I am googling more tools to design the tunnel diode oscillator.  I have little idea what inductors and resistance to use to oscillate the tunnel diode.  I am reading an I2C impedance converter datasheet to get some idea: 
https://tunneldiode.blogspot.com/2020/12/ad5933-1-msps-12-bit-impedance-converter.html.  I am thinking that the tunnel diode with external inductance is sort of RL impedance.  Sot this converter chip might be useful in the oscillator design or measurement. I dont quite understand the DFT operation.  So experimenting with the real DSP chip might help understanding better.