The amount of noise reduction, from none to maximum, can be selected with the 3-way switch.
The NR400 installs in-line between your CB radio's output and the antenna.
The NR400 is also great to user with amateur radio frequencies above and below the 27MHz band.
If you are using the NR400 with your amateur radio and a linear amplifier,
connect the line from your radio to the NR400 first, then connect the NR400 to the linear amplifier,
then connect the linear amplifier to your antenna.
