Using a standard car radio antenna to send and receive Citizens Band transmissions requires a few tweaks and measurements from a signal strength standing wave ratio meter. It is helpful but not entirely necessary to have an adjustable-height antenna that can be controlled from the passenger compartment of the vehicle. After mounting the CB radio a minimum amount of tools and time are required to get the best results.
Why Use a Car Antenna?
The main reasons to use your car radio antenna for your CB radio that is you have one less hole to drill into your car, you do not need to run two antenna wires and there is one less antenna to attract the attention of vandals. There are two different approaches to using a car radio antenna. If you are on a shoestring budget or if you prefer to have your antenna retract into the chassis of your car when parked or not in use, you can use your existing antenna. If you do not mind spending a few extra dollars for significantly improved performance, purchase an antenna designed to serve both CB and car radio signals to replace your existing antenna.
If you decide to use your existing car radio antenna you'll need a pair of wire cutters, some electrical tape and a few plastic cable ties to secure the new antenna lead out of sight. If you decide to replace the existing antenna with a combination model you'll need a wrench, a pair of pliers, electrical tape and possibly a set of fittings to attach to the end of one or both CB and car antenna wires. Both the necessary tools and the combo antenna can be found online or at your local electronics parts store.
If you are using the car radio antenna remove the car antenna plug from the back of the car radio and cut the wire about 6 to 8 inches above the plug that goes into the radio. Strip both ends of this coaxial cable to expose the shielded outer layer of conductor and the inner, copper-colored core about one-half to three-quarters of an inch. Splice these together with the coaxial antenna lead coming from the back of the CB radio. Plug both back into their respective receptacles. Tape up the splice and use the plastic cable ties to hide the wire under the dashboard. If you're installing a new combo antenna remove your old antenna and follow the instructions that came with the new combo antenna. Use the pliers and wrench to create a tight connection to the chassis of your vehicle.
Use a SWR meter to tune the CB radio for best broadcast and reception. Follow the enclosed instructions and you should be able to get reasonable signal strength from your dual setup. You may find that raising or lowering your old car radio antenna results in a slight increase in broadcast and reception capability. Remember to turn on your car radio to check the signal strength before hiding the spliced antenna wires.
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