FM PLL using CA 3089

The following circuit should prove particularly interesting to those readers considering building their own FM tuner. The novel feature of the circuit is that the well-known CA 3089 IC is not used as a conven-tional IF am pi ifier /demodulator, but as part of a phase locked loop. The resulting circuit is slightly more expensive and complicated than the `standard` amplifier/de-modulator circuits, however the results obtained are a significant improvement on those of a `classi-cal` CA 3089 IF strip.