Hi Jerry!

I have used both 100/44 and 660/46 Litz wire to wrap a 38 turn primary winding on a 19” 125 mu ferrite bar, terminating in a 365 pfd variable capacitor for tuning the MW band. In this context the difference in S units as measured on my Palstar R30a was typically 7 vs S+30 for most stations. There were many stations barely audible with the 100/44 coil that could be really well heard using the 660/46 wrap. I don’t know if this would translate into comparable results with a FSL antenna set up but it sure makes a difference with monster ferrite bar antennas that only have one ferrite rod, albeit one that is 19” long x 1” wide…