Hi Mike.
I suspect that the dielectric loss of your coil is secondary. A Qul of nearly 350 implies to me that the primary losses are likely copper wire R and fixture.
A couple of useful things to do. Place a known R in series with the coil. Deliberate de-Q and return to a measurement on Rs.
The number calculated should make sense. Example, suspect 7 ohms is the "real" number, place a 10 ohm (low inductance R) not a WW, you should
see say 17 ohms. This is simply a sanity check.
Second, in looking at your solenoid coil, the L/D ratio looks wrong for optimum Q. Something like L/D of 0.5 to 1 per Terman is better served for Q.
There is quite a few papers on this relation. But worth investigating if Q is the big deal.
