Note: The following instruction assumes you have a 'stock' CB Radio that has NOT been modified and you are NOT using any kind of external power amplifier:

If your radio doesn't have a built-in SWR meter (many do), then hook-up the SWR Meter by pluging the antenna cable into the output connector on the meter attaching a 3' piece of coax between the radio and the input connector of the meter.

Next, tune your radio to channel 20. If you have a mic-gain, turn it all the way counter-clockwise (off). Set the meter to "Calibrate," then key the mike and turn the calibrate knob on the meter to align the needle with the right-side of the meter's scale. Move the meter's switch to "Read SWR" and note the reading. On a stock CB, anything less than 2:1 is acceptable.

Most SWR problems are NOT the antenna being out-of-tune. CB antennas are pre-tuned at the factory. If your SWR is way off, you probably have a grounding problem due to corrosion or improper placement of the mount.