After taking the PLL SSTC 1 out of the closet for fun one day, it suddenly didn't work! The windings on the secondary had expanded while in storage, causing some turns to overlap or get tangled, and the PLL was somehow out of tune. So I refurbished the secondary, and set the PLL range again. Still the results weren't as impressive as I remembered, so I gave the coil a complete overhaul. First I put a ducting topload on, which reduced the secondary fres from 500kHz to 250kHz. The only changes in the driver circuit was changing the timing resistors to 3.3k and 10k from 12k and 16k respectively, and increasing the timing capacitor size from 330pF to 1nF. The 12V SMPS was also changed to a good old fashioned linear supply, and this stabilized the streamers greatly. Since the GDT was far from ideal to begin with and now obsolete due to the low frequency, I made a new one with 5-windings to support a full-bridge. With a lower drive frequency and more primary voltage, I had to make a new primary as well. Tuning it took a great deal of time as flashovers occurred frequently. Eventually I found that simply dumping all of the required turns at the base of the coil was enough to get the best coupling and avoid flashovers. With all the new jazz I hardly thought a mere board was enough to contain my new coil, so I modified an enclosure intended for an old flyback SGTC project. In the end, the refurbished SSTC 1 turned out the be a whole new coil, the PLL SSTC 1,5.