This amplifier with the EL84 tube is a European commercial type from Corpim mounted on a printed circuit board. The diagram appeared in a September 1958 Radio Electronics magazine.
The configuration shown is suggested by National Semiconductor in its 1994 Linear Applications Handbook....
This simple receiver, which requires a good antenna and grounding, was found in an Argentine...
This circuit was found in an Electronic Design from the 90s. Operational amplifiers admit modern...