Antenna help

elkbow · Post by **elkbow** » Sun Sep 22, 2002 6:10 pm

Okay, bought a new Ford F250 Superduty Powerstroke, 4x4, Crew Cab, etc. I don't really want to drill a hole through the top of cab, so what I was thinking of doing....I installed a camper shell, topper, whatever you want to call it. I was thinking of mounting a piece of sheet metal to the inside of the shell roof. I would mount the antenna, NMO mount through the roof, only problem, it won't mount directly to the sheet metal, the fiberglass is too thick and the shell is built funny. I can get the antenna to mount (long story on exactly how). The sheet metal will act as a ground plane, so I will have to attach a ground from antenna to sheet metal and sheet metal to chassis ground.

Now, need some feedback here and thoughts, questions, idea's, etc. Don't be shy, tell me if I'm nuts or whatever, okay, don't tell me that, tell me what you think. Give me some ideas, possibly different antenna's, etc. I have a CDM1250 UHF, plan on also putting in a VHF......let me know what you think, will this work okay?

Al · Post by Al » Sun Sep 22, 2002 7:40 pm

You might consider using a thick stem mount(Motorola) that's designed for mounting whip antennas on heavy equipment with extra-thick metal roofs. The thick stem mount will accomodate roofs up to 2 1/2 inches thick, if I remember correctly. Your metal sheet ground plane inside the cab should work fine as long as you have a good bond from the coax shield to the metal plate(and it should be a minimun of 1/4 wave in all directions from the antenna assuming the mount is centered on the metal plate).

KG6EAQ · Post by **KG6EAQ** » Sun Sep 22, 2002 8:33 pm

You might also want to look into the Comtelco No Ground Plane Antennas. I've put a few of these on skiploaders and other construction equipment that has a plastic or fiberglass roof.

elkbow · Post by **elkbow** » Sun Sep 22, 2002 9:14 pm

Thanks for the info. I can't center the antenna on the roof of the shell. For some reason there is something built into the center of the shell, the extends down, so the only area I have is front or rear. Not sure I'll have 1/4 wave in all directions. There of course is a gap between the shell and the truck cab if I put near the front, near the rear would be worse, nothing off the rear of the shell.

I could possible do the extended mount and to through the center, depends where the ground is pulled from.

The ground won't come directly off the coax shield, but rather from the metal of the antenna itself......well truly I could pull off the shield if necessary, but it would be harder....of course connecting solidly to the metal of the antenna would be difficult.

Any location/source of getting the Comtelco No Ground Plane antenna's. I saw these listed somewhere, how well do they work, what is the principle. Thanks again for the info.

larrymedic · Post by **larrymedic** » Mon Sep 23, 2002 11:05 am

I was in a similar situation a few years ago. Here's what I wound up doing:

I went to the local HVAC guy and got a sheet of ducting to fit the inside of the shell. I could not mount centered, either, because I was mounting 2 different antennas, one on each side. Anyway, I had NMO mounts, and what I did was make a metal Z (actually rectangular, not angled like a Z but you get the idea) bracket with the head about 2" square, and the base about 2x4". I then drilled through the shell and through the metal plate. I then sealed the top with silicone sealant, and used large (>1") washers on the inside. As if this isn't enough, I also ran ground straps from both sides, down the inside of the shell, and attached them to the bed with screws. Great electrical, mechanical, and RF grounds. Moto shop was very impressed with performance. It was a little extra work, but you can get the z-plates made for a few bucks if you can't do them yourselt, and you can make the ground straps with the braid from coax. It's inside - it soesn't have to be fancy.

Good luck. Feel free to ask questions.
Larry

elkbow · Post by **elkbow** » Mon Sep 23, 2002 1:46 pm

Larry....thanks for the info, thats basically what I was thinking of doing, running an strap down to the plane and then grounding the plane. My only fear on the plane would be causing a feedback looping depending on the grounds and ground locations....another science just like antenna theory.

