Tuning a CB antenna in a proper manner is very easy and requires you to follow the instruction. First, you need to install your CB Radio and Antenna as prescribed and ground it well. Now before putting your CB system to work, collect the stuff for the tuning process which includes a good SWR meter and a jumper cable of adequate length. You can check out the steps to make SWR Tunning Incredibly Fast.
- Take your car to open ground or a field where there is plenty of open space around and no trees or tall buildings can be seen nearby.
- Make everyone sit inside the car and keep the doors and windows of the vehicle closed for saving the SWR readings from fluctuations.
- Now you need to put the SWR meter in place. Connect it in a way that the SWR meter is in the middle of the CB radio and antenna.
- Connect the antenna to the SWR meter through the point named ‘ANT’ and connect the CB radio to the meter through the ‘XMIT’ connector.
- Now adjust the microphone in a way that its distance from the SWR meter remains unchanged throughout the measurement.
- Now start the tuning process by adjusting the SWR meter to ‘FWD’ keying the mike and starting with channel one of the band.
- Then turn the adjusting knob of the meter to set the needle on the scale.
- Switch of the SWR meter would be fixed to ‘REF’ while keeping all the other settings the same as before At this point, note down the reading from the scale of the meter and release the mike’s key.
- Repeat all the steps for channel 40 and take the reading.
How To Tune Your CB Antenna
Cber’s & Trucker’s
You should aim to achieve a ratio of 1:5:1 or below across all channels and there should be a minimum difference between the two readings taken above. What SWR meter gives you also depends on your antenna’s length. Yes, depending on your ANTENNA LENGTH.
So you first need to adjust it to the required height. There are two standards to consider here:
- If SWR reading from channel 40 is greater than that recorded on channel 1, the antenna is longer than required.
- If SWR reading from channel 1 is greater than that recorded on channel 40, the antenna is shorter than required.
- If SWR reading from channel 40 is more significant than that recorded on channel 1, the antenna is more extended than required.
- If SWR reading from channel 1 is higher than that recorded on channel 40, the antenna is shorter than required.
If your antenna is too long, then its length has to be shortened through the tunable tip or by trimming it to the required length. The method which suits your CB antenna can be checked from your instructions manual, BUT you have to take new readings for whatever length you achieve for your antenna. If your antenna is too short, then you need to bring it to the required length. You can do it by adding spring between the whip and the mount, or you can try a new length into the shaft.
In case you have mounted dual antennas on your vehicle, then they both need to be tuned by adjusting them through the exactly similar settings. Their length should be the same throughout this process.
If you want to change the antenna length:
Then bring a similar change in the length of both the antennas. Rest of the SWR process should be followed in the same way for both the antennas to get the required readings.
Reading on the SWR meter is a very critical indicator of the transmission capacity of an antenna. A reading below 2.0 is a good sign that your radio is on the right track and you can operate it safely, but the quality of the transmission might not be that satisfactory.
If you get the reading above 3.0, then you should recheck the settings right away as this reading would make your CB system inoperable.
Some common factors cause the SWR meter to show high readings, and they are as follows:
- An inappropriate ground plane is one of the major causes of high SWR readings. A sound ground plane with a full metal surface should be selected.
- The ground straps should be run through as many parts of the vehicle’s chassis as possible. The system should be grounded well with the plane so that readings can be normalized.
- Improper installation and mounting of the antenna is another factor causing the problem. It is always advised to mount the antenna as prescribed in the manual and ground each and every part of the CB system properly to avoid any loopholes.
- Use a voltage meter to determine the points of the vehicle that might hinder the grounding of your system and then try to skip those points out of your system’s path
- Damaged coaxial cable is a big reason behind high SWR readings.
- A coax can get twisted, shorted or pinched while routing through the vehicle. It might come damaged when buying from the market. Hence it is essential to check your coax cable thoroughly before purchasing. Prefer to use a 50-ohm coax for single antennas and a 75-ohm coax for dual antennas.
POOR CB ANTENNA MOUNTING LOCATIONS
If you have achieved a reading on the SWR that is somewhere between 2.0 and 3.0, then your system is not tuned correctly and needs to be rechecked for its settings.
Another major factor that can lead to such high SWR readings is the poor location for mounting your CB antenna. Your mounting location is a poor one if it has the following characteristics:
- I am keeping the antenna below the roofline.
- I was keeping it blocked or covered most of the times.
- Letting the antenna exposed to too much metal in the surroundings.
If your mounting location has these three characteristics then change it right away. What you are THINKING… Just change it. Yes, change it, right away.
No matter which location you choose for your antenna mount, you should test it first through a dummy tuning process to avoid any glitches after the permanent installation. This temporary tune would help you identify the best possible location for the antenna installation.
Why SWR Meter Readings Interpreting
As we have discussed before, the tuning process needs to be performed very carefully so that the SWR readings are within the tolerable range and you can operate your antenna without any risks of getting it damaged.
It is very important to understand what each of the SWR readings actually means and how they affect the CB system’s performance.
SWR 1.0 – 1.5: This range is the ideal one. It has those values that would identify your system as a healthy and safe CB system. You can still achieve 1.0, which is the ideal reading, by tuning your antenna even more or shifting it to a more suitable location on the vehicle.
SWR 1.5 – 1.9: This range is generally the one that has the most commonly obtained SWR readings for all types of vehicles. In normal practice, we can’t obtain the ideal SWR readings so we usually fall in this category that also assures us of acceptable performance levels.
If you still want to bring your SWR reading down, then it is very important to get hold of the best CB antenna possible and mount it on the roof of your vehicle most preferably.
SWR 2.0 – 2.4: This range is an average one but still not very harmful for the CB Systems to operate in this range. Just change your antenna or mounting location if you want to lower these readings to more suitable and safer ones.
SWR 2.5 – 2.9: This range marks the start of the red zone where you cannot operate your CB system safely as these high SWR readings would damage your system one way or the other. Try your best to bring these readings down for an optimal CB experience.
SWR 3.0+: This range is the most unacceptable and dangerous one to operate your radio in. performance of your system would be deteriorated and you would need to ask for serious repairs if you continue to transmit in this range.
All the values in this range show severe issues with the mounting location. If your mounting location is anyone in the described above, haven’t grounded all the components of your CB system properly or your antenna, coax cable or SWR meter might be of poor quality, then your equipment needs to be replaced with the best quality equipment in the market. Because after following these steps got best SWR.