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Author Topic: vhf mag mount and aluminum roof  (Read 2327 times)
N1RND
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Posts: 69




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« on: October 22, 2012, 09:24:16 AM »

The roof of my semi truck  tractor is aluminum.  I can attach a small piece of steel so it will grab.  Will this piece of metal have to be screwed to the roof for good ground plane action?  I was thinking of usi
ng epoxy.
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K5LXP
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Posts: 4439


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« Reply #1 on: October 22, 2012, 12:07:16 PM »

If you can screw a steel plate to the roof, why not just use a permanent (through-hole) antenna mount?  Usually it's aversion to drilling holes that folks use mag mounts.

The magnetism of the base isn't contributing anything to the antenna other than as a holding force.  However you get it to "stick" will work.

A few dabs of construction adhesive underneath a mag mount would be "permanent".  A bead of silicone seal around the edge would be pretty durable and removable in the future.


Mark K5LXP
Albuquerque, NM
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WX7G
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Posts: 5908




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« Reply #2 on: October 22, 2012, 12:24:04 PM »

A 4" x 4" plate glued with 0.1" thick epoxy has a capacitive reactance of 8 ohms. The coax will be hot with RF.

If you can make the epoxy much thinner it should work.
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N1RND
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Posts: 69




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« Reply #3 on: October 22, 2012, 05:34:32 PM »

I already have the mag mount.  I guess what I am asking is what is the relationship of a mag mount on non ferous metal.  If a mag mount was placed on an aluminum ground plane, even though it won't "stick", would it still couple RF wise?
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WX7G
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« Reply #4 on: October 22, 2012, 06:25:09 PM »

Yes if you can bond the mag mount to the roof with a very thin layer of epoxy it will work just like it's on a steel roof. By thin I mean less than 1/16 of an inch.
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W9MMS
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Posts: 118




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« Reply #5 on: October 24, 2012, 10:16:12 PM »

WHY do you need to mount the Antenna on the Roof of the Truck?
The Mirror bracket will suffice.
If you are dead set on mounting it on the roof, then drill a 3/4" ID hole for the Antenna using a NMO mount. Aluminum works just as good for ground plane.

BTW, I mount my UHF/VHF Antenna ( Kenwood TM-D710A) on the Grad handle on the driver side of my big truck.

(((73))) Milverton
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M6GOM
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Posts: 862




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« Reply #6 on: October 25, 2012, 06:49:38 PM »

WHY do you need to mount the Antenna on the Roof of the Truck?
The Mirror bracket will suffice.


Please don't ever advise anyone how to install a mobile antenna if you truly believe that.
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W9MMS
Member

Posts: 118




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« Reply #7 on: October 26, 2012, 04:02:55 PM »

WHY do you need to mount the Antenna on the Roof of the Truck?
The Mirror bracket will suffice.


Please don't ever advise anyone how to install a mobile antenna if you truly believe that.
The proof is in the pudding!

 http://aprs.fi/#!call=a%2FW9MMS-14&timerange=3600

It is up to you if you want ti believe or not.

(((73))) Milverton.

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