The operational 714 (not the 741) is an old Raytheon type that is no longer common today. The circuit can be implemented with modern operational. The power supply must be symmetrical.
When the voltage exceeds the value given by the zener, this circuit from a 1990 documentation...
This circuit for the 11-meter band, operating at 29.255 MHz was found in a Radio Electronics dated...
Found in a Popular Electronics from the 9s, this circuit has output for RS-232 interfaces and current...