"FWIW here’s my method for measuring inductance."
That looks like a good setup.
On a related note. I have a number of cores that that are not color coded. As long as I can keep track of which is which they work as intended from the supplier (but the specs supplier are rather slim). However, I'd like to characterize these cores to match them up with the actual mixes and frequency performance so I can buy generic toroids. Is there any reasonably cost test device to characterize the core parameters vs frequency, the magnetic saturation points and such.
I'd been thinking about brewing up a fixture where I could just wrap a few turns of wire through the toroids hooked to a bridge where the tester would sweep the frequency over a wide range while measuring the impedance. This would characterize the permeability and such vs frequency. I could probably match that up with the published spec of common core.
The other issue would be the magnetic saturation point. That would give me an idea of what power levels the core would be good for. Possibility I'd add a second winding into the core and sweep a varying DC current while repeating the RF frequency tests to characterize the core with core parameters vs frequency vs current.
I don't know how well the DC layered over the RF will match proper measurements, but I don't want to have a multi hundred watt RF source in order to test a core.
Maybe only a few simpler tests are enough to determine what the core mix is and then you match the physical dimensions to the standard core data sheets to know what you have.
I assume this ground has already been covered by others.