External antenna mount for HAM radio

[BoDuke]

I recently attained my amateur radio license, so I'm looking at different ways to mount an antenna on the C5. Obviously with the car being fiberglass, a magnetic mount isn't going to be an option.

I've seen the CB antenna mounts that attach on the top side of the rear license license plate, but I am NOT spending $150 for an 'L' bracket. Granted, I can make my own, I may venture in to that.

I thought I ran across an antenna mount that mounted underneath the rear of the car, by the rear passenger side. Anyone else see this set up?


I will prolly end up fabricating my own mount set-up, I just thought I'd check with everyone else first. Thanks in advance for the perspectives!

 

[Hib Halverson]

I don't have any answers for you, but I am interested in the progress you make on developing an antenna.

What amateur radio frequencies are you building the antenna for?

I want to install a 50W GMRS mobile in my C6 for use during the National Caravan. It's a UHF transceiver and I, also, am looking for good ideas for an antenna.

 

[kpic]

BoDuke
For which band, HF, VHF or UHF? The only mounts I have seen for a Corvette are the trailer hitch mounts. :ugh For VHF or UHF, you can get a glass mount which work by capacitive

If I was going to add an antenna, I'd probably mount it at the rear, between the exhausts.

RFI (radio frequency interference) would be a consideration. I know GM and Ford offer RFI filters and my guess is so do other OEMs. However, sometimes what they offer doesn't do the job.
RFI issues in the Ford Explorer Although the URL is 97vette.com, his problem was a Ford Explorer.

Some of the issues are interesting: Radio Expert Unlocks Malfunctioning Key-Fob Mystery | Vehicles & Technology content from WardsAuto

I've held an Extra Class ticket since the early 1980s, my interests are DX and CW. If you are involved with a Ham Club, 2 meters is essential.

Hib,
GMRS is 462 - 467 MHz. If you haven't bought one yet, eHam.net Reviews and search for GMRS. There are HT and antenna reviews. HT is what hams call a walkie talkie. As they are cheap, I'd also buy a HT for when you are out of the car.

A 50w RF field might cause some interesting interactions? I would test it for RFI (radio frequency interference) before your trip. A dealer will be quite useless if you have a problem.
What would be nice would be a glass mount antenna.
http://www.theantennafarm.com/catalog/antenna-specialists-ap454-3-854.html It's bandwidth is 410-512 MHz and it handles 100w. It is unity gain so your power output is not multiplied. Be sure the connector you choose matches the one on the radio. ]If you post the brand name of the radio, I'll tell you which connector you want to get on the antenna. I am not recommending that antenna, just trying to help.

Please read this before mounting a glass mount antenna: http://www.antenna.com/artifacts/20101018MIS-ONGLASS-RevisionC-090910-2.pdf

My C5 has a diversity antenna, FM on the front windshield and AM/FM on the rear. On FM, depending on signal strength a module switches between them. I do not know how a C6's system operates.

When it comes to drilling holes or hitch mounts, I have a 4WD truck or her Edge.

As my profession is mechanical engineering, I'm not an eight hour a day double E or technician, but same as most Hams, I get by with electronics. If I can be of any further help to either of you, let me know.

 

[BoDuke]

Hey there Hib! I'm planning on having a basic antenna for 2m/440. It'll prolly be a Diamind Antenna, 17" +/-. I'm not gonna be DXing while in the C5, so I'm needing something just to get me out from the cabin of the car.

I just got the Yaesu FT-60R hand held from Ham Radio Outlet, along with the current repeater guide. For a hand held, its doing good job. When in the car though, it could really use an external antenna and headset with PTT. However, I got the FT-60 for secondary and emergency com's, and not primarily for vehicle use. It's definitely a nice rig and enjoyable here on the local repeaters.

For mobile, I'm going with the Yaesu 8800R. Since I drive truck here in the midwest, I'm going to mount it in my truck. However, I will get 2 additional separation kits, one for the Suburban, and one for the C5. My plan is to have all the mounts, wires, and coax permanent in all 3 vehicles, then I'll just need to pull the head and main box out, put it in whichever vehicle I'm using, and voila, 2m/440 wherever I'm at.

