External noise can be a distraction when using your CB and can cause your CB to be at times unusable. There are two ways noise can come through your CB radio: through the power supply or through the antenna. To stop the noise from coming through your antenna, there are a few things you will need to check in order to find the source of the noise. Once you have found the source, you can fix it.
Disconnect the antenna from the back of the CB. Turn on the CB radio and listen for the noise. If the noise disappears, you know the noise is coming from the antenna.
Check the connection from the antenna to the back of the CB. Make sure all the plugs are connected and there isn't any damage to the antenna cable's shielding. If there is a problem with the cable's connections or shielding, replacing the cable should remove the noise.
Check the ground coming from the antenna mount. If it is not a good ground, you could get noise into the system. If the ground appears good and there is still noise, move the ground to a new location on the vehicle's chassis.
Re-route the antenna's cable from the base to the back of the antenna if the noise is still there. The cable could be running too close to electronic interference and the cable could be picking up that interference. Move the cable away from the interference and the noise should disappear.