A CB antenna matcher or tuner can boost your radio's transmitting power while on the road. A tuner matches the antenna's impedance, or resistance to electrical flow, to that of the radio. The radio can maximise the transmission strength once the antenna system has been balanced. A small antenna tuner in your car can correct this interference, and increase the distance you can transmit and receive.
Cut three 6-inch lengths and two 3-foot lengths of electrical wire. Strip 1/2 inch of insulation from each end of the five wires.
Drill two 1/8-inch holes in a corner of the project box. Insert screws through the bottom of the box, with the threads facing inside. Tighten a nut and washer over each screw.
Drill a 1/4-inch hole through the side of the box near the screws.
Drill two 1/8-inch holes, 1/4 inch from the end of the PVC tube. Thread the magnet wire through the holes, and wrap the wire 120 times tightly around the tube. Twist the wire into a loop every 10 turns. Drill two 1/8-inch holes after the 120th turn, and thread the wire through the holes, locking it in place.
Sand the insulation from the loops, exposing the magnet wire. Place a dab of epoxy on each set of holes in the tube to secure the wires in place. Trim the wire short on one end of the tube, and leave 3 feet of excess wire on the other end.
Epoxy the PVC tube to the inside of the project box, near the screws. Make sure the wire loops are facing up.
Seat the variable capacitor in the project box, and determine a suitable location to drill a hole for the capacitor's tuning knob. Drill a 1/4-inch hole in the side of the project box for the knob. Epoxy the bottom of the capacitor to the inside bottom of the box, with the knob sticking out the hole.
Solder a 6-inch wire to the rear frame of the capacitor. Twist the free end of the wire around a screw. This will be the ground connector screw.
Solder another 6-inch wire to the solder tab on the side of the capacitor. Twist the other end around the empty screw. This will be the antenna connector screw.
Crimp the alligator clip to the end of the remaining 6-inch wire. Twist the free end of the wire to the antenna screw, and attach the clip to a wire loop on the PVC tube.
Crimp the centre element of the female coaxial connector to a length of 3-foot electrical wire. Thread the free end of the wire through the hole in the side of the box, and twist it to the antenna connector.
Thread the remaining 3-foot electrical wire in through the side of the box, and twist the end around the ground screw. This will be the ground wire. Tighten a second nut over both screws, securing the wires.
Thread the excess magnet wire out through the side of the box. Solder the end of the magnet wire to the centre element of the male coaxial connector. Solder the free end of the ground wire to the ground shield of the connector.
Plug the CB antenna wire into the female coaxial connector. Attach the male connector to the external antenna jack of the CB radio.
Tune and match your antenna to the radio by turning the capacitor knob and clipping different wire loops on the PVC tube.
Make sure the CB antenna is properly installed and grounded to the car's chassis. Once you find the wire loop that tunes the antenna most effectively, fasten the project box lid and use the capacitor knob only.