How to Calibrate a CB Radio? – 5 Easy Steps


Written by

Rafeal Hart


Fact-checked by

Norris Howe

how to calibrate a CB radio

It’s a must to learn how to calibrate a CB radio as it’s a skill that every enthusiast should have. After all, a radio is not always in its best shape, so knowing how to tune it goes a long way.

To do so, connect a standing wave ratio (SWR) meter to the radio, conduct readings on channels one and 40 without saying anything in the microphone, and tune the antenna if needed. Some citizens’ band radios have a built-in SWR meter, which makes calibration easier for users.

What to Prepare to Calibrate a CB Radio


The only thing you need to calibrate a CB radio – aside from the radio, of course – is the SWR meter. Buy one if you must, as it will help you, especially when you need to peak and tune a CB radio.

However, if your radio has a built-in SWR meter, you’ll have a smooth time tinkering with it.

Step-by-step Guide for CBs Without Built-in Swr Meters

Before anything else, if your CB radio is in a car, it must be parked in an area without obstruction. Ideally, there should be no buildings, trees, or hills 12 to 15 meters from the antenna.

It is the best-case scenario for an optimum SWR reading, though it’s not always possible, especially for amateur radio enthusiasts in a rural area. Be that as it may, you can still calibrate your CB with an SWR meter. 75.

Step 1: Link the SWR meter and the unit


Setting the SWR means connecting it to the antenna and radio – serving as a link between the two during calibration. First, plug the antenna cable into the SWR meter.

Afterward, the cable from the meter will be connected to the CB radio. So two cables link to the SWR meter.

Now, assuming you have this “bright” idea of not unplugging the SWR meter after calibration so you don’t need to connect/disconnect it every tuning, think again. A permanently-set SWR on a CB radio might cause interference. As such, plug in the meter only during calibration, and unlink it after use.

Step 2: Take the first reading


First, lower the transmitter’s output power before taking the first reading in channel one. Afterward, click the forward (FWD) switch before rotating the knob to calibration (CAL).

In this mode, forward power travels from the transmitter to the antenna. During the transmission, adjust the knob as needed, but ensure that the SWR’s CAL on the CB radio is 100 percent.

Afterward, set the switch to the reflected (REF) mode. This position specifies the power not absorbed by the antenna as it returns to the transmitter. End the transmission and record the result for later reading.

You must press the microphone’s push-to-talk (PTT) button while calibrating channel one but don’t say anything over it.

Step 3: Take the second reading


Follow the same steps above but do it on channel 40. Normally, it has a different reading from that in channel one.

Step 4: Check if there’s a good SWR reading


An SWR of 1.0 is ideal but unlikely. In such a case, the antenna absorbs all the forward power. Aim for a reading in the 1.2 -1.3 range. It’s important to note that 1.8 is the safest limit.

A CB radio’s SWR is too high if it reaches 2.0 while hitting over 2.5 might damage a radio.

Step 5: Tune the antenna, if needed


Adjusting the CB antenna is required depending on the SWR reading.

  • If the SWR in channel one is higher than in channel 40, the antenna needs height adjustment.
  • On the other hand, if channel 40’s SWR is higher than in channel one, you need to shorten the antenna.
  • In the case of setting SWR on dual antennas, if the reading is less than 2.0, the radio is safe to operate, but don’t expect optimum transmission.
  • On the other hand, if the meter registers over 3.0, you need further calibration and antenna tuning to fix the high SWR on the CB.

Tune a CB Radio With a Built-in SWR Meter


  1. After turning on the CB radio, turn the knob on channel one or any other channel not in use; meaning, there is no current transmission or interference from other radio users.
  2. Afterward, put the SWR toggle from signal strength/radio frequency (S/RF) to CAL, then grab the mic and press the PTT button but don’t talk over it.
  3. Then turn the SWR knob to CAL until the hand in the meter reaches the calibration marker. Put the toggle in SWR and record the readings.
  4. Lastly, return the toggle to S/RF. Repeat it on channel 40 or any other channel that’s not busy. With the recommended readings mentioned above, gauge if you need to tune the antenna.

Tune a CB Antenna Without an SWR Meter


If you’re calibrating a CB antenna but don’t have an SWR meter, you’ll need another unit, say an Uniden CB radio, which needs to be set up in the vehicle far from the other but must be in the same frequency.

When a connection is established from the antenna to both radios, grab the microphone of the unit you’re tuning, then talk over it. The radio and the antenna are in tune when the other CB picks up your transmission.

When the transmission is clear, then consider the CB radio tuned. Otherwise, adjust the antenna until the line becomes clear. It’s best to have a companion during this test, with one of you listening to the spare CB.

Tips for Accurate CB Radio Calibration

As mentioned, the ideal way to register optimum SWR readings is when you’re in a place without obstructions – buildings, trees, towers, hills, and such. However, even in such a case, some issues in your unit might prop up, which you can easily troubleshoot.

Common Mistakes to Avoid


  • Cable length is not enough

When the SWR meter (not built-in into the radio) reading is always on the red, the coaxial cable might be short. Ideally, it should be 18 feet. To avoid such an issue, make sure you’re using the right cable and connectors, plus without any damage from crimping, bending, and such.

  • Poor electrical ground

Another reason for the high SWR rating is poor electrical ground, which you can resolve by assuring metal-to-metal contact between the antenna mount and the chassis. You can use a multimeter to check vehicle ground. If good ground is absent, you can use a grounding strap or scraping paint off where the mount contacts the chassis (though this is not always recommended).

  • Poor antenna mount

As with poor ground, an improperly installed mounting stud can also result in high SWR readings, so make sure it has enough metal and is sturdy. Furthermore, the best antenna location is in the center of your car’s roof.

Frequently Asked Questions


What is an SWR meter? How does it work?

An SWR meter measures the strength of a radio’s transmit signal as it travels through the antenna and to the atmosphere, helping users gauge the mismatch between the two, if any.

The meter troubleshoots problems in the radio/antenna. Treat it as a diagnostic device so you can use the antenna at its maximum potential, and adjust a CB radio as needed.

Why is SWR calibration important for CB radios?

Regularly tuning a CB radio will help maintain your unit’s health. Calibration ensures optimum performance. After all, you don’t want poor reception when you need it the most.

How often should I calibrate my CB radio with an SWR meter?

Whether you’re using a RoadKing CB radio or any other brand, it’s important to calibrate it every few months for routine checkups. You also need to recalibrate if the unit’s performance deteriorates, so possible antenna issues won’t surprise you.

Furthermore, when you move to a new community, recalibration is always recommended to ensure optimum performance.

What are the consequences of neglecting CB radio calibration?

Tuning a Cobra CB radio or any other brand means you’re ensuring that the unit is still in good condition, the antenna is not underperforming, and the transmission is beyond commendable.

When you miss the chance to regularly calibrate a Cobra CB radio or any other brand, you’re prone to poor transmission, and you won’t have the chance to detect possible issues that might affect the radio and the antenna.


Now that you know how to calibrate a CB radio, keep in mind that it’s not a one-time thing. Amateur radios depend on frequencies, the environment, and many other things, so transmission is not always clear. As such, regular tuning will keep you away from headaches due to reception issues.

You can calibrate and tune radios/antennas with or without an SWR meter, so you have no reason to neglect this duty of every enthusiast.

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