Antenna mounting on a Ford Bronco ::IE fiberglass install on

Post by **Grog** » Fri Mar 11, 2005 12:22 pm

I have a 95 Bronco that I'm wanting to install several antennas on. Has anybody installed through the fiberglass roof? If so, how did you run the coax? Did you install any metal on the roof for a stable platform?

If I'm limited to the steel roof area, how could I put three antennas up there? The middle would be either a 5/8 2mtr or a 2mtr/440 antenna. The other would be a hi-gain 800 scanner and a VHF 1/4 wave or multi-band scanner antenna. Most of the time the middle antenna would be the only transceiver antenna. Sometimes I'd have to run an HT and replace one of the other antennas.

If I were only mounting on the steel, would it be best to install all three mounts side-by-side, or with the main antenna in the middle on the "hump" with the others halfway to the front & the sides. I'll try to draw a pic & attach it later to explain what I mean.

Thanks again everybody

P.S. Any Bronco install pics are welcome

KG6EAQ · Post by **KG6EAQ** » Fri Mar 11, 2005 1:38 pm

This is my Bronco. Rear is for a scanner when it's in, middle is 1/4 UHF and the front is 2.4ghz for the laptop. Btw, the truck is for sale if anyone is interested in it. '94 with 136k on the dial.

You can mount your scanner antennas on the fiberglass, just get some metal and make the needed groundplane.

kb0nly · Post by **kb0nly** » Fri Mar 11, 2005 1:40 pm

Although not a Bronco, i did do a through fiberglass install once on a boat. I used a 3/8" through hole NMO mount and a small sheet of aluminum. Drill the hole through the roof and a matching hole in the aluminum or steel sheet and put it all together with the metal sheet on the bottom side of the roof to form a ground plane for the setup.

The metal also provides a bit more strength when the mount flexes from the antenna whipping about. I used a bit of liquid nails adhesive to secure the metal sheet to the underside of the roof. Then button it up by replacing the headliner or trim panel, etc, and its a nice clean install.

The reason i prefer the 3/8" NMO for this situation is because its a smaller hole first of all, and also the 3/4" hole mounts only grab a small area around the edge of the hole and on the fiberglass will cause cracking and breaking. The 3/8" mount has more contact area to work with. Also, if you ever drill through fiberglass use a countersink bit, or a drill bit one size larger than the hole to chamfer the top edge of the hole just a bit, like when you countersink a screw when doing wood work, this keeps the gell coat from cracking and spidering out from the edges of the hole.

Post by **Grog** » Fri Mar 11, 2005 6:50 pm

The cracking and spidering is exactly what I'm worried about. That what's kept me from doing the fiberglass install so far. It's a 95 with 134k miles and I'm gonna keep it until the engine & tranny blows, then I'll rebuild them and run it til it blows agaon

Thanks for the pics, any other advice or pics are welcome.

kb0nly · Post by **kb0nly** » Fri Mar 11, 2005 11:10 pm

The spidering of the gell coat is the worse thing about dealing with fiberglass. But, on the boat installs i have done, anything that requires going through the gell coat, be it a screw, bolt, antenna mount, etc, if you countersink the hole which puts a chamfer on the edge of the gell coat around the hole, you run a lot smaller chance of it happening.

Not to say that it will never happen with age! But then it could always be sanded and touched up down the road if necessary.

robertisby · Post by **robertisby** » Sun Mar 13, 2005 11:13 am

The problem with sheets of mettal for the gournd plane is the typical inability of the fiberglas to flex properly or the sheet metal to do the same and it causes some SERIOUS dmage to the rooftops.

It has been my experience, and a success story so far, is go to any of the industrial HVAC people and get the REAL duct tape. THis is usually three or four inch wide rolls with a real gummy adheasive. Use a standard 3/4" thick roof mount, a VERY sharp 3/8" drill bit and now you have a good ground plane (might want to use a 1-1/2" washer too) and install the NMO mount through the tape, through the roof. In addition to this, a "No-Ground Plane" antenna like a Maxrad will give you great results. I have done this on fiberglass ambulances for YEARS and they are still working well.

Post by **Grog** » Sun Mar 13, 2005 5:08 pm

This is something I'll leave to a radio shop to do if I decide to do it. I'm still debating if the extra costs (of fabbing stuff) and the added risks are worth it. I'm inclinded to say no at this point.

I'll probably just go with the three on the roof. I'd love to do the three-in-a-row front to back install, but the lower freqs I'm using should have more spacing. I'll have to do some mesuring tonight

Radio_Cowboy · Post by **Radio_Cowboy** » Mon Mar 14, 2005 10:38 am

I have a 91 Bronco Full size, and a 96 Bronco Full size. In my 91, I have a UHF and a VHF 1/4 wave on the roof with NMO mounts, and a 5/8 VHF on a "L" bracket on the hood for the scanner antenna. My 96 just has a dual band ham antenna and a VHF 1/4 wave on the roof at this time. I don't even want to mess with the fiberglass roof.

-RC-

Post by **Grog** » Mon Mar 14, 2005 9:17 pm

How are they mounted? Front to back, or side by side? just wondering how they're set.

Do you have any pics?

Radio_Cowboy · Post by **Radio_Cowboy** » Tue Mar 15, 2005 9:42 pm

Sorry, I don't have any pic's.....but mine are a lot like KG6EAQ's. I have the 1/4 wave VHF on the metal part just before the Fiberglass, and I have the dualband on the middle of the roof directly in front of the VHF. And of coarse, the L bracket VHF is on the hood. It works ok for the scanner, and in a pinch, I can use another VHF radio on it if Needed. Not as good as on the roof, but it does work.

-RC-

Post by **Grog** » Wed Mar 16, 2005 10:23 am

OK, thanks. Running front to back, I may run two dual-banders (on for my scanner, one for the 2mtr) and a 800 in front. I'll use L-bracket mounts for spare/extra eqipment.
When It's time to get this done, I'll post pics of the whole process.