Radio receiver tuning circuit changeover switch - allows reference frequency to follow oscillator frequency during tuning

摘要

The tuning circuit, for a radio receiver, has its reference frequency changed in steps by count pulses. The control stage contains a changeover stage with a changeover switch whose middle contact is connected to the output of a comparator. During tuning the changeover switch is such that the frequency generating stage that produces the reference frequency receives correction pulses from the comparator -thereby allowing the reference to follow the multiplied output of the oscillator. The changeover switch changes over at the end of tuning.