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Author Topic: Antenna Mount on Fiberglass Campertop  (Read 2235 times)
AF4YA
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« on: February 22, 2001, 10:36:39 PM »

Would it work if I lined the entire inside top of the camper shell with a piece of sheet metal, ground it to the frame of the truck and drill through the fiberglass and metal to place a permanent mount for a 2m/440 antenna?  Has this been tried before? Just from speculation it would seem to have a better ground plane than the same mount drilled through the top of the cab due to larger surface area.

Thanks,
Nick
AF4YA
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WB2WIK
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« Reply #1 on: February 23, 2001, 05:34:19 PM »

Of course this works.  You really don't have to ground it to the frame, it shouldn't matter.  When I had a Corvette (fibreglas) I did this inside the trunk, to make a ground plane for the VHF whip, and it worked splendidly.  And if what you describe works "better" than installing a whip in the center of a car roof, it's probably because the whip on the camper is up higher above ground!  I rented a huge motor home once, years ago, and used duct tape to tape a sheet of galvanized steel about two feet square to the roof of the RV, snapped a 5/8-wave mag mount on that, and had a very BIG signal due to the antenna height -- my antenna was several feet higher than the average car.  It does make a difference!  Good luck & happy RVing.
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AF4YA
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« Reply #2 on: February 23, 2001, 11:46:55 PM »

Sounds good. Only problem is I just found out today that the campertops I'm looking at have a 1" think honeycomb fiberglass roof. Unfortunately no one makes a roof mount that is tall enough to go through 1" of fiberglass and then have enough thread left for the antenna to screw down on. I have seen a few possibilities but all of them take alot of jerry rigging which I'd really like to avoid. Seems like anyway I look at it, I'm going to have to drill through the cab. I just hope that it doesn't decrease the value of the truck when I sell it.

I appreciate the reply very much though, take care and 73s.

Nick
AF4YA
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WB2WIK
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« Reply #3 on: February 26, 2001, 01:50:43 PM »

Hey Nick, if you haven't drilled the hole through the cab roof yet...

...Both Larsen and Diamond make mobile antennas that use the SO-239 mount.  That is, the antenna base is a heavy-duty PL-259 connector, and the mount that it is intended to screw on to is a conventional SO-239 "UHF" receptacle.

Those receptacles come in many forms, including a very, v-e-r-y long and deep double female adapter that is threaded all the way from one end to the other, and mounts with a pair of hex nuts.  The overall length of this bulkhead adapter is about 2-1/2", will easily pass through a 1" panel and leave space for connectors to be screwed into both ends.

You might want to consider it...

73 & happy mobiling!

Steve WB2WIK/6
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AF4YA
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« Reply #4 on: February 28, 2001, 11:48:52 PM »

I haven't gotten to it yet. I had heard of using a bulkhead adapter, but wasn't sure about it. I wonder about the problems of sealing it correctly and if the connector could stand up to the harsh conditions. I try to avoid rigging things up as much as possible;)

Thanks for the info though,
Nick
AF4YA
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N9TJX
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« Reply #5 on: March 01, 2001, 02:31:29 PM »

Nick,
Another idea for you to be able to use NMO mounts is to make a metal channel that you can mount to the roof.  We use one in our ESDA's Incident Command Center.  We have 2 channels one on each side of the vehicle, and have 14 NMO mounts. I am not sure how the channels attach to the fiberglass, but I can check, and give you more details if interested.

Jonathan (N9TJX)
n9tjx@arrl.net
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G8OSN
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« Reply #6 on: March 12, 2001, 07:51:32 AM »

Hi,

I had a similair problem with my people carrier (or MPV as it is known in the former colonies ;-) ).

I used dual band antenna from Maldol which is a 2m 1/2Wave an 70cm 5/8 over 5/8, neither of which need a ground plane. I made a small aluminium bracket which screwed to the roof bar. SWR is 1:1 with a needle width across UK 2m and 70 cm bands and it on air peformance good.

73
Brian
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