In the 1970s, receivers began to be designed using frequency synthesizer circuits, which synthesized the receiver's input frequency from a crystal oscillator using the vibrations of a precision quartz crystal, which had a stable enough frequency that AFC was not needed.
Receivers began to be designed using frequency synthesizer circuits. This was in the 1970s. Frequency synthesizer circuits synthesized the receiver's input frequency from a crystal oscillator. This crystal oscillator was using the vibrations of a precision quartz crystal. AFC was not needed. A precision quartz crystal had a stable enough frequency this.