When we are talking about how to calibrate a CB radio on this page, we aren’t talking about tuning the actual radio to the correct frequency. Instead, we are talking about positioning your aerial in a way that guarantees the best possible signal. To do this, you are going to need to get your hands on an SWR meter.
Introducing the SWR Meter
If you own a CB radio set-up, then you are going to need to get your hands on an SWR meter. There is no way around this. It is the only way in which you are going to be able to get absolutely perfect audio on the radio (both incoming and outgoing).
So, what is an SWR meter? Well, without getting too scientific, these are the core concepts you need to know:
It measures something known as standing wave ratio (hence the name SWR). The meter measures the degree of mismatch of a signal between the antenna and the transceiver
It is a little bit more complicated than that, but we are sure you get the gist. The whole aim is to ensure that the amount of mismatch between the two is as close to zero as possible. You will probably never get it dead on zero, but you can get pretty close following this guide.
Plug Your SWR Meter Into Your Set-Up
The SWR meter will need to plug into the line that connects the antenna to the transceiver. You can leave it in place when you have calibrated your CB radio, but we tend to avoid doing that. Leaving the SWR meter plugged in could add a small amount of interference to the line, and you will probably want to keep that to the absolute minimum.
Before you head out and buy an SWR meter to calibrate your CB radio, you may want to check whether your radio has one built into it or not. If you have purchased one of the ‘bigger’ bits of kit, you may find that there is an SWR meter on it already. Some of the ones we have reviewed on this website certainly have one built into it.
It is important that you read the instruction manual for your SWR meter. We are going to be telling you to do various things, and you need to be able to find that setting on the SWR meter that you have purchased.
Find a Wide-Open Location
Despite what some people may tell you, it is nigh on impossible to calibrate a CB radio if there is interference in the immediate area. Find an area that gives you a substantial amount of space around your vehicle. An empty parking lot would be fine here. You will also want to ensure that the only person anywhere close to your vehicle is you.
- Tune your radio to channel 1.
- If there is a separate button to press on your SWR meter to activate SWR mode, then you will need to press it now.
- Once everything is set-up, you can pick up your microphone. Press the button as if you were going to transmit, but do not make a sound. Don’t speak at all. It will ruin the reading.
- Take a look at the SWR meter and note down the number that appears. This is your first reading.
- Tune your radio to channel 40
- Repeat the same process as you did for channel 1.
- Make sure you note down the reading that the SWR meter gives you. There is a chance that it is going to be a bit different to the one given to you on channel 1, particularly if you have not tuned your antenna before.
Analyzing Your Readings
As mentioned previously; in an ideal world, both of the readings would be as close to zero as possible. It is unlikely that they are, particularly if you have not tuned your antenna before.
If both of the readings are under 2, you could potentially adjust your antenna a little bit, but it may be more hassle than it is worth. The audio quality is not going to be pristine at a reading like this, but it is going to be passable. The only reason to calibrate your radio’s antenna if both numbers are under 2 is if you are looking for crystal clear audio at all times.
The main thing you will be looking for in your readings will be whether the number for channel 1 or 40 is higher. This will dictate how you tune your antenna.
Tuning Your Antenna
If you have a higher SWR number on Channel 1, then you will need to lengthen your antenna. Most antennas will have a little bit of leeway in them, which means you can lengthen them a small amount. If you can’t, then you may need to purchase a new antenna.
If the SWR number on Channel 40 is higher, then you will want to shorten your antenna.
You may also find success in repositioning the antenna on your vehicle. For example; most people find that it is easier to get good SWR readings when the antenna is located on the roof of their vehicle.
How Often Should You Use Your SWR Meter?
Honestly, it isn’t something that you are going to be using all that much.
Many people will check their antenna tuning every couple of months. If you see a decline in audio quality, then you may want to do a quick check with the SWR meter. It could mean that the antenna has been bashed around a little bit and needs to be repositioned.
If you are heading into a completely new area e.g. you have changed states, then you may also want to look into retuning your antenna. Again, it isn’t really necessary, but it is always worth ensuring that your antenna is in the best possible position.
Remember; this is a process that only takes a couple of minutes at the most. That is presuming you do not need to make any adjustments to your antenna. It is always worth checking every now and then. It will ensure that you have the best audio quality at all times.