84-96 Corvette antenna mounts

[AB5ON]

We went to the Eureka Springs Corvette Weekend and I saw some really good ideas for antenna mounts, then came back and fabricated some.  They are pretty simple projects.

1. The first is a mag mount plate that attaches to the rear hatch glass.  It is a simple rectangle with 2 5/8ths inch holes drilled 2 and 5/8ths inches apart.  I used 16 ga steel.

2. The second is a 1 and 3/4 inch wide aluminum strap that is 3/16ths thick and about 16 inches long.  I had to bend it in kind of a Z shape so it would drop down under the bumper.  This attaches to a flat spot on the frame under the car with 3 bolts.  It has a 5/8ths inch hole to attach the antenna mount that is a standard insulated 3/8ths inch x 24 stud.  The antenna connection on the bottom takes a standard PL259.  I used a 90 degree adapter so it would not stick down so far.

3. The third one has not been mounted yet.  I used some 22ga steel and folded the edges to make it stiffer.  Then drilled a hole in the end to use an NMO mount.  Since I can't bend this one in a zig zag like #2, I will have to use about 1 1/2 inch spaces to drop it below the bumper.  I think this will look the cleanest since you will not see any coax.  Also my dual band antenna is pretty short so this will be a very low profile set up.

Pictures of these projects are in my Yahoo album here:

http://pg.photos.yahoo.com/ph/black85vette@sbcglobal.net/album?.dir=a301&.src=ph&store=&prodid=&.done=http%3a//pg.photos.yahoo.com/ph/black85vette@sbcglobal.net/my_photos


Let me know what you think.  

73
Rick

[K0BG]

Bases on the photos, it appears the efficiency is rather poor in all cases. While there are VHF/UHF antennas which will operate with minimal groundplanes, this isn't true of mobile HF antennas.

Low mounted antennas are always less efficient than high mounted ones, but when it comes to plastic cars I suspect there isn't much you can do.

Alan, KØBG
www.k0bg.com

[AB5ON]

You are correct.  First, this is a VHF/UHF set up since I don't have a TS-50 or other small HF rig. Secondly, I can't mount a rig where I can easily get to the controls so I am limited to channel up/down on the microphone.

This is very much a compromise since a Corvette does not have a good ground plane. Maybe the gas tank in the rear would make a good reflector?? :-)   I agree that a high mount is superior to a lower mount, but at least on the below bumper mount I am connected to the metal frame instead of plastic or glass.

SWR is not great.  Tends to run about 3:1, but that is much better than a 1:1 with a glass mount.  The bumper mount is actually working out pretty good since I can get a longer antenna mounted there and it does not drag the ceiling in the parking garage at work.

BTW I added a photo in my album of a ZR-1 with the slickest mount I have seen.  It is a below bumper type made of tubing with the bottom cut out to access the coax connector.  You do not see any cable or connector at all.  The cool part is that the owner painted the mount and the antenna the same color as the car.  Very clean intstallation.  I went back three times, but the owner was never with the car so I don't know if he bought it or had it made.

I used to run HF/VHF/UHF mobile with a station wagon which has a great ground plane and I didn't mind drilling holes in the roof.  But the Corvette is MUCH more fun to drive so I am willing to make compromises in the radio performace.

73
Rick

[K0BG]

You might try Lakewood Engineering as they make a license plate mount that just might work.

Alan, KØBG
www.k0bg.com

[AB5ON]

Got a URL?  Did a search on Google for Lakewood and got a company that makes box fans for Walmart.

I saw some mounts like that on 97-04 Vettes and there are some of those in the catalogs.  I think the problem would be that the 84-96 license frame mounts to the flexible rear bumper and not to the frame of the car.  I am a little concerned that the extra stress could damage it.  Also, the light for the plate is above it.  On the antenna mounts I saw, they would block the light.

I think as far as looks go, the license plate mount looks good and the higher mounting position would be better for some antennas.  I did see one that a guy fabricated out of plexiglass.  That has to be about a zero ground plane.

I'll keep searching for Lakewood.  Thanks for the tip.

[AB5ON]

Alan;

Might this be Lakeview?  I did find the two following products and some reviews/discussions about them.  Pretty much the same concerns I had about mounting to the plastic bumper.

Anyway for those interested here are two products that were interesting.

http://www.hamstick.com/Tm-1.html

http://users.allegan.net/prosoft/mount.htm

Rick

[AB5ON]

Had a user on Corvette Forum send me this link to a picture of a bracket he made that mounted to the spare tire carrier using the bolt that holds the carrier in place and a metal bracket on the carrier for the end of the mount.  Very innovative!


http://www.photohost.org/gallery/data/592/5461MVC-013S-med.JPG