Steve Ward Mini SSTC testing

This is my first go at a Steve Ward circuit which uses the antenna feedback and half bridge. Right now nothing is enclosed, it's mainly on breadboards, and all the circuitry is just sitting next to the tower exposed. I have the circuit wired up per the schematic aside from the interrupter portion and I'm using an old coil of mine I had as well as IRFP460 mosfets to give me more voltage headroom. I started testing at 30VDC, then ramped it with the ZVS supply up to 100VDC, then ended up driving it from full rectified mains through a dimmer switch.

Out of the 3 GDT setups I tried initially I was only really able to check waveforms at lower frequencies and trial and error them when running, they all seemed to work roughly the same with the most important adjustment being the antenna setup in relation to what I did with the bottom of L2.

I'm actually happy with the first results given the janky setup. Important thing to note is what happens when I accidentally short my antenna to the bottom of L2 via a small flame. The output was insane for that split second, I couldn't get it on camera but I saw it out of the corner of my eye, a bright brilliant orange-purple discharge that would have annihilated my breakout wire if it stayed streaming. Soon as I saw the wire catch fire I went for the off switch and just barely caught the larger breakout before I hit it. Now, how to replicate that without destroying the circuit?

So far I know it draws almost nothing because my ZVS supply can feed it 100VDC all the way up. Getting it to pull what I want it to should result in some decent output.

[dirkk]

thats not bad at all ! well first things first, get that circuit on anything other then the breadboard as its going to seriously pick up other frequencies and other garbage ! but im sure you know that :-) if you have an old telescopic antenna, try it out, you can get the optimal position and height for the coil, sstc setups use short and fat coils just like your other setups but i know you said this is a test setup so roll with it, the dimmer is acting as a chopper circuit, its something i wanted to try too and i like the sound .. it could also be affecting your circuit but that might be the fault of the breadboard and its your only source of variable mains but if the circuit can go full power, try it without the dimmer and see how it works ... you can try a large piece of flat wood wrapped in alu. foil for a ground plane or some large hunk of metal ... hope all this helps !