Thanks for the response. I tried linear, but couldn't get much out of it, so I went back to Exp as the directions said.
What I did do is change my Tuner App-from Cleartune to TonalEnergy Chromatic Tuner from Sonosaurus LLC, which claims to be responsive to all instrument types from C0 to C8. It includes square, sawtooth, and sine wave forms as instruments it is responsive to. When I tested my first calibration mentioned above with this TonalEnergy, it read what Cleartune reported as a G6 as a G7. So I re-calibrated using the TonalEnergy App. Here are the results
Octave Open Circuit Voltage, V Frequency, Hz Note
1 0.019 195.8 G3
2 1.011 391 G4
3 2.005 782 G5
4 2.999 1565 G6
5 N/A 3138 G7
I could go another octave up, but by then it was a solid F#8. I have since retuned the VCO to C1. and I can get to C5 all within +/-1.5 cent.
While I have no idea if this new app is accurate, it is giving results that I would expect given the input voltages, and I am going with it. The developer has produced a very detailed Users Guide, and has an online forum, so it appears that they have taken alot of time making and supporting this app. Someday, if I find someone with a high accuracy tuner, I will test it out, but in the meantime, I am going to have some fun.