How Do Power Antennas Work?by Don Bowman
A power antenna has a reversible reel motor in its base, and the antenna mast has a nylon cord attached to the bottom side of the antenna. This cord is wrapped around the reel and, as the reel reverses from one direction to another, it causes the antenna mast to either go up or extract back into its housing. On many of the power antennas on the market today, if the mast breaks, it can be replaced separately from the antenna housing.
How It Works
The power antenna has a wire for battery power and a ground, plus one more wire for actuation. This wire is the remote wire and is attached to the back of the radio in a port designated for the remote. There are two switches in the motor that shut the power to the reel off when the mast is fully extended and when the mast is fully down. All power antennas should be securely mounted on some part of the body so that it cannot move when it is actuated. This will prevent material fatigue. There should also be a fuse in line with the power to the antenna so that if the motor fails or the switch on the reel fails and it keeps running, it will not start a fire as it heats up. In many cases of failure, the switch on the real breaks or the nylon cord breaks and the reel will not stop when the radio is turned on. It just keeps spinning in an effort to raise the antenna, but because it is broken, the antenna is not going up and the motor will not stop running as long as the radio is on. In some cases, the motor will not stop running even with the key off depending on where it gets its power.
Fixing the Problem
If the mast breaks, call for the part and ask whether that particular brand is an external or internal repair. If it is external, all that is needed is to insert the nylon cord into the opening for the mast. Have a helper turn the radio on. The reel will catch the nylon cord and pull the antenna mast in. Some power antennas require removing the antenna, taking the side cover off and manually rewinding the reel.