JohnG · Post by **JohnG** » Mon Sep 23, 2002 6:04 pm

Drill the NMO in the roof of the cab. When you take the antenna mount off to sell the vehicle, nobody will even notice the hole plug.

elkbow · Post by **elkbow** » Mon Sep 23, 2002 7:06 pm

i could always do that, anyone know of a motorola drill bit that strips the paint for ground at the same time it drills, or should I just use a hole saw if I decide to go this way and then remove the paint by hand?

YoChief · Post by **YoChief** » Tue Sep 24, 2002 12:43 am

Ahh, just mount the thing on the cab roof. I've had buyers actually ask me to leave the antenna in place when I sold the truck.

But if not, the thick-mount will get you through the camper shell as outlined above.

When I worked as an installer for a Motorola MSS we used to get vans in that had a fiberglass top added (Some were airport shuttle vans and some wheelchair vans used by an ambulance company) To get a ground plane we used aluminum duct tape stuck to the underside of the fiberglass roof. Use four six foot strips to make an eight pointed "star" and put the antenna in the middle of the star.

Worked great!

StanComm · Post by **StanComm** » Tue Sep 24, 2002 4:36 am

IMHO hole saws are the most barbaric of tools for working on a customer's vehicle.
I've had much greater success with the "UniBit" or Step Drill. It starts out at 1/4" and goes in 1/16" inch increments to 3/4".
Us it for drilling holes to run cabling as well as mounting the antenna. The thing's designed to work in sheet metal!
Scraping the paint? A good knife and a steady hand work great.
The ONLY time for a hole saw is if there's not enough clearance behind the surface you're drilling... and there might still be ways around that.
Stan

elkbow · Post by **elkbow** » Mon Sep 30, 2002 1:59 pm

I did it, I drilled the hole dead center on the top of my Crew Cab F-250. Hard part was trying to get measurements to have hole just behind dome light on inside. I couldn't go straight above dome because there is a drop down piece that the dome light assembly mounts to. Turned out perfect, put right behind dome assembly, ran cable to side, down seat belt channel along to behind rear seat where my remote mounted CDM1250 is located.

central150 · Post by **central150** » Wed Oct 30, 2002 11:56 pm

How hard was it to drill a hole through your roof? I may want to do it to my 2001 Sportage, but am weary as you were...

Tony

elkbow · Post by **elkbow** » Sat Nov 02, 2002 2:14 pm

It was simple to drill the hole, the hard part was pulling the headboard down. I only pull as much as necessary to stuff a rag up in the headboard to catch metal fragments from drilling the roof. I started with a tiny drill bit from the top and made sure I had the right position for the antenna, its hard to measure and 'eye' where exactly the hole needs to go. I got it right the first time. I finally stepped up to a big enough hole that my hole drill would fit. I used the stepping hole drill, titanium nitride coated, it put a perfect hole.

I had put electrical tape on the hole bit at the 3/4" mark so that I wouldn't accidentally go too far. I fed the cable in through the hole after taking some paint off around the hole in order to get a good ground. I ran a snake (coat hangar) up through the side of the headboard where the seat belt top position is and pulled the cable to the side. Mounted the antenna, ran the cable where it was not visible and now the only thing you can see is the antenna on top of the roof, no signs of anything inside, other than a remote mounted head of a CDM1250.

Tom in D.C. · Post by **Tom in D.C.** » Sat Nov 02, 2002 6:39 pm

Msg deleted...

Tom in D.C. · Post by **Tom in D.C.** » Sat Nov 02, 2002 6:39 pm

Elkbow:

Congratulations. You did it the right way. Now you can forget worrying about the antenna, and if it's working well or not, and just use the radio and enjoy life.

