CB Radios for Overlander’s CB radios are a necessity for many overlanders and off roaders and a requirement for many organized trail rides. Let’s talk a bit about choosing a CB, an antenna and some tips for installation. Choosing a CB Radio One thing you need to understand is that the transmission power on a CB radio is limited to 4 watts by the FCC. This means that all CB‘s are manufactured to meet this requirement. Choosing a CB isnt about the power, rather what fits in your vehicle and meets your needs. Jeeps and other 4x4s often have limited cab space so size is a consideration. Larger radios can have all the extra bells & whistles which may be nice to have, but most off roaders usually lean toward radios that are simple, durable and small enough to mount out of the way while being able take a beating. An example of one such radio that is popular for off road use is the Uniden Pro 510 XL or 520 XL. This small, simple radio is has basic CB functions and is very resilient to vibration and dust. Specifically for limited space vehicles, is the Cobra 75 WX ST. With all the controls in the microphone, it allows you to mount the radio itself well out of the way such as under the dash or a seat. Another popular unit is the Midland 75-822 handheld. What make this one so nice is that it can be plugged into both your vehicle’s power and external antenna. You can operate with the efficiency of a mobile unit one minute and then replace the battery pack and rubber-duck antenna to use as a handheld while spotting someone through an obstacle. These radios are only mentioned as examples and not as recommendations. CB Antennas Because CB radios are restricted to 4 watts of power, the CB antenna is the most important part of your CB setup. The quality and length of your CB antenna will be the primary factors in determining your CB’s range and performance. There are two common types of CB antennas; fiberglass and wire whip antennas. As well there are two common mounts; permanent and magnetic. Most off-road drivers choose a fiberglass CB antenna on a permanent mount, as they are more suited for trail use. One such antenna is the Firestik FS. It has a tunable tip for matching the CB antenna to your radio (see “tuning” below). At heavy spring is often used between the antenna and the mount to reduce bending stress from tree branch strikes and the like. Another antenna is the Wilson Flex which was created specifically for off road users. As its name implies, this antenna is able to bend 180 degrees without breaking and can also be tuned. Antenna Mounts For many off roaders, choosing a location to mount your CB antenna will be an easy task as many companies make vehicle specific mounts. For the rest of us, there are many universal mounts that make attaching a CB antenna an easy task. With a few tools and a little fabrication skill, you could easily make a mount yourself. When choosing a mounting location, you will need to choose a metal spot on the vehicle that is grounded to the chassis, or can be easily grounded. Having a solid ground is crucial, as the CB antenna uses the chassis of the vehicle to create a radio ground plane for sending and receiving CB signals. If your antenna mount is not properly grounded, your CB will have poor performance. Keep this in mind when mounting to powder coated or bed lined parts. Though the center of the roof is ideal, you also need to consider where you drive and what might come in contact with the antenna such as low hanging branches which could cause damage. Some of the best places to mount a CB antenna are the rear bumper or tire carrier, the rear fender, inside the tail-jamb, or to a vertical or horizontal bar. You want to have at least a portion of your antenna above the roof line, but not so much that it won’t bend clear if it hits something. This will limit your transmitting power in certain directions, but often you only need to reach the vehicles in line with you on the trails. Nothing says you can’t have a second magnetic whip antenna, ready to place on the center of the roof for longer range, paved road use. CB Antenna Tuning The final step in CB installation is tuning your CB antenna. Without getting too involved, CB antennas need to be adjusted to match each specific chassis and mounting location, as the ideal signal length from the CB to the antenna differs for every vehicle. While this process might sound daunting, it is actually quite simple. Using an SWR meter, you will test the CB system and either raise or lower the length of the antenna (using the tunable tip), until the SWR is at its lowest point. Simple follow the step-by-step instructions that come with any SWR meter (or Google search). Basically speaking; if the SWR on channel 40 is higher than that on channel 1, your antenna is too long. Conversely, if the SWR on channel 1 is higher than that on channel 40, your antenna is too short. Ideally, a 1.5:1 ratio or below on the meter makes for an optimal broadcast signal. Please comment to share your CB related tips, experiences or questions below.
Posted on: Fri, 18 Jul 2014 21:08:33 +0000
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