CB and Amateur radios with hood-mounted antennas

strogg

Watch out for this guy
Joined
Oct 31, 2020
Messages
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Location
North DFW
Current Ride
2020 F250 Lariat Tremor
Current Ride #2
2001 Ford Excursion, 2010 Ford Focus
Per the request of a fellow forum member, I decided to write this up. The ultimate objective is to install three radios. How to get there is a bit of a journey. This is more of a conceptual how-to than a direct how-to, though. There are many ways to skin a cat, as the saying goes. Unfortunately, with the aluminum body and my personal objectives of cleanliness, the many ways to get the job done turns into nearly none. Hopefully this helps others with their decision making on their own setups.

My parts:
  • Icom IC-2730a Dual Band Radio
  • Panavise Model 809 suction cup camera mount
  • Road King RK5640 CB Radio
  • Browning trunk mount NMO antenna base
  • Larsen dual band NMO antenna
  • Diamond K400 trunk mount 3/8-24 threaded base
  • Roadpro CB whip antenna
  • RG58 cable
  • 2x PL-259 male terminations for RG58
  • Miscellaneous mounting and cable management hardware
  • Low profile AM/FM antenna
Tools required:
  • 10mm socket wrench (that will open up every nut/bolt in the truck that you need)
  • Crescent wrench
  • Allen keys for the antenna bases
  • Heat shrink tubing (preferably minimum 3:1 shrink ratio)
  • Soldering iron
  • Heat gun
  • Wire cutters, strippers, crimping tool
  • Hot glue gun
  • Drill with stepper bit

Introduction

I originally wanted to setup 3 radios: A vanilla dual band ham radio, a dedicated APRS radio, and a CB radio. After experiencing some fun times with a dual band whip antenna on the roof of the Excursion (I hit a lot of things), I decided to put both the dual band whip and the CB antenna by the hood. The APRS can remain on the roof since it’s not as tall as the dual band antenna.

I was initially planning on having the power switched on by the upfitters, but I decided against it since one of the purposes of the radios is emergency services in the event I have no cell coverage. If I can’t turn on the truck, I’d have to physically bypass the upfitter relays somehow. It’s easier to just wire up the radios straight to one of the batteries than to figure something out in an actual emergency. Also, there are folks out there saying things are cleanest (no alternator noise) if the radios are hooked up straight to the battery.

After some research on how to put the roof antenna on, I realized my choices are pretty much limited to an aftermarket third brake light mount. The aluminum roof is basically paper thin. There’s a high likelihood of the antenna ripping off if it catches on some tree branches. I could put some steel plates underneath the roof as reinforcement, but that’s a lot of work. And mag mounts with the steel plates would look pretty bad with the cable needing to be routed into the cabin somehow. It would work fine if you don’t mind the wiring on the roof, though. Ultimately, I decided to nix the idea of the APRS radio until I get a bed cap. Then I’ll just mount it on top of the cap.

Speaking of bed caps, my plan on getting one is the reason I don't have the antennas on the truck bed, wall, or on a bed rack. Those are certainly better options that are more secure than the hood of the truck.

For those wondering, I don’t want to put the APRS antenna anywhere else other than on top of the truck. The APRS radio is pretty weak at 5 watts, and it is transmitting packet data, so it needs all the help it can get for transmission. Although it is useful by transmitting real-time GPS data, it’s not that important in my setup, so it can wait.


Parts/tools selection

I had a Browning antenna base laying around, and it works sufficiently. I still recommend the Diamond over the Browning, though. It is way better made.

For the antenna coax cables, many manufacturers are bundling RG316 rather than RG58 cable. There is much discussion on which is better for what and why, but in the grand scheme of things, it is easier to work with RG58, it is readily available everywhere, and it has half the loss as RG316. With such short runs, it’s not as imperative, which is, uh, why I chose RG58 over the thicker RG8x. Haha. Yeah, I clearly have a personal distaste for RG316.

For the antenna cable terminations, I ran the cables first, then terminated them myself for the perfect length. That way, it’s not a long run with several feet of cable coiled up by the radio. If you are not well adept with terminating antenna cables, then I suggest you get the cable pre terminated or stick with the RG316 runs that come with the antenna bases.

I chose the Larsen ham radio antenna because it is better constructed and much more flexible than the competition. The flexibility leads to less stress on the base, so it is not as prone to breaking.

