Jet from my understanding Rick had an scr/cap setup on the back end, but it was not pulsed. I could be wrong, but that is the schematic I have seen and studying his pics I can see no 555 timer or opto isolator.

My latest build employs this technique, with the scr on the positive leg (Ricks was on the negative I think) and I wonder if this qualifies as a conversion of the radiant which allows for battery swapping. The cap converts the high voltage and is an extension of the dipole, it usually hovers at a volt over the charge battery. Ill make a little video to show it today.