I think that the resonant scanning circuit is not very very necessary since also in stans design there was the manual scanning, and so as the lock in, as it was used as a logic stage to implement the resonant scanning circuit.
I know this pll will work cause is the same i used in the past for my resonance experiments and when you adjust the knob to the resonant frequency you can actually turn of the circuit and turn on and you will see that the circuit get into resonance automatically.
You can see this in my youtube channel. in the power video.. Is the same circuit but have some improvements now...
The pll senses the frequency and adjust automatically the frequency if it is in the lock range, so basically you need to adjust the lock range so it is able to lock to the resonance. Usually the center frequency should be the resonant frequency so the lock vary in higher or lower frequency depending of the variation of the resonance frequency...
I don't remember well now but i think that R2 define the lock min frequency, and R1 the max frequency so if you adjust the R2 you will change the center frequency...
Of course when we achieve the resonance we can tune the pll to improve its performance...
I think that the resonant scanning circuit is just to speed up the lock in.. Normally this min time to lock would depend on the filter design, but if you disconnect the filter like the scanning circuit thru the logic of the lock indicator do, you are able to get around this min time, thats why i think stan implemented the resonant scanning. I think that he used a relatively big capacitor for the filter to ensure stability of the resonance what would makes this lock in time to be very big, for a practical use like in an automobile, for testing is not necessary. I believe...
