[Amps] grid resonance

[Peter Chadwick]

Actually, the GDO won't measure a parallel resonant circuit!
Just consider what happens. We'll put a coil in parallel with a capacitor, and couple (magnetically) the GDO to the coil. The magnetic field from the GDO coil induces a current in each turn of the coil to which it is coupled. The current induced is in series with the coil, and so the circuit is really a series resonant circuit, not a parallel one. The same thing happens with link coupling to a parallel L and C.
For most practical purposes it doesn't matter, because when the Q is greater than about 5, the difference in resonant frequency between series and parallel is minimal and may be ignored, although with low Q at VLF it can have interesting effects.
Again, in reality. a component with inductance and distributed capacity can show resonance on a GDO, merely because the distributed components  resonate somewhere.
Awaiting the flames!
73
Peter G3RZP