If your CB radio or audio equipment is experiencing noise from electrical interference (such as from your engine) the Metra AWNSFL Noise Filter is a compact solution. This will be installed in between your radio and the power source. The single red connects radio, the black is ground, and the red ( next to the black) connects to vehicle power.
Measuring a minuscule 1-3/4"X1-1/4"X1" the Metra is a 15 AMP inline noise suppressor compatible with receivers, equalizers, and amplifiers.
To reduce noise/interference on the antenna side, check out the NR400, which also amplifies the incoming signal.