Close proximity of NMO mounts

[4x4mike]

I need to clean up my roof and am looking to install NMO mounts for my 2m and CB. I've got a 4Runner with a sun roof and from what I can tell I can't mount an antenna behind the opening for the sunroof. When the window is open it appears it tucks into a sleeve of sorts and drilling a hole above it seems impossible let along getting an NMO in there along with some coax. I run a roof rack basket on the roof so I'm thinking I have to mount everything behind that as well. By the time I get to the rear of the vehicle there is about 10 inches of roof.

Is this enough room for 2 mounts? I know there is enough room for 2 little holes but what about having 2 antennas so close together? Currently both my antennas are mag mounts and one is near the sunroof the other is near the rear. As they are currently there is no audio interference between them but I don't have enough coax to put them close enough together to test where I want to move them to.

I was just hoping someone here might have a little input or experience to share before I drill holes in the roof. FWIW I run a 1/4 wave 2m most of the time and it's short and still. I have a 1/2 2m wave that I use just sometimes and it is much more flexible. From what I can find it looks like my only hope for an NMO CB antenna is a 5/8 wave which is in the neighborhood of 55" long. That's quite a bit longer than my 44" Wilson lil wil and I'm afraid it will clang around with the HAM antenna.

Again thanks for any input. Ideally someone out there would have some knowledge about NMO installs on a 4runner with a sunroof.

Thanks.

 

[xtatik]

Why NMO mounts? Why not mount the antennas to the rack or elsewhere on the vehicle?

 

[4x4mike]

I like the roof because it is out of the way. I've always got a Yakima rack with bike mounts. The other rack fits between the Yakima bars and very low to the roof and covers up most available sheet metal. While loaded down there isn't much room for antennas. Ideally I want the wires gone. They rattle, scuff up the paint, collect dirt, etc.

I thought about a lip mount for the hood but like using a short antenna on the roof and not having something low and fragile. From what I've read and seen most hood mounts require a longer antenna.

 

[1911]

NMO mounts are great; so easy to change or remove antennas in no time with no tools.

Physical interference between the two would just depend on the exact two antennas and how much the whips bend in the wind. But Tx on 2M will bleed loud noise all over the cb, if the cb is on at the same time, if that matters to you.

 

[4x4mike]

Thanks for the reply, this is what I was looking for. Most of the police cars around here have small antenna farms on their roofs and I was wondering if they have interference.

There would be times I have both radios on because on trails/trips folks use both. I think that if I was able to stick with the short 1/4 wave I would be good because it doesn't sway much at all. From what I've seen the longer 55" CB antenna would be the one whipping around.

I do like the NMO's a lot because, yes they are easy to switch antennas and take off. Currently I've got mag mounts and if I need to get in a garage or under a fallen tree I pull the mag and way it down temporarily.

Because my current setup is somewhat permanent I can't get the 2 antennas close enough to test for bleed over, etc.

 

[4RunAmok]

Physical interference between the two would just depend on the exact two antennas and how much the whips bend in the wind. But Tx on 2M will bleed loud noise all over the cb, if the cb is on at the same time, if that matters to you.

I do not have this problem with my CB and HAM, I can run them both at the same time, and there is no interference or loud noise through my CB at all.

My NMO's are roughly 2 feet apart, and they have banged into each other quite often on the trails.

 

[4x4mike]

Yours still clang at 2 feet apart? Mine would be much closer so I wonder if it would be a problem.

Maybe I'll install my rack basket and see if I can cut a hole in it for access to a whip. With the antenna off I could mount the basket and then mount the antenna later. The trick would be loading the basket and making sure I don't break the antenna yet still have room for everything I need up there.

 

[1911]

I do not have this problem with my CB and HAM, I can run them both at the same time, and there is no interference or loud noise through my CB at all.

You must have a better cb than mine; I have a Cobra 75 in one truck and a Uniden 78 (?) in the other. The Cobra is way worse than the Uniden I will admit. The only time I use either cb is when I'm in a trail group where not everyone has a 2M radio, but that is almost always in the back country and I have my 2M radio cranked up to full power to get out to a repeater and/or APRS digipeater. And full power almost always breaks through on my cb.

 

[4x4mike]

I too have the Cobra 75. I went out and tried it tonight and I get feedback on the 2m when keying the CB but not the other way around. Currently the antennas are both on the roof and a little more than 4 feet apart. The coax for the cb runs down the passenger side of the vehicle and the 2m down the driver side. Both are powered from a Blue Sea mounted behind the dash.

Looks like I'm going to have to do some more research because I don't want holes in my roof and worse interference.

 

[4RunAmok]

I'm running the Cobra 19 DX IV cb and Yaesu ham gear.

 

[SP Jon M3]

Have you thought about a lip mount on the rear hatch? I have two lip mounts, both the Diamond K400s. Attached to one is my 2m/70cm Diamond NR770HB and the other is my HF Yaesu ATAS-120. The mount does just fine holding up the heavy Yaesu. And this also separates the antennas.

EDIT: as I do a little more searching, can't find anyone using the K400 mount for CB. Not sure if this is because it can't be used for that, or if it's just that no has yet.

I noticed you used a fuse block for your radios. Make sure that the ground leads have a fused and direct connection to the battery as well. This is a must for the 2m/70cm radio.

I've attached an image, you can see both the antennas on the back of my 4Runner. I too run a Yakima basket and crossbars (factory crossbars are too flimsy) and there's no problem with opening the hatch with the antennas installed.