The SWR Meter and the Proper Way to Tune Your CB Antenna
Happy New Year! You’ve purchased your CB radio and CB antenna. What’s the next step? Before you receive or send your first transmission, you need to tune the CB antenna.
This step plays a big role to get the desired broadcast signals. Without proper tuning, your voice won’t reach the desired audience. Furthermore, regardless how powerful your CB radio is, incoming broadcasts won’t be as clear, especially when coming from far distances.
The Tools for Tuning
Fortunately, tuning your antenna is not a difficult process if you have the right tools. Basically, you require a CB Radio and a Standing Wave Ratio (SWR) meter. This piece of equipment, either standalone or built into the CB, determines if the resistance from the radio to the antenna are acceptable. The higher the SWR or resistance the worse you’re your rig will perform.
Once you have the tools, follow these steps to ensure CB radio operations with clear, far-reaching signals.
- Determine a place to put the antenna. Make sure the line of sight is clear of obstructions like trees or buildings.
- If your CB radio has a built in SWR meter, move to the next step. If not, place the standalone meter between the antenna and the radio. Disconnect the antenna’s coaxial cable from the back of the CB and reconnect it to the area in the back of the meter marked antenna or ANT. Then, connect the jumper coax from the meter to the space in the back of the CB marked transmitter or XMIT.
- Measure the SWR on Channel 20 if your SWR reading is below 1.5 then you are all set. If it is not below 1.5 you will want to test the SWR on Channel 1 and then Channel 40. Make sure to note what the SWR reading is on each channel.
- Set the switch on the meter to FWD and turn the radio to a channel that’s clear of transmissions.
- Press and hold down the microphone’s talk button (aka, keying).
- Turn the knob on the meter labeled SET or ADJUST until the needle reaches the end of its range.
- While still keying the microphone, flip the meter switch to the REF or SWR position.
- Quickly record the reading and release the microphone’s transmit key.
- If your reading is lower on Channel 1 then 40 the antenna should be electrically lowered. If it is lower on Channel 40 then it needs to be lengthened electrically.
The goal of these tests is to make the two readings match as close as possible. Measurements within the 1.5:1 ratio or below (the green zone) generate a clear broadcast signal. A ratio between 1.6:1 and 2.0 means the radio is safe but operation is not optimal.
If the meter reads 3.0 on one or both channels, further SWR tuning is required. If not, radio waves can overheat your CB radio components.
Take note of the above procedures and SWR measurements to successfully tune your antenna for optimal performance and transmission.
We recommend the Astatic PDC7 CB Radio Test Meter with Jumper Cable, but please feel free to contact one of the specialists at CB Radio Supply If you have any questions.