Finally, you have a CB radio! Congratulations!
Though I understand it’s natural to feel excited, you need to do certain things before you can enjoy your radio’s optimal performance.
Among them, one of the most important is to know how to set SWR on CB radio.
More than maximizing performance, tuning a CB antenna prevents potential catastrophic damage to the radio.
If your antenna is poorly-tuned, you’ll experience interference and dropped signals.
More so, there can be power reflection back to the transceiver, which can damage the output transistors.
Read on and learn the basics of tuning your radio and setting the right SWR.
Table of Contents
What is SWR on a CB Radio?
Standing Wave Ratio (SWR) measures an antenna’s performance. It tells you whether there’s an impedance mismatch, which affects the overall transmission of the radio.
One of the first things to do upon the installation of a CB radio is to check its SWR. It must fall within a specific range, which I’ll be talking about more later. A poor reading can show an issue with the installation of the antenna or the quality of the antenna itself.
To measure SWR, you’ll need an SWR meter. Some of these devices will come with a backlight for easier reading.
A Step-by-Step Guide to Set SWR on CB Radio
What to Prepare
- SWR meter
- Bolt cutter
Step 1: Pick a Location
The first thing to do is to choose the right location to complete the SWR adjustment. Wherever you put the antenna, make sure its surroundings are free of anything that can block signals and affect your results. 15 feet of free space are ideal.
You must also avoid metal objects that are not the antenna mount. Walls, such as in garages, should also be avoided. They can interfere with the signals, which can make the readings inaccurate.
The best place to calibrate SWR is in a parking lot or open field. This way, you will not have obstructions.
Step 2: Connect the SWR Meter
Once you find a suitable location, it’s now time to link the SWR meter. When you do so, close the windows and doors of your car to ensure better accuracy.
Look for the far end of the radio antenna cable. Next, connect the antenna/radio to the meter through the coax cable and the jumper lead. Use the ANT and XMIT slots for this.
Step 3: Turn the SWR Meter On
After connecting the antenna and SWR meter, it’s time to turn the latter on. Look for the power button and push it. The display will light up after activating.
Nonetheless, take note that some SWR meters will not have a power button or an indicator light. Instead, they’ll automatically turn on after connecting to the antenna.
Step 4: Measure and Set the SWR
Now comes the most important step in this guide. Follow this order of steps on channel 1:
- Switch the meter to FWD or forward power to measure what the antenna receives–you should see this button marking on your device.
- Key the transceiver/microphone. While you are holding the mic, turn the set or adjust knob to position the needle SET or CAL.
- Switch the meter to REF, which will indicate the amount of reflected power on the transmitter.
Afterward, do the same things as above, but this time on Channel 40. Make sure to take note of the readings.
Step 5: Tune the Antenna
Depending on the readings that will show up on the SWR meter, you will need to tune the antenna. Doing so will let you achieve the right SWR setting.
With the SWR higher on 40 compared to Channel 1, the antenna is longer than necessary. Hence, the next thing to do is reduce its length.
To shorten the antenna, start by putting it in a vice, which will secure its position. Use a bolt cutter to shorten it. Adjust the length in ¼-inch increments. Do not cut more than what’s necessary.
Meanwhile, the antenna can also be too short. This is the case when you have an SWR higher on 1 than on 40.
If the antenna is too short, find a way to make it longer. A spring is one of the best tools that can make an antenna longer to potentially improve SWR.
Alternatively, some antennas are designed in a way that you can adjust the length. For instance, you can do this by loosening the screw at the bottom part, raising the antenna, and getting the screw back to tighten the connection.
How Do You Check Your SWR?
You will need an SWR meter for CB radio. It is an inexpensive but handy tool that you will need for CB SWR tuning.
Different types are available, but the principle of operation remains the same. The reading in the meter shows if the antenna load matches the transmitter feeder. Depending on the range that shows in the meter, you can have an idea of your antenna’s performance.
Things to Know About SWR Range
To know if you have a higher or lower SWR on antenna, you must be familiar with its range, which is briefly explained below.
- 1.0 to 1.5
This is the ideal range that you should aim for. The goal is to get it as close to 1 as possible. So, if it’s already at 1.5, a few tweaks might be necessary.
If the range is higher, you might need to tune the antenna or pick a different mounting location.
- 1.0 to 1.9
This range means that the antenna has the potential to improve. Even if the numbers are slightly higher than what’s ideal, the overall performance remains acceptable.
- 2.0 to 2.4
While it can be categorized as a high SWR reading, it isn’t enough to destroy your radio, especially if you’re just a casual user. A common reason for the poor reading is the position of the antenna, so you might see an improvement by changing its location.
- 2.5 to 2.9
Adjustment is necessary if your radio has this range of reading. Unlike the 1.o to 1.9 measurements, performance here is significantly lower.
- 3.0 and Higher
Consider this reading as a red flag. Extended transmission within this range can result in significant equipment repair and replacement. It’s a dangerous situation that can ruin the radio only within a few minutes. Fix high SWR on CB before transmission.
What is Good SWR for a CB Radio?
A good SWR for CB radio is 1.0 or a number as close as possible to such but without going over 1.5. At this range, you can enjoy optimal performance and prevent radio damage.
How Do You Fix a High SWR on a CB Radio?
One of the first things to do is adjust the length of the antenna accordingly. The antenna can be too long. Hence, you need to reduce its length.
Alternatively, you can also change the mounting location of the antenna. Avoid mounting it low on your vehicle or close to its body. It’s best to position it on a flat radiating surface.
Fixing a broken antenna is another potential solution that can help you improve your communication. If the copper wire that wraps the fiberglass pole breaks, expect to get a high SWR.
Lastly, you should also put metal under the antenna. Otherwise, there can be insufficient ground plane, which is another reason for a high reading.
Can You Tune a CB Antenna Without an SWR Meter?
Yes, you can tune CB antenna without SWR meter. Similar to the steps mentioned earlier, you’ll need to find an open location. Next, choose a channel, except for channel 9 or 19.
After this, you can connect two radios (one is your car CB; the other is a correctly tuned transceiver). Press the mic and speak. Talk with your partner while you adjust the antenna and observe how the reception changes.
You can loosen the screw and tweak the height of the antenna. Changing its location could also work.
Being familiar with how to set SWR on CB radio is a handy skill you need to learn. The best way to do so is to use an SWR meter.
Eliminate guesswork and gauge the radio’s performance with the help of this device. It will help you adjust your antenna quickly and safely.
As mentioned above, doing this task is easy. It’s a quick DIY job that anyone can carry out with the right knowledge and tools.
Hi, I am Amaro Frank – the Wind Up Radio’s content editor and writer. Working with Adam is so much fun, as his stories and experiences enrich my knowledge about radio communications and radio accessories. My main tasks in Wind Up Radio are building content and generating great articles on different topics around radio accessories.