So, I'm looking to mount a couple of antennas on my F350. One will be for Ham dual band, the other for GMRS, though I may decide to use the 2nd antenna for portable HF instead.

I'm debating 2 options:
1) Bulletproof Diesel dual 3rd brake light mount
2) Roof mounted NMO mounts (I do NOT have the sunroof).

The BD mount is a clean and easy install but from what I understand, requires a non-ground plane antenna. I think that's OK for the VHF/UHF (there are a few available, and I think I may already have one), but I don't know if there are similar ones available that cover GMRS, and many HF verticals also require a ground plane. So, basically, with the BPD mount, I'm looking at an expensive option that limits my antenna selections.

For the roof mount, my biggest concern is any corrosion that may occur between the mounts and the aluminum roof due to the different metals. Should I be? Also, with the NMO mounts, are they 'sturdy' enough on the roof on their own, or do they need some type of backing plate? There were a few threads that mention these concerns, but no real definitive answers on them. If I go this route, I would probably have the mounts professionally installed (and would welcome any suggestions as to where to go in N. NJ to get it done).

Thanks for any thoughts/tips!

-Lee

 

I used to install commercial Motorola transceivers in cars and trucks. I could not begin to count how many NMO mounts I did. That being said, I have never installed an NMO on an aluminum body panel. It's been a long time, but if I remember the NMO of days past only had rather small "fingers" the held the mount in place against the panel material. As soft as aluminum is, I would be very hesitant about using an NMO. In my opinion a steel backing plate of some sorts is a must to distribute the load of the NMO to a larger area. As for the concerns about corrosion due to dissimilar materials, you might consider the grease like paste that electricians use when using aluminum wire in electrical panels.

 

The thickness of the aluminum roof on my '17 is greater than the thickness of the steel roof on my '11. With the stamped channels rigidity is not a problem.

Your NMO mount has metal-on-metal on the inside (dry!) side of the roof and the outside is o-ring on aluminum. Here in CO that answers the corrosion issue.

Where I live I may chose to use a repeater 8K feet higher than I am. For that reason I prefer a low gain antenna.

Suggestion for the hole-in-the-roof route: if you might use a garage, keep the antennas reachable on the drivers side for quick removal. That might include a hospital's garage. Don't get hung up on symmetry.

 

Is a bumper mount possible?

 

I have this though I haven’t mounted it yet so I can’t say how well it works.

 

I Have one of each on my 21 f 250 both the driver side and passenger side I have gmrs on pass and emergency services (154) on drivers side swr is 1.3 in band

 

I have the BD mount on my 250, I run 2m,220 and 440 analog/DMR through a Comet Tri band antenna with no issues. One of my concerns was whether the mount showed a ground, confirmed it did so the roof would act as a ground plane. But with that said, you loose the reflective end on the back side of the cab which would theoretically make transmitting directional, if I am loosing anything it isn't noticeable. When I am running our race frequencies in the 150MHZ (simplex) I have a dedicated antenna tuned for such that I swap out for, I can tell you my range is much further than those with the hood mount location.

The main reason I went with the BD mount vs drilling in to the roof was the stories of having the roof opened up like a beer can when either struck by a low hanging object or structure or (rare) an object airborne. Not saying if I struck something there would not be damage.

If you are running 2M/440 and GMRS ( which is 450 MHZ) you might be able to use one antenna and run an antenna switch.
I'm not sure how the "portable HF" thing would work out, that type of antenna is longer and heavier.

 

I mounted my ham antenna on drivers side cowl. Easily unscrews for washes.

 

Thanks, all for the replies. To address a few specifics comments:

Are you talking about dielectric grease? If so, isn't that conductive, and don't you want to prevent conductivity when dealing w/ galvanic corrosion?

Sounds like you're describing 'weatherproofing' and rust. Won't galvanic corrosion occur between two dissimilar metals regardless of whether water is present?

Not really. Not sure it's even possible, but I prefer to get the antenna up higher.

I really don't like those hood mounts. They look so 'tacked on', and I feel the antennas would be 'safer' up high (I had an uncle that had his K40 CB antenna stolen off the base back in the '70s...). If it was a work truck, I wouldn't care as much.

One each of what? The mounts the previous poster mentioned? Or the radios/antennas themselves? In either case, how does that help me w/o any details?

Thanks for that info, and you make good points. I was leaning towards the BD mount, partially because some of the things you mentioned, and you're reinforcing that.

Yes, some of the UHF/VHF antennas may overlap GMRS (I think many of the VHF-only single band ones do). The one I already happen to have is a dual-band UHF/VHF that cuts off at 148Khz, though (per spec)... But, I was thinking of starting off with 2 HTs in the cab, so I just need to run the coax up under the dash to start with. Later, I may mount a Mobile Dual-band radio (Yaesu FTM-400) in the truck, and either keep using the HT or go w/ a Midland Micro-mobile w/ all the controls on the hand mic as the GMRS. I can then either use a patch cable or just swap the coax from one or the other to connect my portable HF rig (currently a Yaesu FT919a). I have a screwdriver for the FT991a (ATAS-120a) that is a 'mobile' antenna, and should (in theory) cover 70cm to 40M bands, but it is a larger, heavier antenna that I may not want to leave on the truck all the time. They also make cheap whips ('ham sticks') tuned to specific bands, which I think use a 3/8" threaded base, but can be used w/ a NMO base w/ an adapter.

 

Rugged Radios has this adhesive backed steel plate that allows any kind of mag mount to be installed on an aluminum bodied truck. The diameter is too large to be placed between some of the ridges on the roof, but it can be made to work. About $20 when I got mine.

No holes. No corrosion. Easy stow at the car wash. A tree limb has already raked the antenna off the truck without damage to truck or antenna. That's why I like mag mounts.


no worry mag mount on an aluminum truck

 

[QUOTE=LMychajluk;20490892]Thanks, all for the replies. To address a few specifics comments:

Are you talking about dielectric grease? If so, isn't that conductive, and don't you want to prevent conductivity when dealing w/ galvanic corrosion?

Sounds like you're describing 'weatherproofing' and rust. Won't galvanic corrosion occur between two dissimilar metals regardless of whether water is present?



What I was referring to was anti-oxidant compound used by electricians. You would need to research it, but if your NMO mount is all brass an Anti-Oxidant Compound my not be necessary for aluminum and brass.

 

Dielectric grease is not conductive. That’s a myth as I understand it. I used it for my NMO mount on my Yukon.

On my last superduty, I used a hood mount. Kind of annoying having it in view. On my next, I’m not sure yet how I want to mount. Possibly a 6” Laird on the roof for GMRS and then a bed mount for a ham antenna.

 

https://en.wikipedia.org/wiki/Dielectric