Home » Public Forums » GMCnet » Ham Antenna Mounting
| Ham Antenna Mounting [message #79670] |
Thu, 08 April 2010 00:26  |
captjack
Messages: 271
Registered: February 2010
Location: Sebastopol, California
Karma: 1
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I'm wondering what experience Hams have had with mounting VHF/UHF and HF antennas on GMC's and how they've solved them. Since the body is fiberglass, the usual VHF/UHF antenna would need an additional ground plane, and a mag mount won't work either. Also, I'm thinking of mounting a screwdriver antenna for HF. Have folks mounted them on the ladder?
Thanks,
Jack Christensen - K6ROW,
'76 Glenbrook/Clasco - "The Silver Bullet",
Sebastopol, CA
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| Re: Ham Antenna Mounting [message #79676 is a reply to message #79670] |
Thu, 08 April 2010 05:52  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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My 2 meter / 440 antenna is mounted in the center (side to side) of the roof in the aluminum portion just in front of the hole for the exhaust fan or front air conditioner. It is about 2 feet behind the OEM radio antenna. I have a 5/8 wave Antenna Specialist style antenna up there. That location has a good ground plane and is on the highest spot available on the coach. I have never got around to putting my screwdriver and FT-100 in my GMC. I have seen a couple of people put screwdrivers down low on the rear bumper while driving and then move it to a ladder mount up high when parked. You sure do not want it up high when driving in case you hit a tree limb or something. I would hate to loose a several hundred dollar screwdriver to a tree or low bridge.
My choice for the 2 meter antenna location was easy for me because a PO had already installed a chicken band antenna there. I simply unscrewed it and threw it away. Then I reused the mount and coax for 2 meters. 75 to 90 miles on 50 watts to a repeater site in flat land country in not uncommon using that mounting location.
I run mobile HF in my Blazer but I have never got around to doing it in my GMC. John Richardson and Dan Gregg both run screwdrivers in their GMCs.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Ham Antenna Mounting [message #79741 is a reply to message #79670] |
Thu, 08 April 2010 11:15 |
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Jack,
For VHF/UHF I have an MFJ on-glass antenna mounted on the
drivers window. For HF, I have a Yaseu ATAS screwdriver
antenna mounted to the ladder.
On 4/7/2010 10:26 PM, Jack Christensen wrote:
>
> I'm wondering what experience Hams have had with mounting VHF/UHF and HF antennas on GMC's and how they've solved them. Since the body is fiberglass, the usual VHF/UHF antenna would need an additional ground plane, and a mag mount won't work either. Also, I'm thinking of mounting a screwdriver antenna for HF. Have folks mounted them on the ladder?
> Thanks,
>
>
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Terry Taylor
'74 ex-Eleganza SE
San Lorenzo, CA
http://www.n6mon.org
http://dldesignstore.com
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| Re: Ham Antenna Mounting [message #79748 is a reply to message #79670] |
Thu, 08 April 2010 11:47 |
Rick Denney
Messages: 430
Registered: January 2004
Karma: 0
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| captjack wrote on Thu, 08 April 2010 01:26 |
I'm wondering what experience Hams have had with mounting VHF/UHF and HF antennas on GMC's and how they've solved them.
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I mounted a 2-meter antenna on an L-bracket, bolted to the stock mirror mount. The antenna is a 5/8-wave whip, which can work without a ground plane pretty well. It's so hilly around here that I would not want to characterize its performance, but when there is line of sight, I have no trouble, even at low power.
That antenna uses an NMO mount, which came with 10 feet or so of what looks like RG-174--really narrow stuff. I ran it along the groove between the rubber windshield gasket and the body, and then hang it over the wiper shaft and run it into the hatch. I used a couple of wads of black butyle rubber to hold it in place, and it is surprisingly unobtrusive there.
I've never attempted a mobile HF application.
Rick "KR9D" Denney
'73 Glacier 230 "Jaws"
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| Re: [GMCnet] Ham Antenna Mounting [message #79764 is a reply to message #79761] |
Thu, 08 April 2010 12:56 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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I originally used some mounts I bought at hamfest that used "U-Bolts" to wrap around the uprights to the original tubular mirror mounts for VHF/UHF antennas. One on driver side for normal operations and the passenger side for the APRS system. This worked extremely well.
I have seen a screwdriver HF antenna mounted in the same place, using the same mount.
Since I have replaced the original mirors with RAMCOs (thanks for the mount help to jmk),I have used thru-the-glass mounts, again on both of the upper front side windows, driver's side normal ops and passenger side APRS. However, over this last winter both of these antennas have lost their grip on the glass. I need to re-glue them in place.
I do not have an HF in the GMC, but have a 857D to put somewhere. No real idea on the antenna for HF.
