We found this circuit in a 90s Radio Electronics. The integrated circuit used is uncommon today. The table indicates the components for different operating ranges.
The circuit shown is a documentation on 80's tunnel diodes. The frequency depends on the delay line...
This circuit generates excellent sinusoidal signals and has the frequency adjusted by VR1 which is...
This circuit was adapted from an Italian publication that no longer exists. This is “Onda Quadra”...