Text: AFC is used in many FM tuners to lock in a station to keep it from drifting out of tune. Since AFC tends to "pull" the tuning to the stronger of two adjacent stations, an AFC-defeat(on-off) control is necessary to permit tuning in weak stations. Some tuners dispense with AFC altogether, relying on a circuit design that is inherently free of drift problems to hold a station steady on the dial. The absence of AFC in a quality FM tuner is therefore not necessarily a drawback.

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Source: 103