How to check SWR

Technical Support

"How do I check my SWR?"

This is a question I get asked everyday. People seem to think it's a complex operation. This is not rocket science, it's easy, anyone can do this if you have a SWR meter. You can use the meter that is in the radio if you have a SWR feature or you can use an external SWR meter. The external meters can be found just about anywhere and usually cost around $20 to $30. The procedure is basically the same on both meters but the terminology may be a little different. To keep things simple we will describe both separately.

This page has a lot of pictures and may take a few minutes to load

**NOTE**
It is VERY important to understand that the SWR meter WILL NOT CHANGE YOUR SWR! The meter is a source of measurement ONLY. Look at it like a tire pressure gauge, it only tells you what the pressure is, it doesn't change the tire at all. All adjustments need to be done to the "Antenna System" (Antenna, Bracket, Mounting assembly, Cable, and even Location)

Using Built in SWR meter
Using External SWR meter
Troubleshooting tips
Fine tuning

How to Check SWR with the radios built in meter

**Note** Generally the built in meters are not all that accurate, however they will get you close if that's all you have.

First of all locate the switches you will need for this test.
1) The S/RF, SWR, Cal switch (A three position switch either a slide or a rotary)
2) The variable "SWR Cal" knob
Then familiarize yourself with the meter and scale.

Picture of meter from a Cobra 29

For this procedure you will only be interested in this scale

Tune your radio to Ch 1
Place S/RF, SWR, CAL switch to the "CAL" position
Key the mic on the radio and hold it keyed until noted
Slowly adjust the Variable "SWR Cal" knob until the needle is on the "CAL" mark on the meter
Now place the S/RF, SWR, CAL switch to the "SWR" position
Note the location of the needle (It helps to jot it down on a piece of paper, you may need to do this test a few times more)
Un-key the mic
Tune the radio to Ch 40
Repeat steps 2 thru 7

Wasn't that easy? You have just checked your SWR.

Ideally you should see a reading of 1.5 or less which would be here
GOOD

A reading of 2 or less is considered "Safe", (As long as you are not running a "High Power" radio or an External amplifier) which would be here
SAFE

If your readings are higher than 2, your antenna system needs some attention and you should limit your talking until you get the SWR down
BAD

Tech Support Top

How to check SWR with an External SWR meter

Start off by hooking up the SWR meter to your radio using a short coax jumper. The meter usually has a marking on the front or back of the meter to tell which connector goes to where. The "XMTR" or "Radio" side hooks to the CB with the jumper. The side marked "ANT" goes to the coax lead that connects to the antenna.

**Note** The length of the jumper cable between the radio and the meter really doesn't matter to much if you disconnect the meter when your done. When leaving the meter hooked up at all times, a 3' jumper is recommended.

When using a multi function meter, be sure the mode selector is set to SWR. Then locate the switches you will need for this test.
1) The Fwd/Ref or Cal/SWR switch.
2) The variable "SWR Cal" knob
Then familiarize yourself with the meter and scale.

Picture of a typical SWR meter.

For this procedure you will only be interested in this scale

Tune your radio to Ch 1.
Place Fwd/Ref or Cal/SWR switch to the "Fwd" or "CAL" position.
Key the mic on the radio and hold it keyed until noted.
Slowly adjust the Variable "SWR Cal" knob until the needle is on the "Set" or "CAL" mark on the meter towards the end of the scale.
Now place the Fwd/Ref or Cal/SWR switch to the "Ref" or "SWR" position
Note the location of the needle (It helps to jot it down on a piece of paper, you may need to do this test a few times more)
Un-key the mic
Tune the radio to Ch 40
Repeat steps 2 thru 7

Wasn't that easy? You have just checked your SWR.

Ideally you should see a reading of 1.5 or less which would be here
GOOD

A reading of 2 or less is considered "Safe", (As long as you are not running a "High Power" radio or an External amplifier) which would be here
SAFE