Findings from a couple hours at the lab bench with a CIM and a Jaguar

[zbrozek]

Well, not at the same time, but it's the same method. Basically I find a high-enough frequency where the voltage across at the output of the meter (post-50R source resistor) doesn't change when I attach the motor.

Then I lower the frequency until the voltage is exactly half that. At that point the voltage across the resistor and the voltage across the motor are the same, but I can't measure the voltage across the resistor directly. I have to trust that my instrument is consistent between the two measurements. It's probably a good assumption.