How to Cure CB Radio Feedback

The Snake Eats Its Tail

• Radio microphones include a setting called "gain." This feature, often included as a variable-setting dial, adjusts the acoustic sensitivity of the microphone. If the gain is set too high, the mic hears its own electronic hums. These hums are transmitted through the speaker, which are picked up by the mic, transmitted through the speaker, and then picked up by the mic -- this runaway feedback loop resembles a snake eating its own tail: the more it eats, the more intense it gets.

  As long as the mic is keyed, the high-pitched whine grows in intensity, so reduce the gain until the feedback loop subsides.

Squelch It, Mister!

• CB transceivers include a function called "squelch" that adjusts the sensitivity of the receiver's incoming signal and suppresses the speaker if a signal of specific power isn't received. Clear, local signals require low squelch, because the power of the signal is strong. Faint signals require higher squelch. If a signal comes back very strong -- strong enough for acoustic distortion -- reduce the squelch.

Muffle the Hum

• CB transceivers mounted in vehicles usually receive their power from a direct connection into the vehicle's power system. Unshielded cables, or cables on a broken circuit, may demonstrate electromagnetic hum in some circumstances. If the speaker exhibits a hum that varies in intensity with the vehicle's operation -- e.g., if acceleration changes the hum's pitch -- look to problems with the power cabling between the radio and vehicle battery. The culprit could be an unshielded cable or something like a corroded or damaged wire or connection somewhere on the circuit between the radio and the battery.

Turn That Dial

• One of the benefits of CB radio is the simplicity of channel switches. A CB channel is just a number on a dial; this number, however, represents a discrete radio frequency. Unlike ham operators, who can tune to any frequency on the dial, a CB operator flips among programmed channels that are spaced far enough apart so that signal on one channel doesn't bleed onto another. However, some operators can dial into CB frequencies directly using special gear, while other operators use higher power settings than necessary. This mix of inappropriate use can render some CB channels temporarily distorted, with ghosted or echoed discussion or too much snow. Flipping to a different working channel -- especially one several channels away -- usually resolves the problem.