Tom, W2NJS

[...who drilled TWO NMO holes (one for a dualbander and one for a cellphone) in the top of his Outback this past summer...! Ugh! Just missed the front roof crossbar but managed to squeeze the NMO in anyway, thus again proving the wisdom of the saying, "Measure nine times, cut once!]
...in D.C.

elkbow · Post by **elkbow** » Sat Nov 02, 2002 7:28 pm

The radio works great with the antenna, big roof on the F-250 crew cab.

Its funny, no matter how many times you measure, it looks different from every angle, but I hit dead nuts my first shot.....first time for everything....

MT2000 man · Post by **MT2000 man** » Sun Nov 03, 2002 7:40 pm

elkbow:

I just had a remote mount "radius" mounted in my new Ford F-350 Powerstroke super cab as well, they, as well, drilled a hole right in the center of the roof.
You have any pictures of how your CDM looks?

The guys at bearcom were hinting my into buying a CDM.

elkbow · Post by **elkbow** » Sun Nov 03, 2002 11:11 pm

MT2000:

I'll contact you later in the week and then take some pics and send them to you. I am out of town right now, in Utah, cold as frozen sh_t.

I remote mounted it, the head mounted on the floor on the hump above my husky floor liner/hump line. the main unit is behind the rear seat.

MT2000 man · Post by **MT2000 man** » Mon Nov 04, 2002 3:21 pm

Ok, sounds good, I had mine mounted under the passenger seat.

Its gooding good for far, I just have to have it re-programmed again

Will · Post by **Will** » Sat Nov 09, 2002 11:12 pm

Elkbow, now all you need is a WillLock module for your truck's transmission. The WillLock locks up the tourque converter to greatly reduce the slippage and add some aditional braking comming downhill with your trailer, at your command.

elkbow · Post by **elkbow** » Sun Nov 10, 2002 8:46 am

'WillLock', what is that. That isn't 'Will' as in your name is it? Anyways....I'm looking at a few things, but parts cost money. I don't tow much, so engine or tranny breaking isn't a big thing, even though I live in New Mexico which is all mountains and hills. I am looking at the complete 4" exhaust and computer module for reprogramming, along with some pillar mounted gauges. Of course, then the 6" lift and tires.....cost, lift and tires about $2K, exhaust and chip about $1.5K....anyone got $3.5 to spare. As a matter of fact, there is a R2200 service monitor on ebay for a 'Buy It Now' of $4.1K (alittle steep for used, but like new), so if someone just doesn't know what to do with their money....

Will, did you get the kit I sent you. I sent a email, let me know on the other items, repeater/antenna related.

nmfire10 · Post by **nmfire10** » Sun Nov 10, 2002 1:08 pm

Will, you have a module for everything else. It wouldn't surprise me if you actually had something that did that.

Will · Post by **Will** » Mon Nov 11, 2002 1:52 am

Yup, the WillLock module for Dodge Cummins diesels is in production, even tho they are all hand built. They are available thru DoneRight Converters, in Portland, OR. Tony is the guy at DoneRight who makes the super tranny kits and toruqe converters.

Radio_Cowboy · Post by **Radio_Cowboy** » Mon Nov 11, 2002 12:36 pm

Ummm, but he has a REAL truck, will.....he's got a FORD...

-RC-
Ford Truck lover

Owner of ::

91 Full sized Bronco
79 F250 4X4
77 F250 4X4

elkbow · Post by **elkbow** » Tue Nov 12, 2002 5:25 pm

Yup....got a Ford....call it what you want, its a beast....although I hate to say it, but my Nissan that I still have is at 260,000 miles and still ticking.....

Will · Post by **Will** » Wed Nov 13, 2002 11:36 pm

The WillLock module for the Dodge/Cummins is about $120!!!!

The one for the Ford Power Stroke is in devolopement, should be about the same price. We are also working on a much less costly "chip" for the engine, too.

Antenna help

Antenna help

Tool to drill antenna holes

"Drill the roof!"

"Drill the roof!"

WillLock module