The purpose of this circuit is to check the linearity of SSB amplifiers. The circuit was found in an old documentation for hams. The diode is a general purpose detector type.
This configuration can be found in other articles on this site. This is from European...
Using an LDR as a sensor, this circuit is from the Radio Electronics magazine of December 1984. The...
This circuit was found in the August 1994 issue of Electronics Now magazine. The 4046 is uncommon...