dewster, when I made the statement of my pitch drift being less than one musical note when set at 300 Hz over a room temperature change of 10 degrees F was not an exaggeration. Lev’s Antenna is all I have ever known and my conversation with other designers might be disqualified because we are comparing apples with oranges.
When you have drift over time at a consistent room temperature that is from unwanted internal warming which must be avoided. That is one reason my oscillator section can be separated from the main board if needed.
Lev’s Antenna is a hardened steel 16” spring coil as you know. This could be compensating or countering external room temp induced thermal drift by changing the pitch oscillator loading when the antenna expands or contracts ever so slightly? (Due to lack of formal electronic training I will use the word loading) I am sure the apples use another fundamental term. LOL
Do you see scientific bases for this thinking?
Maybe the antenna has more than one effect on the pitch other than originally recognized.
I need an invitation from a So. California Classical Thereminist that I can set up the Theremin Phoenix so they can validate my theremin voice, response & research.