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How to Do a VSWR Test

The power that comes out of a transmitter, such as from a CB radio or an amateur "ham" radio, travels from the radio along a transmission cable to the antenna. If you do not "match" the antenna electrically to the radio, some of the power reflects back to the radio. This wasted energy is called a standing wave. An SWR meter measures this voltage, or VSWR. Ideally, a reading of 1:1 is the goal. A meter reading of 1.2:1, for example, indicates that the maximum standing wave's amplitude is 1.2 times stronger than the minimum wave.

Things You'll Need

CB radio
Antenna with coaxial cable and end connector (PL-259)
SWR meter
Short piece of coaxial cable with PL-259 male connectors on both ends

Instructions

- 1
  Unscrew a PL-259 connector and cable from the antenna jack on your CB radio (labeled "Antenna" or "ANT").
- 2
  Screw the connector and cable onto the "Antenna" or "ANT" jack on an SWR meter.
- 3
  Connect one end of a short piece of coaxial cable with male PL-259 connectors on each end onto the "Xmitter" or "Transmitter" jack on the SWR meter, and connect the other end onto the "Antenna" or "ANT" jack on the radio.
- 4
  Close the doors of your vehicle if you are testing the VSWR of a mobile radio.
- 5
  Tune the CB radio to channel 19 --- about the center frequency of the CB's range.
- 6
  Push the switch marked "Adjust" or "Set" on the SWR meter to the "Set" position.
- 7
  Slide the switch marked "FWD" (or "Forward") and "REF," (or "Reference") to the forward position.
- 8
  Depress the "Transmit" button on the microphone, and hold it down while turning the SWR meter's adjustment knob until the meter's needle aligns with the indicated set mark on the meter's faceplate.
- 9
  Move the" FWD/REF" switch to the "REF" position. Continue to hold down the transmit button. The meter's reading will indicate the VSWR.

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