.5:1.

I used the hole behind the passenger seat and ran the coax through the right body rear air vent - the 'pressure reliever' one. It was a chore getting it through there but no hole had to be drilled.

The stake hole mount was the type that has two bars underneath that are drawn up by 4 screws to clamp to the underside edge of the stake hole.

No spring should be used because the antenna will fly all over the place.

With no spring, the antenna would sometimes whack the back of the cab. I placed some 1/4" rubber hose over the antenna. This made it heavier and more likely to lean back on the highway but it protected the cab paint. It also looked good.

#1 as has already been said is a good ground between the antenna mount and the steel of the bed. In my case the bed had been electrically strapped to the frame underneath.

The location is close to cab existing wiring in a 2004 silverado. During some experimental tests the RF did not interfere with the vehicle electronics until the power level was about 100W carrier.