CB Radio Installation - Cobra 75WX - JeepForum.com
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post #1 of 5 Old 02-07-2018, 10:43 AM Thread Starter
djflyy
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CB Radio Installation - Cobra 75WX

Hey guys,

Continuing along with my write-ups of installs in the WK2 platform, I wanted to go ahead and post about installing a CB radio in the Grand Cherokee. I know there are a handful of other images throughout the forum, but when I went to do this I wasn't blown away by the information available so I did my best to thoroughly document the process for future installers to use as a resource. The WK2 is a clean cabin which required some serious thought for maintaining that level of appearance. When I go about installs I aim for an OEM+ look, which hopefully will be apparent here!

The radio used is the Cobra 75WX CB, and the antenna is a 2' Firestik NGP. I used an HD spring from Amazon to ensure the antenna stayed vertical at highway speeds.

As always, happy to answer any questions.

- Ryan

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'17 WK2 Trailhawk Expedition Build

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post #2 of 5 Old 02-07-2018, 10:45 AM Thread Starter
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When I first installed this, I had been planning to take the amateur exam and eventually install a 2m/440 system in the truck. Almost a year later now I have my amateur license, KC1HTW, but still maintain the CB is a great and easy form of contact with the majority of people off-road.

For better or worse, there's not a ton of information on CB installs in the WK2 models. A handful of photos here and there of antenna mounts, and a bit of HAM installs, but I figured I'd go ahead and of a more detailed write-up for anyone else that may need it in the future.

In order to maintain a clean look for the cabin, and to occupy as little floorspace as possible, I chose the Cobra 75WX unit. The system is pretty much contained in the mic itself, with scan and weather functions, and has a separate box that converts the PL-259 coax to the mic cable, also adding an external speaker 1/8" jack (the 75WX is known for a weak speaker, since it's contained in the microphone itself... for now, it'll be fine, but I'll eventually put a speaker under one of the seats for a little more oomph). I also chose a 2' antenna with the approximate knowledge that when mounted on a spring by the bracket, I would get the top of the antenna about 8" over the roofline. While this isn't fantastic for any antenna, it will give me adequate reception and will still maintain a clean OEM+ look (it'll also be able to fit in the lower bay of my garage if ever the need arose, and I can easily swap in a taller antenna for trips with the club.

From the images I found on google, it seems most people rivet or velcro a mic clip into the center console or on either side of the 8.4" screen, but I wanted something that was a little more easily accessible and didn't require drilling a hole in the dash or the tacky look of an adhesive. I started searching for a cell phone type mount specific to the Grand Cherokee, and discovered the ProClip Console Mount which was designed to mate up to the center console by the cup holders. They provide a small tool to pop up the console and get the lip of the clip underneath for secure mounting. It took all of 2 minutes to get this thing hooked up, including drilling out and screwing in the mic clip that Cobra provided with the CB.



ProClip Mount by 2180miles


ProClip Mount by 2180miles


Photos of other owners who have tailgate mounted antennas on the WK2 have shown them in two locations, 1 being drilled into the brake light assembly, and the other into the lower bumper below the brake light. In both instances the antenna is mounted into plastic, so I went ahead and ordered a NGP (no ground plane) antenna from Firestik. This is a special kind of antenna where the internal wiring is designed to work at locations that do not have metal ground planes, like motorhome fiberglass, on a motorcycle where the metal is minimal, and on boats. In this instance it worked perfectly for my plastic brake light.

I initially was hesitating to drill into the brake light itself but after removing the plastic pop rivets and taking the light off the Jeep, I realized that there was plenty of room to get a metal bracket on the back side of the mount in between the tail light's plastic. I cut up a small piece (1.5" x 1.5" , if that) of 18 gauge steel to provide a firm backing to the antenna bracket. Drilling it out to the same hole pattern as the bracket I was then able to use the self-tapping screws to get through the mount, plastic brake light, and metal on the other side. I painted the metal plate and put it front of my heat gun to speed up the drying. Putting this back onto the Jeep I was able to close the tail gate and check that there were no clearance issues between the two when it closed. Initially there was a little bit of rubbing (against the tail gate side plastic, not metal thankfully!) so I took the bracket to my angle grinder with a flapper disc and smoothed it down a bit to cut down on rubbing.