I take the C5 out of state on Corvette runs, but I take the Suburban to Omaha for the weekend, and will also be taking it to Idaho this fall hunting. Instead of having a $400 rig in each vehicle, 2 $50 separation kits and antenna's seem like the viable solution.

I'll mainly be using 2m/440. I'm not going to go all crazy with frequencies while mobile. Using the 8800R here at the house as a base station, that's another story.

Antenna's, I'm looking at the Diamond brand. I was thinking something along the lines of the SG-7500A and SG-7900A. I don't really need anything fancy. But I do NOT want a trunk lid/hood mount type system. I have no problem putting a hole in the top center of the Suburban for a good antenna.

As my C5 is a vert, I'm not sure the glass mount is the best option for me. It appears that once the coax is connected, the line would come down the outside of the rear window, across the deck lid, and under the front side of the trunk lid. I'm not sure I'm comfortable with the coax being on the rear deck, might scratch the surface. I am going to consider that for the Suburban though...it'd save a hole in the roof!

I appreciate the links and the good ideas, extremely helpful!

Now that my devious plan is out, if there's any specific ideas available, feel free to share! Thanks again!

73's
Aaron
KE0ASW

 

[kpic]

Aaron
Just use a dual band (2 meter/70 cm) glass mount on the Corvette, no holes and you can remove it. Just follow the instructions in the link to a pdf I posted.
I would be neat to use the defroster grid as the ground plane, but that would be home brew. Although I've been a hired gun for contests , I'm not into VHF or UHF. Pretty much pure HF, DX and CW.

As far as the Suburban you can use magnetic mount (no matter what they say it will scratch the roof) or a one of those mounts which attaches to the roof rack. Sort of a piece of strap which attaches to both sides of the roof rack. As they are mounted in the center, they get a reasonable ground plane underneath them.

The Diamond 7900 wants a hole and it sounds as if the 7500A can use a mag type mount. It sounds as if the 7500 is a half wave on 2 meters and two 5/8 waves on 440. The 7900 is 2 1/4 wave + a 3/8 wave on [SIZE=-2][SIZE=-2] [/SIZE][/SIZE]2 meters and 3 5/8 wave on 440. They do not mention phasing so they are omnidirectional.

Enjoy

 

[BoDuke]

Hey there KPIC,

I looked at the C5 this evening and antenna bracket mounting scenarios. Mounting to directly above the license plate doesn't seem like that good of an idea. I didn't realize it's just that thin piece of rear facia, and that it was all hollow behind there!

So, looking at your suggestion of mounting between the exhaust... I think I can make a bracket out of aluminum, and plasti-dip it black.

Here's the initial idea...In that metal piece that runs left to right by the mufflers, I'm going to bolt on a home brew T. The top of the T will be secured to the car, and the bottom of the T will protrude out from under the car, clearing the rear fascia. I will make a similar T to mount to the area above the license plate. So, now we have 2 horizontal planes. I will weld the hollow bar between these 2, making the 3 in to 1 solid bracket. The top piece will over hang the vertical bar by a bit, 2 inches maybe, as this is where the mast will mount. I'd like to mount something on the lines of a 'Buddi-stick' to that, then the antenna on top of that. I'd like the base of the antenna to be about trunk lid height. I'll zip tie the coax the the mast down to the top brace, then under and behind the fascia in the space by the license plate lights.

With this set up, the brace will be solid to the car, the antenna above the car, and wind shouldn't sway anything. I could mount the antenna on the top brace, but I'm afraid wind will whip the antenna in to the fascia and scratch.

If it works, I'm gonna have to call that patent number I keep seeing in my spam folder otfl

Also, this would be a nice, solid set up that will allow the mounting of bigger antennas. Maybe someday the C5 will be outfitted with a Scorpion :ugh

Let me know what ya think!

 

[kpic]

Sounds good. If you make the T under the car heavy enough, it should hold the antenna unassisted. A tennis ball with a hole pushed onto the antenna will keep it from touching the car.
As the frame will be your ground you may have a cartoidial pattern or lobe to the front.
GM used to offer an RFI kit, not sure if they still do or not, if not welcome to toroid cores. Usually in every Ham club there is someone who is good with RFI. I'm a climber or tower monkey.

I used to take a F9 Tonna beam and park up on a mountain and clown around on 2 Meter CW or SSB with 100 watts.

73's
-Ken