As for the CB antenna, I actually got myself a Firestik FS2B, but I couldn’t find a light duty spring to mount it to. Well, I know I can certainly find one online, but I’d rather see it in person before purchasing, just to make sure it won’t be so stiff that it will snap the base off when I smack the antenna on tree branches. Until then, I’ll stick with the whip antenna.

Yes, there is a soldering iron on the list of tools. I like solder 100x more than butt connectors. If you are averse to soldering, then you can use a wire crimper and butt connectors to run the power. It’s up to you. If you want to invest in a new iron, I recommend going with a Weller or something higher quality. A cheap iron will make soldering a lot more difficult.

A heat gun is highly recommended. Heat shrink tubing will shrink a million times faster with one of those than with your wife’s blow dryer or a soldering iron tip. Make sure you get a quality one. The cheapo ones at Harbor Freight won’t last you very long.

I’m not going to list all the miscellaneous mounting hardware I used. It may be different from application to application. Just know that you’ll probably be visiting your local auto parts stores or hardware stores a lot as you get an idea of what you’re going to do. Hopefully, you can just raid your spare parts bin like I did with most of my stuff.


Running wires from the cabin to the engine bay

Before I dive into the actual installation, I want to talk about running the wiring from the cabin to the engine bay. I’ve thought of doing several things, from utilizing the pass-through wires on the passenger side to using existing holes. None of those are very fine options. The pass-through wires are very hard to get to. You’d have to be a midget to get any sort of meaningful access to those wires. And there are only four of them. It doesn’t even answer the question of how to get the antenna wires to the other side.

As for using existing holes, the one you’ll see brought up often is the main wiring harness right by the parking brake. Don’t bother trying. You have to be an acrobatic he-man to be able to undo that grommet coupling and pass your own wires through. That rubber is extremely tough. There’s also a hole supposedly under the carpet on the driver side that leads to the fender well. That is a heck of a route if you ask me, and there are lots of sharp, metal edges that can potentially cut through the wire jackets. Nah. That’s not a good option either. I ended up with the following:

IMG_20210104_183419.jpg
IMG_20210104_075426.jpg

I drilled a new hole next to the wiring harness on the driver side by the parking brake. The step drill makes short work of the aluminum. The grommet pops in very securely with a bit of coaxing, and the wires just slip right through. Once you’re done, you can seal it up with a hot glue gun, caulk, or even construction adhesive. Also, be sure to route the wires away from any moving parts; you don't want to mess up the functionality of your brake or throttle. Sorry for the quality of the second photo. I had to use a flashlight to illuminate the space.
 
Parts installation

Icom IC-2730a:


This radio has a separate controller that gets wired into the main unit with a registered jack connection. I decided to put the controller next to the rear-view mirror. I used a Panavise Model 809 suction cup camera mount and a bracket I had laying around to secure the controller to the windshield. The wire is run behind the headliner, then routed through the A pillar. The A pillar cover can be removed by popping out 2x 10mm screws hiding in the grab handle, then pulling it out. Note that there is a side curtain airbag behind there. It is a good idea to wrap the cord BEHIND the air bag and not in front. Just saying. Once past the airbag, you can snake the cable behind the dash.

To get behind the dash, you will need to pull the plastic knee bolster cover off, then remove the metal knee bolster behind it (4x 10mm bolts). The plastic pulls off with a bit of coaxing. Watch out for the tabs. They may break if you manhandle it too much. Removing the 10mm bolts should NOT be done with an impact tool. The nut clips Ford used are basically cheap sheet metal. I broke the two bottom ones while removing, but fortunately they’re not necessary for securing the metal knee bolster to the lower dash bracket. You will feel a lot of resistance when removing the bolts, as Ford put some thread locker on all four bolts.

The radio’s main unit is bolted down onto the lower knee bolster bracket. There are two holes perfectly spaced for mounting the radio with two angle brackets I got from the local hardware store. If your unit is sized differently, drilling holes would be a piece of cake. There is kind of a platform you can put the radio as well, so it won’t go anywhere.

