How To Tune A CB Radio: Step-By-Step Instructions

1. Start by finding a suitable parking spot for your vehicle. Ensure there are no obstructions, like trees or buildings, within a 10 to 15-meter radius of your antenna. It's important that neither you nor your friends are hanging around the car. Once inside, make sure all the doors and windows are closed for an accurate reading.
2. The next step is connecting the SWR meter. Begin by disconnecting the coaxial cable from the back of the radio. Then, reconnect the end of the cable that goes to the antenna to the SWR meter's "antenna" or "ANT" connector. Use the jumper lead to connect your radio and SWR meter through the "transmitter" or "XMIT" connection.
3. Now, you're ready to measure the SWR on different channels. Remember to keep the microphone at the same distance from the meter for each test.
4. Set the switch on the SWR meter to "FWD."
5. Tune the radio to channel 1.
6. Press and hold the microphone button (key the microphone).
7. Adjust the knob on the SWR meter labeled "SET" or "ADJUST" until the needle reaches the desired position at the end of its range.
8. While still holding the microphone button, switch the SWR meter to the "REF" or "SWR" position.
9. Quickly record the reading displayed on the SWR meter and release the transmit key on the microphone.
10. Repeat this process for channel 40. Follow steps 4 through 9.

The goal of tuning your antenna is to minimize the difference between two readings. Achieving a ratio of 1.5:1 or lower ensures a satisfactory broadcast signal. Before adjusting the antenna length, it's important to understand two key points:

• If the SWR on channel 40 is higher than that on channel 1, your antenna is too long.
• If the SWR on channel 1 is higher than that on channel 40, your antenna is too short.

If your antenna is too long, it's necessary to reduce its physical length. Different manufacturers offer various methods for shortening an antenna, so consult the owner's manual for specific instructions. While some CB antennas have a "tunable tip" that can be adjusted with a small screw, others may require cutting. If cutting is necessary, do so in 1/4" increments and recheck the SWR readings to track your progress.

On the other hand, if your antenna is too short, you'll need to increase its physical length. In most cases, a lack of ground plane causes the antenna to be too short. Many modern antennas have a built-in method for adding length. Alternatively, adding a spring is another valid option.

When installing dual antennas, it is important to adjust both antennas equally each time. Initially, set the tuning screw to either its maximum or minimum position to ensure both antennas are the same length.

Based on your SWR readings, make equal adjustments to lengthen or shorten BOTH antennas. Measure the SWR again and continue to make incremental changes, aiming for consistency between the antennas.

SWR readings below 2.0 indicate safe radio operation, although transmission may not be optimal. If readings on these channels exceed 3.0 or fall within the red zone on your SWR meter, avoid using your radio. Address the issue before attempting to operate it.