Update : Over 1 foot not counting curves.
Watch on youtube.com
https://www.youtube.com/watch?v=KO4VceLEwWw
Primary: 6.5 turns of 14 AWG on a 3.5" PVC former
Secondary: 2.5x8.5", 36 AWG with a 2x8 (amazing1) topload. Resonant frequency is ~220KHz
Secondary resistance is 540 ohms.(not a onetesla secondary) I have had flashover at the top
of the windings so there could be some breaks. Wish I had a before and after spec.
You can see from the pic I had to modify the board due to several igbt failures.
I was using Steve wards interupter with burst mode. It works good with
his sstc and drsstc coils but the pulse width goes way to long for this coil.
EDIT: I added some protection circuitry to my board.
I first installed a pair of MUR860 freewheeling diodes across each IGBT. Still lost a pair of IGBTs
Next I installed a string of 1.5ke220 across each IGBT. After that last change I havent lost a single thing.
I think my bus caps were "ringing up?" and exceeding the IGBTs 600 volt rating.
A snubber cap might also be a quick fix to help with any slight tuning issues.
Edit 12-27-2013 : Picture of primary scope pattern.