Tom Phipps,
KA4CSG & Marilyn KA4JKW
75 GMC Ex-Avion
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: [GMCnet] Ham Antenna Mounting [message #79767 is a reply to message #79752] |
Thu, 08 April 2010 13:07 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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On Apr 8, 2010, at 11:08 AM, D C *Mac* Macdonald wrote:
>
> As a recent purchaser of a GMC M/H, I'm wondering what
> is the roof made of. I had always "assumed" that the
> shell (top and sides) were sheet aluminum with cast
> fiberglass end caps. Am I wrong here?
>
>
> * D C "Mac" Macdonald *
> ** Oklahoma City, OK **
> * "Money Pit" 76 x-PB *
> _______________________________________________
You are pretty close. The center section of the roof is aluminum as
are the upper sides above the beltline.
The rest is a form of fiberglas that is called SMC.
Here is an article that I wrote for the GMCMI newsletter issue 96,
Summer 2006, that might be of some interest to you.
GMC FIBERGLASS REPAIR
The earliest 1973 vehicles have “hand laid”fiberglass, at least
for the front body assembly. Somewhere between serial number 24 and
50 this process became SMC (sheet molded compound). This was a new
composite material for use in the automotive, industrial, and personal
watercraft markets that presents unique repair problems. Parts made
with SMC are produced in compression molds, so they are smooth on both
the inside and outside. SMC parts do not have an outer gel coat, but
they are usually painted or color molded. When the paint is sanded
off, the underlying surface has a marble appearance. When damaged SMC
is sanded, short coarse fibers are exposed and a dryer powdery dust is
produced compared to conventional materials.SMC is a polyester-based
material, but it cannot be repaired with polyester resin. This is due
to the mold release agent that is present throughout the entire SMC
part. Unlike conventionally molded parts where release agents are
applied to the mold surface, SMC is compounded with them in the resin
mix for quicker processing. This means that as the damage is sanded to
prepare a good bonding surface, fresh mold release agent is exposed.
Polyester resin products are not strong enough to adhere to this
surface. SMC SHOULD ONLY BE REPAIRED USING EPOXY-BASED RESINS, FILLERS
AND ADHESIVES. For good adhesion, when painting, use only catalyzed
type paint systems -- at least for the primer.When a part is broken or
crushed, it is difficult to realign the pieces with each other because
the frayed fibers tend to “hang up” on one another. Use a saw
blade to cut the length of cracks or tears. This relieves the stress
on solid laminates which often return to their original shape with
little force. A router is excellent for removing damaged core
material without disturbing intact face skins. Try to remove as little
material as possible so the repair does not grow too large. However,
solid laminate must be exposed for a good repair.Next, support the
part so nothing gets distorted during the repair process. This can be
as simple as strips of 2 inch wide masking tape or as elaborate as a
custom-made clamping fixture. With the part supported, proceed to
preparing the bonding surface by grinding a taper or steps around the
damage. This is the critical step for functional repairs but it is
also the most overlooked and abused. If a taper is to be used,
measure the depth of the valley and calculate how far the sanding must
extend to achieve the desired ratio. Mark the outer edge of the taper
using a marker and begin sanding inward toward the valley. Be sure to
remove material slowly so the taper progresses evenly. Wet the entire
bonding area with resin, then begin saturating each ply of
reinforcement before it is placed. Work on a sheet of plastic so the
fabric can be easily lifted from the table once it is ready. A
flexible rubber squeegee is the best tool for spreading the resin
evenly through the fabric and removing excess which may be present.
Place the reinforcement into its spot on the repair, ensuring the
proper orientation. Stop every few layers to compact the patch as much
as possible. A squeegee or grooved roller works well for this.
Continue stacking the repair plies at right angles until all the
material that was removed has been replaced. A final cover layer is
then added over the entire area. Sand before painting.
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] Ham Antenna Mounting [message #79768 is a reply to message #79764] |
Thu, 08 April 2010 13:12 |
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My APRS antenne (and it's GPS antenna) are mounted on the fridge vent
cover and the radio package for that is
in a plastic bin that I put in there when we take the coach out.
To remount your on glass antennas, go to your local automotive paint
store and get the BLACK 3M trim adhesive tape.
It is thinner and stronger than the gray stuff. Comes in a 1" wide
roll. You can also use the Larsen/Radiall re-install kits and
just cut the tape to size.
On 4/8/2010 10:56 AM, Thomas Phipps wrote:
>
> I originally used some mounts I bought at hamfest that used "U-Bolts" to wrap around the uprights to the original tubular mirror mounts for VHF/UHF antennas. One on driver side for normal operations and the passenger side for the APRS system. This worked extremely well.
>
>
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Terry Taylor
'74 ex-Eleganza SE
San Lorenzo, CA
http://www.n6mon.org
http://dldesignstore.com
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