The antenna for the radio is placed by the passenger seat corner. I wanted to put it by the driver seat since it transmits closer to the FM band than the CB radio does, but I realized that the 50 watt power is significantly more than the CB’s 5 watts. I also decided that my health is more important than those of the passengers (and presumably my future exes). Therefore, it goes on the passenger side. The coax cable and other wires I’m running across is routed through a wire loom zip tied to the cowl for a cleaner look. The antenna base puts pressure right on the lip of the hood, so it is pretty secure.

The power is routed through the firewall, and it hooks up straight to the driver battery via a 15 amp ATM fuse. I chose that style fuse because I wanted to use the same fuses the rest of the truck uses. The connections are made with a pair of spade connectors bolted onto the 10mm nuts on the battery terminal lugs.

Road King RK5640:

This radio is pretty large, and I can’t really think of a better place for it than in between my legs on the knee bolster. I drilled some holes on the knee bolster and mounted the radio to it with its existing hardware. The power is spliced into the same power that the Icom uses, so it’s one fewer wire that goes into the engine bay. It is a good idea to fuse that branch with a 2A fuse. The 15A fuse is a bit too high for the radio. The antenna wire also goes through the same grommet as everything else, and it terminates up on the driver side corner of the hood. The Diamond K400 uses 4 screws to hold the base into place along the lip of the hood for a very secure fit.

To wiring for the antenna base is exposed to the elements, so after attaching the appropriate spade connectors to the antenna base, I sealed everything up with a hot glue gun. It may not seem the most professional, but it looks more than good enough.

The radio has a built-in SWR meter for antenna tuning. If you use an antenna that comes “pre-tuned” it should be fine. Regardless, you’ll probably have an SWR of less than 2:1 anyway. Any more than 2:1 can cause damage to your radio gear. Only in extreme conditions would you find it above 2:1 on a plain-Jane installation. Despite that, it’s a very good idea to use an SWR meter to make sure everything is OK. You’ll only really need it for the CB radio (HF band). I’m willing to put money down that you won’t be running into any SWR issues with the VHF/UHF bands.

APRS:

Since I wasn’t installing it, I merely ran an 18 gauge wire from switch 2 of the upfitter relay into the cabin. It’ll simplify the installation when the time comes.

Stock AM/FM antenna:

Since the stock antenna will be right next to the ham radio antenna, it needs to be removed. You can’t have two antennas that close together. I replaced it with a stubby I got from O’Reilly’s. I made sure the top of the AM/FM antenna is practically below the base of the ham radio antenna. It will be fine if the antennas are not on the same plane. With the stubby, I could still receive all the AM/FM stations just fine for all 3 times I’ll use it in the next 20 years.


Post-installation pictures

Exterior shot with both transmitter antennas installed. You can also see the stubby AM/FM antenna next to the ham radio antenna.
IMG_20210104_075705.jpg

Interior shot with cb radio on bottom, ham radio controller by the rearview mirror, and the microphones hanging on either side of the steering wheel. Yes, there's plenty of room for my legs.
IMG_20210102_141809.jpg

Right side of bracket holding main ham radio unit down on the bottom knee bolster bracket.
IMG_20210101_081829.jpg

Battery connection
IMG_20210104_075550.jpg

Top view of the engine bay wiring. I could've done a much better job, but I was both tired and lazy at the time. Maybe I'll clean it up even more later.
IMG_20210104_075607.jpg

The antennas clear the windshield with the hood wide open.
IMG_20210104_075516.jpg
 
Parts installation

Icom IC-2730a:


This radio has a separate controller that gets wired into the main unit with a registered jack connection. I decided to put the controller next to the rear-view mirror. I used a Panavise Model 809 suction cup camera mount and a bracket I had laying around to secure the controller to the windshield. The wire is run behind the headliner, then routed through the A pillar. The A pillar cover can be removed by popping out 2x 10mm screws hiding in the grab handle, then pulling it out. Note that there is a side curtain airbag behind there. It is a good idea to wrap the cord BEHIND the air bag and not in front. Just saying. Once past the airbag, you can snake the cable behind the dash.

To get behind the dash, you will need to pull the plastic knee bolster cover off, then remove the metal knee bolster behind it (4x 10mm bolts). The plastic pulls off with a bit of coaxing. Watch out for the tabs. They may break if you manhandle it too much. Removing the 10mm bolts should NOT be done with an impact tool. The nut clips Ford used are basically cheap sheet metal. I broke the two bottom ones while removing, but fortunately they’re not necessary for securing the metal knee bolster to the lower dash bracket. You will feel a lot of resistance when removing the bolts, as Ford put some thread locker on all four bolts.

