Hi Ray,Thanks, that's great info. Far fewer turns on your primary than I would have expected. When I took radios apart as a kid, I remember the "Wave-Wound" LW coils with a couple of hundred turns or so of Litz wire, enabling something like 150-280 kHz to be tuned with a 365 pF capacitor.
Recently I was reading old "Practical Wireless" magazines available on the WOrld Radio Heritage site. A design for LF used a small audio transformer to couple a loop antenna. This makes me wonder if the laminations used for audio chokes (experience gained making speaker crossovers) might make LF antenna "rods". If not, perhaps VLF.. They won't have the high permeability of ferrite, but could be cheaper and more easily available.
Of course a larger cross-sectional area, filled with ferrite gets more uH wit fewer turns.
Interesting stuff, and a great conversation.
Cheers
Ed