[jrblasde]

Thank you for double checking me! I do appreciate it. I went to bed last night thinking that microfarads just didn't make sense.

Alright, so where did I go wrong? Two days ago I had written that C = [1/( 2*pi*f*sqrt(L) )]^2 for a resonant LC circuit, and that is correct. Mid-day yesterday I was away from my notes and wrote down C = 1/( 2*pi*f*sqrt(L) ) (note the lack of the final square) from memory rather than re-deriving the equation. Rookie mistake! Thus, I came up with 3.729 µF. If I square this, I get 13.905 pF. That's what I was missing! This matches 462ron's findings.

Lesson of the day--always derive the equation rather than recall it from memory!

Attached is the revised schematic. We'll be back to the original issue of potentially touchy adjustments now that we're back in the range of adjusting by just a few picofarads, but I will start with this. A fixed 10pF capacitor in parallel with a 5 pF trimmer. I'll get a better understanding of the parasitic capacitance introduced from the surrounding can, as well as the plate and grid capacitance for the primary and secondary sides, respectively.