I've been studying Nelson's videos and had another look at his radiant box. I think I'm starting to better understand how he got this to work.
https://www.youtube.com/watch?v=fJ0roz9qz0gPlenty of juice to fire-up that big shop lamp.
My take on things:
The white side-by-side bifilar coil on the left is being energized with/by the high-output board with the fan & heatsink. This provides the amps. Not certain what kind of a signal this is, but suspect it is quite similar to an induction cooker.
The board on the right with the yellow-taped transformer is likely the radiant exciter, the output of which probably goes to the blue bifilar coils. This provides the voltage.
The clear side-by-side bifilar coil on the right is most likely the output coil. The entire coil stack is what one might classify as a mixer. This is where volts X amps is happening. The spacing between the two blue coils gooped with silicone likely sets up the proper phase angle so the voltage and amperage signals can mix in-phase into usable output power.
The board on the bottom left could be a separate exciter that drives one of the blue coils, or it could just be the rest of the primary exciter--not really sure as yet. Maybe it synchronizes the frequency of the exciter with the high-output board. Based on it's placement, this makes the most sense.
What I am feeling pretty confident about is the mixing concept here. From watching the videos Nelson has published and seeing the timeline of his development, this concept seems the most likely. Even Nelson's learning circuit had two outputs--high and low voltage, which makes me think he was considering joining these outputs back together at some point in the future. That is something he has successfully done with his pancake coil stack. Sure looks to me like a very logical and well thought out progression that has led to a successful self-running device. In the video above, the universal power supply is only there for testing purposes; it's quite obvious the 24 volt output from this power supply could be looped back in place of the benchtop supply he uses to start the device. This is identical to how the Ruslan device was looped and I know Nelson spent quite a bit of time on that thread at overunity.com--it's a very practical solution that he would implement.
To be honest, I'm not seeing anything in Nelson's radiant box that I would call magical. Everything has a purpose. What I think he discovered how to do is mix volts and amps to get true usable power and it looks like pancake coils is the most straightforward way to accomplish this task.