CB Radio Wattage Restrictions

Amplitude Modulation is the most common form of CB radio transmission. AM transmissions on the CB band are limited to 4 watts carrier output power, as measured at the antenna connector on the radio. While you can use a lower power setting, the 4-watt limit is imposed by the Federal Communications Commission.

Single-sideband, or SSB, transmissions, while lower in audio quality and less popular than AM, allow you to communicate over longer distances due to its greater efficiency and higher permissible power output. SSB output on CB is limited by the FCC to 12 watts peak envelope power as measured at the antenna connector on the radio.

Due to these power limits, it is illegal to use an external amplifier to boost the output of your CB radio beyond the legal limit. It is also illegal to modify the radio itself to exceed these power limits, nor is it permissible to use a ham radio -- or any other radio -- that's capable of exceeding these power limits, meaning a radio that is not certified by the FCC. Violating FCC power output limitations can result in fines, confiscation of equipment and possible imprisonment.

While boosting output power is against regulations, you can use antennas to improve signal strength and reception. Raising your antenna as high as practical will improve reception, and while the FCC places restrictions on antenna height, they are not as strict as power limits. The highest point of the antenna cannot be more than 20 feet above the structure on which it is mounted, or higher than 60 total feet above ground. Near an airport, the highest point of the antenna must not exceed 1 m above the airport elevation for every 100 m of distance from the nearest point of the nearest airport runway.

Using a directional antenna -- commonly known as a beam or a Yagi antenna -- can also offer large improvements in reception and outgoing signal strength when it is pointed in the direction of the station you wish to contact, upwards of 8dBi over a vertical antenna. Keep in mind that this adds cost and complexity, as you need to rotate the antenna so that it points in the correct direction.