The purpose of this circuit is to measure the resistance of an antenna at the resonant frequency. The circuit is from an old American documentation for hams.
We found this circuit in an Electronic Design from the 80's. The generated tone can be changed as well...
In the figure we have an oscillator circuit by Wien Bridge (Wien Bridge Oscillator). The frequency of...
We found this circuit in Intersil documentation from the 1980s. The circuit applies to other...