Hi, I am in the process of trying to develop an air transformer but encountering unusual behaviour which I hope can be explained with some fundamental theory I don't yet know. My set up is as follows; - Two identical wound 13.3uH inductors designed to resonate at 4.364MHz. They are 10 turns, 2mm pitch, 100mm diameter, 1mm core. Each coil is designed to be part of a series LCR circuit where the capacitance is 100pF, and the resistance is 100ohm. - The primary coil is powered by a 20Vpp signal generator, 50 ohm output, using a co-ax cable with measured capacitance between the lines of 90pF. - I am not sure of the full effect of the transmission line capacitance which would be parallel to the LCR circuit, but to compensate I have used a variable capacitor (instead of the designed 100pF) to tune the primary back in to 4.364MHz. - The secondary side is a closed LCR, 13.3uH, 100pF and 100ohm. - I am using two separate oscilloscopes so that no grounds etc. are shared to confused measurements. The confusion: I am trying to measure current through each of the 100ohm resistors to infer the mutual inductance, co-efficient of coupling and efficiency. This is done by measuring the voltage across the resistor and then using ohms law. Measurements show that at close range less voltage and so less current passes through the resistor in the primary circuit than the resistor in the secondary circuit. This would hint at more power out than being put in would it not?