This circuit uses currently uncommon components, including the 10.7 MHz (FI) filter. This circuit was found in Motorola's 1990 Linear Databook.
The diagram shows a tone control with the LM381 IC. The circuit is from a Radio Electronics from...
Very simple, this radio control circuit for short distances was found in an Electronic Design from...
From an article in Radio Electronics magazine, May 1989, this circuit requires a dual power...