41G wire compared to 42G

[Antigua]

An ideal capacitor has an impedance response of -6dB/octave or -20dB/decade. Far above the resonance a parallel resonant circuit like a PU behaves purely capacitive. Closer to the resonance the decay is steeper, so a C-meter would read a higher "apparent" capacitance.
For PUs having a smooth -6dB/octave slope at 100kHz I could confirm the LCR capacitance measurements at 100kHz with a 40MHz HP impedance analyzer.
The resonance Q of the PU doesn't matter as long as there is a -6dB/octave slope at 100kHz.

Is 40mHz a satisfactory test frequency? If the requirement is that the slope become a steady -6dB/octave, at about what frequency is that expected to be seen? How about, say 20kHz?

[Helmholtz]

Is 40mHz a satisfactory test frequency? If the requirement is that the slope become a steady -6dB/octave, at about what frequency is that expected to be seen? How about, say 20kHz?

It is not a single frequency measurement at 40Mhz. The impedance analyzer evaluates the complete impedance and phase response between 10Hz and 40Mhz and calculates the components of the equivalent circuit from the data.

You can find the minimum measurement frequency from the impedance response graph using a ruler.

[Antigua]

It is not a single frequency measurement at 40Mhz. The impedance analyzer evaluates the complete impedance and phase response between 10Hz and 40Mhz and calculates the components of the equivalent circuit from the data.

You can find the minimum measurement frequency from the impedance response graph using a ruler.

I'm talking about an LCR meter like the DE-5000 that offers some particular test frequencies, 100Hz, 120Hz, etc.

For the sake of conversation, if the DE-5000 had a test freq between 1kHz and 100kHz, what would that minimum be in order to test capacitance of a pickup with a resonant peak around 10kHz? This is important because better, cheaper LCR meters will probably hit the market over the coming decade.

[Helmholtz]

For the sake of conversation, if the DE-5000 had a test freq between 1kHz and 100kHz, what would that minimum be in order to test capacitance of a pickup with a resonant peak around 10kHz? This is important because better, cheaper LCR meters will probably hit the market over the coming decade.

As said, you need to find the minimum test frequency from the linearity of the slope of the impedance response. 20kHz is most certainly not high enough with a 10kHz resonance.
100kHz was good enough for the PUs I tested.