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Budget JK CB antenna mount, lots of pics

29K views 29 replies 15 participants last post by  Smitty4x4 
#1 ·
Mounting a CB antenna on the tailgate of a Jeep is not optimal by any means but many want it there for different reasons. Many variables can cause tuning issues. Grounding and antenna choice are the biggest issues. Always use a top loaded antenna such as a Wilson or Firestick that has the coil on the top. Antennas with coils on the bottom are too close to vertical metal that causes RF energy return to the transmitter (standing waves). Grounding the mount to the tailgate and grounding the tailgate to the body tub are key to getting the antenna to tune. It should also cure the intermittent problems for example one day you get an antenna warning light on the radio and on other days you don't. Even with the steps I will describe in this write up expect the SWR to be between 1.2:1 to 1.3:1. With alot of experience and trial and error a 1.1 is possible but I have only done that once. I usually get around 1.2.

Using a truck mirror mount this is how I built a budget mount for the rear of my JK.

The mount will make contact with the glass of a hard top if simply mounted on the brake light riser. I took a small amount of metal off of the curved section of the mount. Next remove the brake light from the riser. Cover the tailgate with towels to protect the paint. I used a 4inch angle grinder to cut a slit in the riser.

The mount will be bolted to the inside of the riser but the curved section will keep the mount from mounting flat.

Use the mount to determine the lower section to cut out.

Cut the relief hole and check for fit.



Make sure that there is enough play that you can level the mount with a small torpedo level with the vehicle on a level surface at least side to side. Front to back will be adjusted later.

Drill ONLY one hole and install the bolt. Only snug it down so you can rotate with a gentle tap.


Before drilling/installing the second bolt make sure the mount is level side to side. Failure to do this will most likely result in a leaning antenna. A small twist at the base will be exagerated by the antenna.

Finish the other two bolts and install the antenna on the base.

The mount should clear the glass. More clearance will be added later.

PROBLEM! Easy to solve.

Install 2-3 washers between the mount and the riser ONLY on the top two bolts.
 
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#2 ·
I used two washers per bolt and may do three later. You can now see more glass clearance and the antenna doesnt hit the wiper.



Now install a ground wire to the mount. I used 12ga wire. I try to use 12ga or larger wire when grounding. However wire larger than 12ga may cause problems later in the install.

Remove the panels on the tailgate in the direction shown. You will damage the tabs if you pull the wrong side first.


Route your wires through the brake light gromet. You'll want to trim the gromet to allow the wires to pass with out laying on the metal then protect it with some RTV .

Carefuly use a small sharp object to release the latch on the zip tie and pull it free without damaging the mount or latch.

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Remove the trim panel on the right side of the cargo area.


Undo the zip ties here the same way.

Remove the tape from the factory wires and route the antenna wire through the loom.

Route the ground wire through and leave slack to ground the tailgate in the compartment on the right.

 
#3 ·
Now clean up the outside with some wire loom and use tape on the ends. I use quality Scotch brand electrical tape or equivelant. The no name stuff has cheap adhesive and I like my install to last. Don't stretch the last wrap and cut the tape, dont pull tear it. It works but as the tape slowly contracts back to original shape the adhesive area left will attract dirt and look bad. I go one step further and paint the end of the tape with a liberal coat of liquid electrical tape all the way around the last wrap. It doesnt have good enough structure to hold the loom but it does a good job of keeping the tape from unwraping and doesn't attract dirt once it's dry.

Zip tie the cables to the factory wires near the factory ties. If you want it to look real good do it the way the next few steps show. Wrap tape where the factory does and try to replicate thier mounting. I usually take pics to remember where to put tape and position the wires.

We carefully opened the zip ties for a reason. Cut the left over tie off and make sure to leave the latch and mount in tact.

Try to find a zip tie the same width and make sure to insert it into the latch in the same direction.


Retape the end of the loom and close the zip tie.

Connect the end of the ground wire and secure the loom in the other two zip the same as we did the other.

Button up the panels and clean up. The rest of this install will be covered in a later post.

 
#5 ·
This is a really clean install. I love the mount and would do it myself but have a Wurx bumper on the way in a week or two. Now I'm looking or some other mounts but don't plan to use the radio much so I'm torn between a 3' or 4'. Would like to keep clean lines. Where did you mount the CB radio?
 
#9 ·
The main goal is to bond the tail gate to the chassis. That is more important than antenna to tail gate. As soon as I get some proper braided ground strap I will do a full post on bonding (grounding). RF signal grounds are different than electrical ground. The hinges of the tailgate can cause poor bonding to the chassis. Bonding in very poor layman's terms is kinda like attempting to get the tailgate and chassis to perform as one piece of metal signal wise. Some tailgate antennas will work fine without it. I install the antenna then check for problems. In my case the meter jumped around when the tailgate moved or flexed. It went away with the wire so I left it temporarily in order to use it until proper bonding could be done. Wait until the equipment is installed then check. Hopefully I'll have the bonding post done by then.
 
#15 ·
There is a difference between grounding and bonding. I had in issue with the SWR jumping around while driving. The ground wire I installed is actually not even the proper way bond the chassis. I did it to test where my problem was. In this case the tailgate was not bonded well to the chassis. This is a common problem with Jeeps. Poor bonding affects the RF ground plane. The proper way to bond the tailgate is with a braided strap which I intend to do eventually. The problem is that the wire has worked so well that I have not been motivated to install one.
 
#25 ·
Well, that is a tough question. It all depends on what your requirements are and what kind of performance you need. Are ascetics a concern? The optimum would be a large flat metal plate fabricated to cover the roof of the Jeep then bond the plate with a series of braided steps to the chassis to create a proper ground plane. We know that isn't reasonable so Jeeps always tend to be a question of acceptable compromise. I have always mounted mine to the rear of the vehicle. Preferably to the center of the tailgate. The rear mount is used when looks are a primary concern. We accept the fact the the ground plane will be forward of the antenna which means we will have better transmit and receive distance for stations in front of the Jeep. Ideally the ground plane would be a circle with the antenna in the center. When an antenna is mounted in the center of a standard vehicle, the RF field, if we could see it, would appear oval with the longer sections extending from the front and rear of the vehicle. Without installing a large plate, the next best place is the center of the hood. After that would be to the side of the hood (aftermarket mounts are available for this). Then the front of the hood (best signal will be to the rear). Front and rear mounts will perform similarly. I prefer the rear as stated earlier and I get acceptable results. Sometimes tuning is tricky but it works in the end. With a standard CB, I can still talk with Jeeps that are at least 4-5 miles behind me. Maybe further but I have never tested. On the highway I have talked to vehicles 10 miles ahead. Of course open flat sections of highway will always yield better than deep woods and mountains.
 
#27 ·
Keep in mind that when using a spring, the length of the antenna is effectively extended. This can cause issues with tuning. I use Wilson flex antennas with no spring. I have yet to break one. If you experience tuning issues remove the spring and recheck.
 
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