LM3900 Antilog Generator Redux

I've been developing a single-supply antilog generator with the LM3900 and dual 2N5087 PNP transistors for some time.  An original 2020 circuit had some complications, in terms of polarity and range of input control voltage. A later implementation was improved, but it seemed rather complex, though functional: I did not not like the number of trimmers needed to get things to work. A simpler design emerged later, and it was the start of a kind of mystery: why the design would sometimes support forward antilog, and sometimes reverse antilog.

The general circuit design has proven to have relatively excellent tempco properties, due the combination of external PNP transistors and the NPN tranistors within the LM3900. Recently, I had some failures in getting greater mastery over the circuit: creating specific calibration and signal levels. So, to get to the original essence of the circuit, I revisited one of the earlier versions from 2021. I rebuilt from the above engineering notebook page. 

 

Scope fotos follow.