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eHam Forums => Mobile Ham => Topic started by: KF7ZFC on December 13, 2007, 11:30:23 AM



Title: Ground for 3 mag mount on roof 2002 Ford Explorer
Post by: KF7ZFC on December 13, 2007, 11:30:23 AM
Have checked with ohm meter luggage rack is not grounded to car. Have 3 mag antenna mount that I want to ground can't find any place to do this. has anyone done this to a 2002 Ford Explorer?

Thanks
Steve
KC2ICL


Title: Ground for 3 mag mount on roof 2002 Ford Explorer
Post by: K0BG on December 13, 2007, 12:59:23 PM
I answered this once, but I don't know what happened to the reply.

There is a difference between a DC ground, RF ground, and ground plane. In this case, about all you can do it drill a hole.

If you need more information, visit my web site.

Alan, KØBG
www.k0bg.com


Title: Ground for 3 mag mount on roof 2002 Ford Explorer
Post by: KT4NR on December 17, 2007, 01:18:35 PM
You have to drill a hole in the car and the support for the magmount and run a piece of 1" braid or copper strapping.

Better yet...

Ditch the magmount and bolt the antenna on the car.

Dan S
KO1D


Title: Ground for 3 mag mount on roof 2002 Ford Explorer
Post by: WA7NCL on December 19, 2007, 03:30:33 PM
You could theoretically add some sort of conductive tape or foil to the roof, with the aim of creating enough capacitive coupling to the auto body to act as a ground.  If it was copper tape or foil, there would be the disimilar metal problem and who knows whether the adhesive would eventually pull off the paint.

I'm not sure how much capacitance you could get.  The paint is probably really thin, so the capacitor plate spacing would be small.  An explorer is fairly big so you have a pretty large roof area so a large plate area.

It would be an interesting experiment.  Unfortunately probably as ugly as a hole and big chunks of braid.


Title: Ground for 3 mag mount on roof 2002 Ford Explorer
Post by: K9WI on December 22, 2007, 04:42:43 AM
Loose the mag mount!

I use a home made roof rack platform that works really well for me on my 98 explorer.  It is made of steele and alumnimum.  The steele part are 2 three foot box style stock with holes pre-drilled every 3 inches or so.  The Alluminum are 2 four foot aluminum L s (I think two inches on each side - I bought a 8 foot length and sawed in half).  

The 3 foot box members are bolted to the roof rack rails with carriage bolts, washers for spacers (I used 11 for each bolt, and steele mending strips that matched the hole pattern on the box members and some rubber cussion material to protect the roof rack rails).  I left about 3 inches on each end beyond the roof rack rails to bolt on the aluminum, 90 degrees to the box members. Kind of a giant "H".

All this is positions so the back aluminum is directly over the gap in the rear hatch door.  I then used 2 inch braiding, in three places, from the alluminum to the body of the explorer.  Open the rear hatch and look along the top edge, you will see some flat areas.  That is where I drilled some holes, and attached the braid with sheet metal screws.

I painted the steel and aluminum flat black, except for where the braid was attached, the alumunum and steele overlapped and where the antenna mounts are located flat black after a coat of primer.  I also coated the braid with black liquid electrical tape.

It looks really nice and now you have 4 or more mounting points for antennas.

I can send you pictures if interested.