Is this an Impedance Matching Curve?
So I retried the simulation using a 80uF capacitor in parallel to the transformers output and I appear to now be getting roughly the same curve although circuit lab spits it out using log on the x axis







simulate this circuit &ndash; Schematic created using CircuitLab

This is the simulation result: 



So that seems to be accounting for the curve i see experimentally but could someone please point out what is happening here? 
Its starting to look like the secondary coil is being driven into resonance by the primary coil....

Thanks