The radio’s main unit is bolted down onto the lower knee bolster bracket. There are two holes perfectly spaced for mounting the radio with two angle brackets I got from the local hardware store. If your unit is sized differently, drilling holes would be a piece of cake. There is kind of a platform you can put the radio as well, so it won’t go anywhere.

The antenna for the radio is placed by the passenger seat corner. I wanted to put it by the driver seat since it transmits closer to the FM band than the CB radio does, but I realized that the 50 watt power is significantly more than the CB’s 5 watts. I also decided that my health is more important than those of the passengers (and presumably my future exes). Therefore, it goes on the passenger side. The coax cable and other wires I’m running across is routed through a wire loom zip tied to the cowl for a cleaner look. The antenna base puts pressure right on the lip of the hood, so it is pretty secure.

The power is routed through the firewall, and it hooks up straight to the driver battery via a 15 amp ATM fuse. I chose that style fuse because I wanted to use the same fuses the rest of the truck uses. The connections are made with a pair of spade connectors bolted onto the 10mm nuts on the battery terminal lugs.

Road King RK5640:

This radio is pretty large, and I can’t really think of a better place for it than in between my legs on the knee bolster. I drilled some holes on the knee bolster and mounted the radio to it with its existing hardware. The power is spliced into the same power that the Icom uses, so it’s one fewer wire that goes into the engine bay. It is a good idea to fuse that branch with a 2A fuse. The 15A fuse is a bit too high for the radio. The antenna wire also goes through the same grommet as everything else, and it terminates up on the driver side corner of the hood. The Diamond K400 uses 4 screws to hold the base into place along the lip of the hood for a very secure fit.

To wiring for the antenna base is exposed to the elements, so after attaching the appropriate spade connectors to the antenna base, I sealed everything up with a hot glue gun. It may not seem the most professional, but it looks more than good enough.

The radio has a built-in SWR meter for antenna tuning. If you use an antenna that comes “pre-tuned” it should be fine. Regardless, you’ll probably have an SWR of less than 2:1 anyway. Any more than 2:1 can cause damage to your radio gear. Only in extreme conditions would you find it above 2:1 on a plain-Jane installation. Despite that, it’s a very good idea to use an SWR meter to make sure everything is OK. You’ll only really need it for the CB radio (HF band). I’m willing to put money down that you won’t be running into any SWR issues with the VHF/UHF bands.

APRS:

Since I wasn’t installing it, I merely ran an 18 gauge wire from switch 2 of the upfitter relay into the cabin. It’ll simplify the installation when the time comes.

Stock AM/FM antenna:

Since the stock antenna will be right next to the ham radio antenna, it needs to be removed. You can’t have two antennas that close together. I replaced it with a stubby I got from O’Reilly’s. I made sure the top of the AM/FM antenna is practically below the base of the ham radio antenna. It will be fine if the antennas are not on the same plane. With the stubby, I could still receive all the AM/FM stations just fine for all 3 times I’ll use it in the next 20 years.


Post-installation pictures

Exterior shot with both transmitter antennas installed. You can also see the stubby AM/FM antenna next to the ham radio antenna.
View attachment 13182

Interior shot with cb radio on bottom, ham radio controller by the rearview mirror, and the microphones hanging on either side of the steering wheel. Yes, there's plenty of room for my legs.
View attachment 13183

Right side of bracket holding main ham radio unit down on the bottom knee bolster bracket.
View attachment 13187

Battery connection
View attachment 13185

Top view of the engine bay wiring. I could've done a much better job, but I was both tired and lazy at the time. Maybe I'll clean it up even more later.
View attachment 13186

The antennas clear the windshield with the hood wide open.
View attachment 13184
Excellent write up!

Thanks!!
 
Great write up. Did you add a speaker on the ICOM?

Paul
 
Great write up. Did you add a speaker on the ICOM?

Paul

No, both radios use the built-in speakers. The cab is quiet enough to hear everything clearly. Well, as clearly as people can talk on the radio. Sometimes I'm not sure the people on CB are even speaking English.
 
Thank you, I'll be mounting a Kenwood TM-710G and probably a GMSR Radio in mine.
 
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