Mobile Antenna Mounting

[Mark Jack]

Has anyone had any experience mounting antennas on a Chevy Avalanche? I've recently upgraded to a Yaesu FT8900R with a Diamond CR8900A quad band antenna. Unlike my old SUV I am limited on mounting locations that will produce a sufficient ground plane. I am trying to avoid mounting on the roof so I don't have to worry about height in certain locations as the antenna is 50" tall, but will if it produces the best results. The two main areas I have been looking at, based on what I've seen online, are a hood mount that bolts to the side, or mounting to the grab handle location on the rear of the truck bed (attached are pictures of both). Any and all suggestions would be greatly appreciated.

 

[Jack R. Jester]

Do you got a steel rear bumper on your avalanche? That should act as a good grounding plane, I've seen many people mount them like that.

I almost did that on my '95 Suburban, but I ended up probably doing it completely wrong by screwing it to the quarter panel (I didn't want to spend any money).

 

[Jack R. Jester]

Don't be afraid to drill some holes (Unless your paint is actually nice unlike mine).

 

[Mark Jack]

I'm not too worried about the paint haha. Also, the rear bumper is entirely plastic so that definitely doesn't help.

 

[Jack R. Jester]

I'm not too worried about the paint haha. Also, the rear bumper is entirely plastic so that definitely doesn't help.

What year Avalanche do you have?

 

[Mark Jack]

What year Avalanche do you have?

2003

 

[Jack R. Jester]

I'd just mount it to the side of your bed with some self-tappers, then run a low gauge wire to the frame in order to ground it.

 

[Drew Terril]

I run a hood channel mount for the Comet dual band on that's on my Titan. There are also hood mounts specifically made for those quad band antennas that, from what I remember, will allow you to fold it over to go into a garage, etc. I just don't recall any model numbers off hand.

 

[Mark Jack]

I've decided to bite the bullet and go with the Diamond K400S antenna mount. It should give me plenty of options for mounting locations and angles.

 

[Dan Robinson]

Many years ago I read about a chaser making a mount for a large antenna on the roof of a SUV using a Ryobi weed eater blade as a "washer" on the underside to distribute the load - apparently vehicle roof metal was at risk to "peel like a sardine can" with just the stock antenna hardware mounted.

 

[Mark Jack]

I know just from using a mag mount on my previous vehicle the area the magnet came in contact with was starting to rust pretty quickly, so I can believe that.

 

[B. Dean Berry]

About just shy of 100% of the time, I recommend a 3/4" NMO mount, dead center of a roof. If you're using VHF, it's one of the best places, ground plane-wise and for signal pattern. UHF Has a tendency to be a little less picky.

I do sort of chuckle when I see old-school CB guys with those nasty bumper mounts. Even if you run a ground cable, the ground plane reflection is going to be all sorts of jacked up, and the signal is going to be mangled.

 

[Drew Terril]

That Diamond mount is actually specifically designed for that particular quad band antenna, so it should be fine for that application.

 

[Matthew Sweet]

That's a tunable antenna and the mounting location will most definitely change your SWR. You'll need to experiment with a good mounting location and tune it to the desired frequency. Time to dust off the ol' MFJ. Last thing you want is to need high power for a distant repeater and find that not only are you falling short, but your radio is turning into a lava brick as well.

You don't really require a ground plane for this antenna if your primary usage will be 2m/70cm. The element phasing on 2m is the 1/2 wave section (2-5/8 on 70). A good vehicle ground will be required, which brings me back to my initial statement.

 

[Drew Terril]

If I recall correctly, that radio is limited to 50W on 2m (and possibly slightly less on 70cm). The downside of using something like an MFJ is while, yes, it will protect the radio, it won't enhance your transmission particularly well. If you can't hit the repeater without the MFJ, you probably aren't going to hit it with the MFJ. But on the plus side, you won't fry your radio if you screw up tuning your antenna