1. find an open location to park your vehicle. There should be no obstructions, such as trees or buildings, within 50 feet of your antenna. No one should be hanging out around the car, either. Make sure that you’re inside with the doors and windows closed to insure accurate readings
2. Connecting up the SWR meter. ( MAKE SURE YOUR CB RADIO IS OFF) CONNECT ANTENNA CABLE to the SWR meter in the connector marked “antenna” or “ANT.”
3. THEN use the PATCH COAXIAL CABLE to connect your CB radio and the SWR meter TOGETHER through the connection marked “transmitter” or "RTX"
(Now you are ready to measure the SWR on channels, 1, 20 and 40 Remember, throughout this process it's important to keep the microphone, meter and cable the same distance for each test.)
4. Set the switch on the SWR meter to “FWD.”
Check that connections are all hand tight.
5. Turn the radio to channel 1. (20 and 40 will follow)
6. Key the microphone (depress the mic button and hold it).
Turn the CALIBRATION knob on the SWR meter labeled so the needle is on “SET” mark.
7. While still keying or pressing the microphone button flip the switch on the SWR meter to the “REF” (REFlective).
record the reading given by your SWR meter and release the transmit key on your microphone.
NOW repeat this process for channels 20 and 40. Use steps 4 through 7
The goal behind tuning your antenna is to make these two readings as close as possible. Getting down to a 1.5:1 ratio or lower makes for an acceptable signal.
Adjusting the length of your antenna:
If the SWR on channel 40 is greater than on channel 1, your antenna is too long.
If the SWR on channel 1 is greater than on channel 40, your antenna is too short.
If your antenna is too long or short, it is necessary to adjust its length. There are several methods for shortening or lengthening an antenna many antennas feature a “tunable tip” that uses a small screw, some antennas may need to be cut to be shortened. Do so in 1/8" increments and then measure the new readings to decide if it worked. If not, adjust again