How to Tune a CB Radio Antenna

If you have a CB radio and an antenna, you have to take precautions with the SWR (Standing Wave Ratio) so that you do not damage the CB radio itself. The standing wave ratio pertains to the channel frequencies and the antenna length. The last thing you do is put up an antenna, hook up the coaxial to the CB and turn it on to begin talking. Learn how to tune a CB radio antenna before you start communicating on your radio. If you do not follow these steps, your radio is not protected from damage and may not work the way it should.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• SWR meter (if your CD radio does not have a built-in meter)

1. Mount the antenna and run the coaxial cable to the CB radio. Use a SWR meter to check the standing wave ratio. If the radio has a built-in meter, you will not need an external SWR meter. You can hook the coaxial to the back of the radio. If you need the external SWR meter, hook the coaxial cable to the input on the meter and run the patch cable to the back of the radio.

2. Pick a channel close to the low side of the radio frequencies. If no one is on channel one or two, choose one of these. Key the microphone button. As you do this, look at the SWR meter to see what the reading is for this low channel. The ideal reading should be below 1.5. If it is, you are in great shape. Then move to a higher channel such as thirty. Repeat the SWR check. If this reading is below 1.5 as well, your antenna is just right. If the SWR is high, move on to step 3.

3. Adjust the CB antenna length up or down. Every antenna is different, but will either have a setscrew to hold the antenna in place or a set of locking rings that hold the antenna in place. If the SWR is high on the low channel, make the antenna slightly longer. If the SWR is high on the upper channel, make the antenna shorter. Follow step 4 to lengthen or shorten the antenna.

4. Unlock the locking rings by winding in the opposite direction. If you need to lengthen the antenna, loosen the top ring and move up one turn, then move the bottom ring up and lock. If you have a setscrew, loosen and use your other hand to raise the antenna up slightly and then tighten the setscrew and lock in place. If the antenna needs to be shortened, do the opposite.

5. Check the standing wave ratio once more as described in step 2. If you still have a standing wave problem, repeat step 4 until you have a good standing wave ratio on both the lower and upper channels.

Tips & Warnings

• When you are checking the SWR, never have your hand on the antenna. This will interfere with the reading. Sometimes, you may have to move the antenna if you cannot get a good reading after trying to lengthen and shorten the antenna.
• Never check the standing wave ratio on channel 19.