Your idea needs one change to give you a comparison between the two caps.
I think you are making the frequency adjustment in the wrong place.
You need to adjust the frequency of your frequency generator and watch your S meter until it changes by *usually 3 db.
What's wrong with tuning the rig to find the 3dB (or 6dB=1 S-unit) points?
If you have a scope, I will post a method I have used dozens of times.
No scope, but plenty of curiosity. What's your method?
If you tune the rig, I think it tells you more about the IF filter in your radio
than the Q of your Loop.
It's late, I copied this from another thread I posted in 2006.
Read it and if you have questions I'll review it tomorrow and see if I can clarify.
You need to lightly couple some energy from your signal generator into the
resonate circuit. This can be done by placing the generator wires near the
resonate circuit close enough to get the scope signal level you need but as
away as possible so you don't load the circuit. You can couple it with high
value resistors if desired, but this increases loading on the inductor.
Then I adjust coupling and signal generator output to get 7 units
on the scope. Why 7 units? I'm glad you ask! You want to move the signal
generator frequency up until the voltage on the scope drops to 5 units.
Some explanation; We want to measure the upper and lower frequency points where the voltage drop is 3db or .707 times the resonate voltage.
So, back to the 7 units, .707 times 7 units equals 4.949 units or 5 units
when I'm looking at my scope.
So we adjust the signal generator frequency to peak the waveform on the
Let's say the waveform peaks at 1,596,200hz.
To get the 7 units sometimes I adjust the generator drive and sometimes I
change the scope variable attenuator.
I move the frequency up until the scope reads 5 units, Record this
Lets say it's 1,600,200hz
Now move the frequency down until the scope reads 5 units, Record this
Lets say this is 1,592,219hz
Do the math 1,600,200 - 1,592,219 = 7981
then using the resonate frequency of 1,596,200 / 7981 = 200
The Q of your inductor is 200
I think I got this all correct, it has been a few years since I did this. I
used it a lot when I was
trying methods to improve the Q of some potcore inductors.
Let me know if you have questions.