We found this circuit in a magazine 73 from the 90's. It is a circuit indicated for radio-amateur transmitters with the frequencies determined by the sets of coils.
The circuit shown is from the Texas Instruments optoelectronics manual, applying to low power...
This circuit was found in a 1968 General Electric documentation. It has an input impedance of 2 M ohms...
This filter that rejects a frequency range determined by the double-T was found in the August 1993...