This circuit is from an old documentation, making use of an operational of the time. The circuit can be adapted to use modern components. The power supply must be symmetrical.
This is the typical circuit of an FET amplifier stage in the common source configuration. The circuit is...
Pressing and releasing S, the capacitor C1 charges and discharge slowly through the oscillator...
For the 7 to 10 MHz band L1 is formed by 3 turns of 22 to 28 AWG wire in a ferrite core 15 to 20...