ANTENNA TUNING

Steps for Proper CB Antenna Tuning

CB antenna tuning holds a very important place in the installation process of a CB system. It determines how well the CB antenna will perform in coordination with the CB radio once it is properly tuned. You may require your antenna to work as effectively as it can be to optimize your radio’s transmission and reception power. This guide describes the complete process for tuning a CB antenna effectively to get the best results.

1. Tune Antenna in Open Area

Start by selecting the space where your tuning will be conducted. The most ideal place is any open area where there are no big buildings, large trees or other kinds of hustle and bustle. Ensure that windows and doors are closed down to guarantee an exact reading through.

2. Place a Good SWR Meter & Antenna in line with your System

(see our section on SWR)

(SWR Meters available with us at www.teamgeomax.com or call 98184 17676

Procure a SWR meter. Some radio models such as JFK II have a an in-built SWR meter that works great. Before Tuning your CB Antenna. You must have knowledge about SWR Meter. Some major factors that can affect the SWR value drastically are;

Inappropriately tuned antenna,

Ineffective length of the antenna,

Grounding not done properly,

Damaged coax cable

Improper soldering of the connector joint

Earthing/grounding while installing the antenna

Bad location on vehicle

Closed area

Interference such as power lines, mobile towers and high voltage installations

The two most important labels that you need to notice on the meter are ‘TX’ and ‘ANT’ found on the two ends of the meter’s front face.The former provides a connection point for the radio while the latter serves the purpose for the CB antenna. On the back side of the meter, two corresponding jacks are also available right behind these labels. Make sure you connect the antenna and radio cable properly into these jacks otherwise your CB antenna tuning will lead to high SWR readings.

Now take the jumper cable that usually accompanies the SWR meter but can also be bought separately. Two separate pieces of jumper cable will be required for connecting CB antenna and CB radio to the SWR meter in their respective jacks.

3. Take Readings on Channel 1 and 40

Start the CB antenna tuning process by taking SWR readings on channels 1 and 40. First tune your radio into Channel 1. Turn the switch on the SWR meter to ‘FWD’ and key the microphone by pressing down the talk button continuously. The needle on the meter will jump up indicating successful keying of the microphone.

Now move the calibration knob to bring the needle to the ‘SET’ position. Now keeping the mic keyed, turn the switch from ‘FWD’ to ‘REF’. Once you do this, the needle will instantly change the position and the point where it stops will give you the first SWR reading on Channel 1. After this, you can unkey the mic. The reading on Channel 40 can be obtained by repeating the same process for that channel.

The readings that you will obtain for these channels will determine what kind of treatment you will give to your antenna during the tuning process.

If the SWR on Channel 40 is greater than that on Channel 1, your antenna is quite long and the tuning will be effective when you will shorten it.

IMPORTANT TO NOTE THAT THE CB ANTENNAS WE SUPPLY ARE PRECUT TO THE RIGHT LENGTH. PLEASE DO NOT CUT THE ANTENNA ROD AS IT WILL AFFECT THE PERFORMANCE AND RENDER THE ANTENNA USELESS

If CB Antenna is Longer

You can reduce its physical length. There are many techniques for reducing an antenna that vary by manufacturer. Check your owner’s handbook regarding precise directions regarding how to limit your antenna. Several antennas might need to be cut to get reduced. Do this within 1/4″ steps and after that get new readings to find out your results.

If the SWR on Channel 1 is greater than that on Channel 40, your antenna is a very short one and the CB antenna tuning will be effective when you will increase its length.

If Antenna is Shorter

You can increase its physical length. Mostly antenna length is just too small are due to an absence of ground plane. In present day antennas, there’s often a way of adding length built in to the antenna. Other options, such as adding a spring, will also works.

Another important aspect that you need to focus on during the CB antenna tuning process is to leave the weather cap on the antenna while taking the SWR readings on different channels. Take it off when adjusting the antenna length. Once you loosen the set screws on the antenna, make small incremental changes in the length of the antenna, whether you are increasing or decreasing it. Take readings again after each adjustment to find its overall effect on the SWR.

5. Goals of CB antenna tuning

There are two main goals that you need to achieve during the CB antenna tuning process and by taking the SWR readings

The final SWR obtained should be below 2.0 across all the CB channels. It ensures that your CB antenna is operating efficiently and safely and your CB radio is free from any possible damages due to SWR fluctuations. Values obtained between 2.0 and 3.0 SWR are dubious. If an SWR of 3.0 or above is obtained during the tuning process, quickly turn the CB radio off as it will destroy your antenna’s performance and will damage your radio too.

SWR values obtained on Channel 1 and Channel 40 should be similar or very close to each other.

What should I do with my SWR meter once the Antenna tuning process has been completed?

Unscrew the jumper cable from the jacks and remove the SWR meter from your CB system. Now make normal connection between your CB radio and antenna by connecting them to each other.