I had optimized the RF yesterday, but the source went into a dual-mode toggling regime. It is hairline to find a nice point. I also found that it responds better if frequency is approached from high to low.

Later... After some tweaks earlier, beam is looking pretty good, a solid 3enA at FC6.

BTW, we are still running with the same SO2 gas settings as before, i.e. the calibrated leak valve just barely cracked open. Under the circumstances, it's a sweet spot for us.

Later... Another blip on the field probe at 16:15. Coincidentally the beam took a little hit. Here are the Stripcharts (tight zoom and normal zoom).