Quote Originally Posted by savnik View Post
CA3089 is a monolithic integrated circuit that provides all the functions of a comprehensive FM-IF system, which include a three-stage FM-IF amplifier/limiter ,a doubly-balanced quadrature FM detector.
AND a level detector output at pin 13 ....

AND it works down to audio frequencies too ...

AND NE604 an CA3089 show same functionnal blocks ( of interest here ...) inside

Alain