This variable frequency (VFO) oscillator was found in a Japanese publication of 1962. Coil details (in Japanese, but can be deduced) are next to the diagram covering the 3.5 MHz band.
This interface was found in a Modern Electronics magazine from 1990. Although the circuit is...
This circuit, found in a 1980 publication, limits the amplitude of the output signal to a value...
The circuit is from old documentation from the 70s, but the components are still common, as the...