CB Radio Amplifiers are one of the easiest ways to greatly extend the range of your transmitter setup, easy to install and use these power amplifiers will work perfectly if you follow a few simple guidelines.
If your new to CB this post will get you started and go through some of the other things like interference and choice of antenna. We’ll also look at a few simple RF linear amplifiers that economical to run and have a low profile design.
A basic CB amplifier will take the 4 watts output from your CB and turn it into 50, 100 or 500 watts of RF power, generally these types of amplifiers give you no control over the amount of output and the only way to reduce it is to put less RF power into the amplifier.
By switching your CB to low power you can usually turn down the power output from the amplifier by a factor of ten.
Some amplifiers will allow you to vary the power by using a control dial but you will pay more for this useful feature.
Before you Start Using a CB RF Amplifier
Make sure your antenna is in good working order before adding an amplifier to your CB setup. Ensure you have good quality antenna coax installed because cheaper coax that will work fine when you are pushing 4 Watts of power through it may not be able to handle 100 Watts.
All branded coax will have its model number printed on the outside of the protective cover at regular intervals, allowing you to see exactly what your using. If your unsure about the particular rating of the coax you already have installed a quick online search with the model number should tell if its suitable for the power output you have planned.
Coax with no markings can mean its of the worst quality and I’d rather change the whole thing before using a linear and take away that unknown factor.
Check the antennas S.W.R (standing wave radio) to make sure there is as little mismatch as possible between CB and antenna by using a S.W.R meter. Putting 100 Watts into a badly matched antenna will cause you a whole load of serious problems and could even shorten or end the life of your shiny new amplifier.
Go over antenna connections and make sure they are clean and in good condition, if your going to invest the time and money installing an amplifier having a healthy antenna system is going to let you get the most out of it.
Increased CB Power and the Law
Many countries will only allow a certain power output from CB radios with the common figure being 4 Watts, by adding an amplifier to your CB you could be breaking the law and face a heavy fine and having your radio equipment confiscated. Sometimes the confiscation is not limited to the piece of equipment that you are using to break the law but can include any transmitting equipment you own.
Please check your local laws before considering installing an amplifier.
Any powerful transmitted has the potential to interfere with any number of other domestic services with television and radio being the most likely, following the guidelines above and making sure your antenna is working properly with always cut back on the amount of interference your CB will cause to others.
If you are sure that everything is working OK and you still have complaints of interference the best option is to only use the increased power selectively. By only using full power when the services you are causing disruption to are not running or being widely used like the early hours of the morning you can keep interference to a minimum.
Unfortunately from our own experience because you have a big honking antenna on the side of you house you will most likely get blamed for every bit of random interference that your neighbors suffer.
Even when only having antennas mounted outside for receiver purposes only we have had regular complaints, our best advice is be polite and try to get to the bottom of the problem. If you can prove its not you or even better fix your neighbors interference problem you will have someone on your side to defend any future complaints.
Powering your Amplifier
Powering your CB and an amplifier off the same power supply will work but don’t expect to get both working to full capacity from a basic 13.8 volt power supply. The current output from the power supply should reflect the RF output of the amplifier and if you can power the amplifier from a separate supply than the CB then all the better.
Your linear can also run nicely from a 12 volt car battery indoors but there’s still the issue of making sure the battery is topped up so you get the most from your CB setup.
Unlike a regulated power supply a battery will lose its maximum current/voltage output quickly when used at the levels a big RF amplifier requires and reducing the overall effectiveness of the linear.
Using your Amplifier Safely
At first glance it doesn’t seem possible to get any injury from using a RF amplifier but there is a real danger of you or someone else suffering from what is called RF burn.
The increased power that you are outputting from your antenna system is still a form of electrical energy and has the ability to give a substantial shock to anybody who comes in contact with the antenna while you are transmitting, with this is mind consider where you place your antenna so that no one can accidental touch it.
At very high frequencies just being near enough to a radiating antenna or in the path of a directional radio signal alone can cause RF burn with out ever having to actually touch any part of the antenna system.
For most of us this wont be a problem as you will want to mount the CB antenna as high as possible and away from obstructions to make the transmitted radio signals as effective as possible.