Frequency splitting and measuring Q

Richard Quick and Richard Hull have both mentioned frequency spliting
when the primary and secondary are overcoupled. I would appreciate it
very much if someone could explain exactly what splitting is and how it
exhibits itself. I suppose if the phenomenom is present then the solution
is to decouple until it goes away... right?

With regard to measuring Q. It seems to me that someplace I have seen a
formula for Q as follows:  Q = fc / (f1 - f2).  Where fc is the resonant
frequency of a coil, f1 and f2 are the higher and lower frequencies above
and below fr where the voltage drops to .707 of the value at fr. Is this
valid or have I got something wrong ?

As always, thanks in advance for your help
Skip Greiner