I checked and as expected, the MFOS VCO has the same problem as the LFO: with an attenuator on the PWM CV, changing the attenuator changes the pulse width even with no CV plugged in. I applied the same fix, replacing the 100k pots with 25k and the 10k mixing resistors with 200k. I found that even with my PW mod in place to increase the PW pot limits, the PW range was smaller than before — not what I was expecting. Well, clearly the whole PW section could do with a complete redesign, but I decided to just declare victory and call it good. Again, if I really need 98% pulse width, I can get it with a suitably large DC control voltage.
(And I did do the calibration.)
Read the rest of the MFOS VCO build series: