A couple of people have mentioned how they do inductor Q measurement.
Here's how I do it:

I make a parallel tuned circuit with the inductor and an air variable
capacitor. I've found that even mica capacitors often have a low enough
Q to affect the measurement of reasonable Q inductors. The variable C
also lets me do the measurement at the frequency of interest. I couple
into and out of the parallel circuit with 1 pF capacitors, connecting
one to a signal generator and the other to a 50 ohm termination and a
scope. (If you calculate the parallel equivalent of the coupling cap and
terminating resistor, you'll find that you need either a low or very
high value of termination to avoid affecting the measurement.)

I've now got a signal generator with a digital frequency readout, but I
used to use an old high level generator which I tapped into in order to
hook up a frequency counter. I peak the scope signal at the frequency of
interest. Then I vary the frequency slightly and find the precise center
frequency and the -3 dB frequencies. The Q is simply the center
frequency divided by the 3 dB bandwidth. For ease in making
measurements, I built a simple 3 dB switchable attenuator and put it in
line with the signal generator, terminating the output in 50 ohms at the
Q meter so the attenuator would work properly. I measure the center
frequency with the attenuator in, then switch it out and find the -3 dB
frequencies by adjusting the frequency for the same output level as
before. If you use the attenuator, the detector doesn't have to be
linear, so you could do away with the scope and use just about any kind
of detector like a diode and DVM.

Using this method I get within about 10% of an HP Q meter at HF, at
least up to a Q of 300 or so, which is about the best I usually get with
a powdered iron toroid core.

Roy Lewallen, W7EL

Roy Lewallen wrote:
A couple of people have mentioned how they do inductor Q measurement.
Here's how I do it:

.........

Good method. I have done that before but my current RF sig gen doesn't
have very good output level regulation, nor is the output adjustable -
it's only a one-transistor sig gen after all
They wouldn't let me take my H-P with me when I retired ]
Alan

Alan Peake wrote:

Good method. I have done that before but my current RF sig gen doesn't
have very good output level regulation, nor is the output adjustable -
it's only a one-transistor sig gen after all
They wouldn't let me take my H-P with me when I retired ]

Neither of those should be a problem. The absolute level isn't
important, and the amount you have to adjust the frequency for a single
measurement is small -- for inductors of reasonable Q, anyway -- so the
level probably won't change much over that small range unless the level
stability is extraordinarily bad.

I've got a one-FET homebrew oscillator I made a long time ago with an
extra transistor or two for a crude ALC that keeps it reasonably flat
over the whole HF range. But you shouldn't need an ALC for most Q
measurements.

Roy Lewallen, W7EL