I decided to measure the two inductors that were confusing me in Colpitts LC oscillator, using the same method I’ve used before to model loudspeakers, that is, applying a known frequency sine wave to the unknown inductor in series with a known resistor, and measuring the RMS voltage across the inductor and across the resistor.
I decided to use the Bitscope Pocket Analyzer’s built-in function generator, rather than the external one I used before, because it is easier to set the frequency precisely, so I did not have to keep switching my Fluke 8060A multimeter between voltage and frequency measurement. For the big inductor, I used a 100Ω resistor (measured at 100.64Ω), while for the AIUR-06-221 inductor I used a 1Ω resistor (measured at 0.98Ω). To prevent overloading the function generator, I added another 100Ω resistance in series with the AIUR inductor+1Ω load, so the voltages measured for the AIUR inductor were pretty small.
My son helped me take some of the measurements, which was pretty boring, in part because it often took the Fluke multimeter 30–60 seconds to stabilize after changing what was being measured.
I computed the magnitude of the impedance of the unknown device as , and fit the function to the resulting impedance values.
These measurements are consistent with the data sheet for the AIUR-06-221 inductor, and consistent with the L/R time constant measurement for the big inductor.
I still don’t understand why the Colpitts oscillator and the phase-shift measurements were indicating a different inductance. Maybe I need to check the capacitor values (I did check the markings on the capacitors, tiny as they were).