You cant get current flow in an open circuit
Dave
Perhaps I chose the wrong smiley for my comment?
What I was saying is, that he did not mention a load for the current to flow through.
We now know that the load is, " a short circuit through a ammeter ", ie. a very low DC resistance (probably non-linear) with an indeterminate reactance. (Was it a moving iron meter, a thermocouple meter, something containing diodes or more sophisticated electronics?)
So we have a shortcircuited secondary with some, but very low, output voltage (I'm loosing track of the practical value of this now), which current is trying to cancel the field the primary is trying to create, is increasing the primary current until it is limited in some way by the driving circuitry. Perhaps what we're seeing is some property of his driving oscillator with changing load inductance?
Since we now know he's driving it with a square wave @10kHz, I can hardly begin to guess at the output waveform. Maybe he's getting some sort of resonance effect with his coils: extra iron around the coil is bound to alter that. It also raises the question as to what current he's measuring: my simple moving coil ammeter with diodes says that it is calibrated to give the RMS value for sinewaves from 45 - 200Hz. So what IT would tell me about the output from his system is anybody's guess. Maybe the freakish load means that what he thinks is a 10kHz sqare wave oscillator is operating in some entirely different mode?
If I understand his description (two coils on a long ferrite rod) there is also plenty of scope for variation in magnetic coupling between the primary and secondary.
While I have some sympathy for BC109's suggestion that we try it ourselves, he has not yet said enough to make me want to do it. Like someone inventing a perpetual motion machine, you know that what he says doesn't make any sense. I'm just a bit intrigued to know what it is that he's seeing and to understand how he's being misled.
If I want to do some experimentation, there are other topics on this site that look much more promising and worthwhile that I'd spend time on first.