New install on Aluminum top Willys jeep

[Guest Mark Wahlster]

Looking for some best advise. I'm very knowledgeable when it comes to CB radios and their antenna quirks. First radio I was on as a kid was a Heathkit HW-30 Twoer "Benton Harbor Lunchbox" 2 channel 6V Tube set Dad built on the kitchen table in 63-64. It was installed in the same Willys Jeep I am working on now. Then on to Johnson Messengers like the III I still have, I drive dump truck and use a Cobra 29 CB all day long.

 

BUT GMRS is a new critter to me.

 

Here's what I want to do.I want to mount a Midland MXT-400 to the ceiling in my Aluminum hard top then mount the antenna (most likely a Midland Ghost 3db) in the center of the 5'x6' aluminum roof. This will "require" only about 3-3.5ft of coax. Or should I wad up the extra cable and stuff it in one of the insulation compartments in the ceiling of the top (it will have 1" of Blue foam insulation in the ceiling)  Whats the best way to do this.?.

 

Next question If I set this up using the Ghost antenna about 3" tall can I just swap on the 32" 6db antenna when I am out in the boonies?

[Lscott]

I would be VERY careful mounting a tall antenna on an aluminum roof top. Torque from highway speeds hittong the antenna on tree limbs etc. can damage the roof. Even people with a steel roof had sheet metal damage at times.

 

The sheet metal used on many vehicles now days is rather thin. You should consider using some extra bracing under the area where the antenna mount is installed.

 

A few antennas have an optional spring at the base that does a good job of saving your roof top in case of an accidental contact between the antenna and the obstruction.

 

The major advantage to the “ghost” antenna is the very low profile. You can almost forget it’s there as far as pulling in to a garage, parking deck, drive throughs etc. However they are not the best antenna for long range communications.

 

If you have just a few feet of extra coax I would just neatly coil it up and stuff it out of the way. A lot of extra coax you might want to consider cutting it shorter and installing a new connector on the end. Most mounts use RG58 coax which is rather lossy at UHF frequencies.

[BoxCar]

Either antenna will work on your top. The addition of an extra thickness of metal as a brace may be difficult because of the NMO mount the antennas use. Often there just isn't enough length on the mount to go through two thicknesses of material. I would shorten the coax just for a neater installation but that's your call.

[SteveC7010]

If you use a 3/8” NMO mount instead of a 3/4” one, you will have less issues (if any) with deformity of the roof. It’s easier to drill, too.

 

I wouldn’t bother with the ghost antenna. Instead a standard UHF 1/4 wave whip will do fine and be less visible. They’re usually $10 or so so you can easily afford a spare to keep in the Jeep just in case.

 

If you or some one you know has the skills and tools, by all means shorten the coax, but leave a foot or two extra.

[Extreme]

Lots of different NMO mounts available for various mounting thickness: 

 

https://www.theantennafarm.com/catalog/mobile-antenna-mounts-264/permanent-hole-mounts-266/3-8-nmo-hole-mounts-1291/

 

I'll be installing a 1/4 wave on my Cherokee XJ that has a super thin roof so will probably back it up with something.

 

Here's the antenna I use (and I carry and have used spares on my SxS).  It has worked A1 for me and is only 6" long.  If you look you'll find experts here saying 1/4 is still best bang for buck for ground comms unless you're trying to hammer elevated repeaters.

 

https://www.theantennafarm.com/catalog/laird-technologies-ab450-4476

 

ADD:  I think Antenna Farm will build custom length coax.