2015 f150 nmo’s install

[WX5812]

I am mounting 4 nmo mounts today.. the only one I have done so far is the center rear one. For the 2 in front of that one will the spacing that is pictured cause any problems in performance?

the rear center is vhf
The left is 220
The right is another vhf and the front center (not in picture) will be uhf

 

[FFPM571]

the spacing on the VHF's are way to close

 

[mmckenna]

That's difficult to answer.
The interference possibility depends on a number of variables, like transmitter output power, antenna spacing, the other radios ability to handle the strong adjacent signal.
The only way to know for sure is try it out with some temporary mag mount antennas and see how things perform.

Having a strong transmitter antenna close to another antenna can result in high levels of RF reaching the other radio. If too much reaches the soft, gooey, expensive bits in the receiver, it can damage it.

As always, more spacing is more better...

On my work regular cab F-350, I mounted a VHF and 800MHz antenna with about the same spacing, and haven't had any issues. Your milage may vary….

But like I said, more spacing = more better, but pay attention to ground planes. Figure out how much ground plane you need for each antenna (1/4 wave in all directions is ideal), then mount accordingly.

Rear Center VHF should be 19 inches in from the edges of the cab.
220 antenna should have about 13 inches all the way around it.
UHF antenna should have about 6 inches all the way around.
That might mean that the two VHF antennas go on the front/rear center line of the cab to give them the ground plane they need and the maximum spacing between antennas. Put the rear one 19" forward from the rear edge of the cab. Keep the front VHF antenna at least 19" back from the front edge of the cab.
Put the 220 and UHF antennas off to the sides, midway between the two VHF antennas.

You'll have to determine whats under the roof skin before you drill. It'll take some extra work and time, but it'll turn out better.

 

[mmckenna]

I'll add that sometimes you see installers that will just slap the antennas anywhere they want and fly with it.
They'll often assure you that spacing doesn't matter since they personally haven't experienced an issue.

It's an individual choice. You can do it right and back it up with some science, or like mentioned above, slap them randomly around the roof with more of a focus on looks rather than performance. Your choice. I've never regretted putting the performance needs ahead of the aesthetics. Some may disagree...

But it is complex. If you look at the roof of a CHP vehicle, you'll see a lot of antennas in a very small space. High end radios with good filtering work well in this application. Hobby grade radios with wide open filtering on the front end do not. Hammy radios with DC-Daylight receive capability usually have minimal filtering on the front ends and can suffer from damage.

There are some limiters that can be installed on rx only radios. I forget the name for them, but you can sometimes locate them on e-Bay. They'll usually block anything over about 1/4 of a watt, which tends to protect the scanner front ends. Those won't work on a transceiver.
External filtering could be added, but it gets expensive. Better to just do the spacing right the first time. If that's a crew cab F150, then you have plenty of real estate to work with.

 

[WX5812]

Thank y’all very much. I have adjusted them some and I now have 22”+ of spacing between them all and ground planes from edges are more that enough

 

[mmckenna]

Good deal. Looks like you are going to have a nice setup. Please post some photos when you have it completed.

A long time ago I set up my dad's truck. He had a commercial UHF radio and a dual band ham radio (VHF/UHF). I installed the antennas about 12 inches apart. After a while, he discovered that the VHF/UHF ham radio had gone deaf. Some troublshooting showed that some diodes in the front end of the ham radio had failed, likely from too much RF from the commercial UHF radio. Radio repaired, moved antennas farther apart, never had that issue again.

 

[AI7PM]

Thank y’all very much. I have adjusted them some and I now have 22”+ of spacing between them all and ground planes from edges are more that enough

I managed that as well on top of a 2013 and had no issues.

 

[WX5812]

Final result

 

[WX5812]

Some more pics

 

[WX5812]

All in all it wasn't too bad of a job. I went slow to make sure everything went smoothly....only get one shot at this. Once completed I soldered on silver pl259's and checked it all with a antenna analyzer. The only change I will make is the antenna in front center will be changed to a mono band UHF instead of the multiband bulky thing on there now. Its all I had with me. The radio in there now is an Anytone AT-5888UVIII tribander, and soon to be Motorola XTL2500 110W version VHF. I have not decided What else, but I would like to replace the Anytone with an yaesu FTM400 and have a mono band 220 along with the motorola.....Time will tell on that part. Thanks to everyone who chimed in. I believe I got this as best as I could while still making it look decent....The wife wasnt too interested but I showed her the rain caps that can be put on if need be.

 

[mmckenna]

Spacing looks good. That's similar to what I did on the regular cab work truck:

Turned out nice. I agree, get rid of that multiband monstrosity.

 

[WX5812]

mmckenna, Looks Nice!
Yes the enormous multiband antenna is just about worthless....Does ok on 700/800 but I wont have one in the truck. At least not right now....Now I'm on the next adventure of where to mount the xtl2500 I will add a picture of where the anytone tribander is right now......With all the mounts in place i can switch up antennas later if need be...Maybe even put a 900mhz in there also, it seems to be growing in my area.

 

[WX5812]

It’s a pretty descent spot, easy to see and controll. Not in the way of anything.

 

[mmckenna]

It’s a pretty descent spot, easy to see and controll. Not in the way of anything.

I can't tell from the photo, but does that truck have the center console, or is it the bench seat?

 

[WX5812]

I can't tell from the photo, but does that truck have the center console, or is it the bench seat?

It has a fold up middle console, not the full shebang.

 

[mmckenna]

It has a fold up middle console, not the full shebang.

OK, that's what my personal truck and work truck both have.

This is how I mounted the CDM-1550 in my personal truck. A piece of aluminum angle stock. There was a cubby hole on the bottom of the dash, and I mounted the aluminum on the top of that, and then bolted the bracket for the control head to the aluminum. Hole drilled in the back of the cubby hole for wire routing. Been that way since 2018 and it's worked well, including a lot of bumpy roads:

Did something similar in the work truck. Kenwood NX-700 VHF and NX-900 800MHz:

Also, lots of room behind the rear seat to mount RF decks. Just run a piece of uni-strut across the two seat bolts. I mounted a piece of 3/4" plywood to that, and mounted the radio, fuse block, shutdown timer, etc...

 

[mmckenna]

If you really want to go nuts, there's a lot of space behind the AM/FM radio screen. On my personal truck, I mounted one of the big Motorola speakers back there for the VHF radio. The big speaker provides really loud and crystal clear audio. Easy to hear even when running down the highway with all the windows down.

Pretty easy to get power from the battery. The big grommets in the firewall have a small nipple on the engine side. Cut off the end and you can easily run a piece of 6 gauge through for your main power feed. I installed a 60 amp circuit breaker on the firewall near the battery. 6 gauge runs all the way back to behind the rear seat and hits a fuse block to feed the radios...

The general layout of these trucks really hasn't changed much in quite a while, and the layout in the cab is pretty close between the F-150 and Super Duty's. I had a 2011 F-150 and it was really easy to move the install over to the 2018 F-350.

 

[WX5812]

Very Nice!! That seems like a perfect place for the Motorola O5 head to be mounted. As far as the setup behind the seat, that is brilliant! Great idea, I will see about doing the same. I like the idea of having thick 6ga wire going to the rear and having the radios connect to that via a breakout box or small fuse panel.

 

[mmckenna]

I like the idea of having thick 6ga wire going to the rear and having the radios connect to that via a breakout box or small fuse panel.

Makes life a whole lot easier to just pull one conductor and be done.
I picked up a local body ground off one of the studs the seats bolt to. Works better than a long return run.

 

[WX5812]

So you only have the positive wire going to the battery?