Click image for more information
Figure 1 shows the exploded view of a typical CB antenna mount. The threaded end of the antenna is screwed into the adapter once the mount has been fastened securely to the mounting bracket, bumper, tire carrier, or whatever you are using as your antenna mount support. The antenna coax coming from the radio is attached to the bottom of the mount using the SO-239 connector.
It is very important to note that proper assembly of the mount is necessary in order to prevent the antenna from shorting to the mounting bracket. The most common error I see this mount is assembled is that the insulated shoulder washer is placed on the bottom side of the mounting bracket. When this is done, the connector body remains insulated from the bracket while the threaded adapter is shorting to the bracket. The last time I witnessed this, the CB radio would create a squeal in the transmitted signal. It was so strong that it was virtually impossible to hear the person talking. I have seen this happen a couple of times and it is a common error. As you see, when the insulated washer is directly on top of the bracket, as shown in Figure 1, it prevents any of the other metal parts from touching the mounting bracket and shorting out the antenna.
The SO-239 connector must make good electrical contact with the mounting bracket. To ensure a good install, sand away any paint or power coat that is directly around the hole so the connector will make a good electrical connection.
Shown above is a homemade antenna mounting bracket made out of a scrap of metal, about 3/16" thick. I used two of the existing mounting bolts on my corner guards to secure the bracket in place. Round off the edges so no one cuts themselves on the bracket and you are good to go.
As of April, 2005, this is the current mount for my CB antenna. I did a slight modification to the rear mounting point of my driver's side TBT side slider. It works just fine. Same location as the previous mount but now just making use of what was recently added.