WK2 Brake Light Assembly by 2180miles


WK2 Brake Light Assembly Removed by 2180miles


Firestik Antenna Bracket w/ Metal Back Plate by 2180miles

'17 WK2 Trailhawk Expedition Build

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post #3 of 5 Old 02-07-2018, 10:46 AM Thread Starter
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Next up in the process was figuring out how to get the coax cable back to the CB itself. I had decided from the beginning that the CB controller box would live under the battery compartment lid (the battery on the WK2 is under the passenger seat... makes 12v wiring a breeze), so the coax needed to end up there. I fed the wire through the vents in the back of the trunk, then used my interior trim tool kit to lightly bend the trim pieces and push the wiring underneath. I moved from the rear pillar to the trim piece at the very back of the trunk, then around to the passenger side. I had to unbolt the cargo tie down to lift the right side of that trim piece up, but then was able to feed the wire down along the spare tire compartment to behind the rear bench seats. Moving to the rear passenger door, I fed the coax under the door trim and then under the passenger seat bracket and into the battery compartment. It took a while to get all of this done, using patience as I was petrified of breaking a trim panel on the brand new truck, but I managed to use all 18' of the wire without any coils or major stuffing of any spare wire... all good things for signal! It's also nice that the only time the cable is exposed is the 2" between the B-pillar and the front passenger seat, and the location where it passes through the tailgate weather strip.

Once that was done, I went to check in on my buddy Rob who had been going to town with the battery compartment cover. Cobra includes a nice grommet and mount for the wire, so we decided that instead of mounting the control box on the top of the compartment cover, we'd mount it underneath. Due to where the battery lives there was a lot of room to the left side, where the control box fit perfectly. Simple crimp-on ends were easily attached to the (+) lead of the battery, and we grounded it out to the seat bracket for a good chassis ground. Drilling out the compartment cover to run the mic control cable under the seat, we then threw the grommet in there and called it good. The nice thing about this CB is that the microphone can detach from the control box so if I ever need to get it out of the way for whatever reason, it's simple to do so.

Here are the photos of the wiring (I labeled the route in red) and the under-seat bracket and wiring.



Coax Routing Through Trunk by 2180miles


Coax Through Passenger Compartment by 2180miles


Coax Into Battery Compartment by 2180miles


Batter Cover Undermount by 2180miles


Battery Cover Install by 2180miles


Battery Cover Installed- Wire Quick Disconnect by 2180miles


After this it was a matter of getting the antenna assembly onto the rear bracket, and tuning it. While Firestik tunes their CB antennas from the factory, I find it's always best to re-do the tuning on the vehicle itself to find out how the environment and install have affected its signal. The yellow band at the base of the antenna in some photos is there to denote that is is a NGP antenna and will not function normally on a standard CB antenna install. Once tightened down on the bracket and the tailgate operation was tested a few times, we took the Jeep out to the end of a state park where marshlands surround the parking lot for quite a distance in every direction. This area provides an uninterrupted surrounding for the antenna to be tuned in, not affected by power lines, buildings, or other structures that can cut down on the reception and SWR readings.

After toying around with the adjustable antenna screw for a while, Rob and I were quite pleased to have the CB measure in at around 1.2 - 1.5 SWR at channels 1, 20, and 40. In my many experiences installing CBs in my Wrangler (I've used 3, 4, and 5' antennas, so I've done a bit of tuning) and installing them in dozens of friend's rigs, this was the quickest and cleanest install to SWR readings I've ever come across. I was quite pleased. I took some photos of the Jeep while we were out there, and let Rob mess around with the air suspension, dropping it into it's lowest settings (which I hadn't yet done) and raising it up to Off-Road 2 mode, it's highest setting.

After returning back to his house, packing up my stuff and leaving, he sat in the cab of his Tacoma and we did a range-test between our radios as I drove away. I knew going into this that the 2' antenna would be a limiting factor on range, but I was happy to find that I could hear him clearly and he could receive me clearly up to around 2 miles away as the crow flies. I had measured out distances from his house online beforehand to know which landmarks marked which distances. So, a few hours and about $150 and I have a solid CB set-up in the Grand, with a range that will do just fine for what I need it for.

Hopefully this will help someone out in the future if they are doing the same thing to their WK2.

Big thanks to Rob for helping out. Here are the final photos of it installed.


It's important to note, after a month I switched to an HD antenna mount, as the stock one was not capable of holding the antenna upright at highway speeds.




WK2 Antenna Spring Mount by 2180miles


WK2 Antenna Mount Bracket by 2180miles


Firestik Medium vs HD Spring by 2180miles





ProClip with CB Mic by 2180miles


Grand Cherokee CB Cabin Mount by 2180miles




Trans-Canada Highway by 2180miles


Washed & Waxed by 2180miles
**This last photo appears like the antenna is leaning... it's distortion from the camera lens Rest assured it's directly upright.

'17 WK2 Trailhawk Expedition Build

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post #4 of 5 Old 02-07-2018, 03:34 PM
metalhead
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Nice writeup. Installing a cb is on my to do list and this writeup will surely help.

1994 YJ (Gone)
2000 Grand Cherokee WJ (Gone)
2011 Grand Cherokee WK2
2012 Wrangler Unlimited JK
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post #5 of 5 Old 02-07-2018, 10:04 PM Thread Starter
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Quote:
Originally Posted by metalhead View Post
Nice writeup. Installing a cb is on my to do list and this writeup will surely help.
Thanks metalhead! Glad to hear it'll help... good luck with your install!

'17 WK2 Trailhawk Expedition Build

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