<<< To follow on to Todd's question, I am gathering parts to construct the 3.5" Frequent Flyer FSL and have obtained
27 140mm x 8mm ferrite rods (instead of the specified 160mm x 8mm)
45 feet of 1162/46 Litz wire (instead of the specified 35 feet)
1 higher Q 8:1 variable capacitor from Mike's Electronic Parts (instead of the specified 365mm variable cap) >>>
Wow, Chuck, by quite an amazing coincidence I have already constructed a 3.5" diameter Frequent Flyer FSL using exactly 27 of the 140mm x 8mm Russian surplus ferrite rods. I also used the 1162/46 Litz wire, and the higher Q "384P" variable cap from Mike's electronic parts. A photo of the completed model is attached.
As such, I can give you exact information on the coil turns and Litz wire length. The coil uses 27 full turns of the 1162/46 Litz wire, plus about 8 inches on each end as pigtails for soldering to the variable cap. The total wire length would be the 27 coil turns (29 feet 9 inches) plus 16" for pigtails (total of 31 feet 1 inch). The model tunes from 515-1650 kHz, and has an FSL sensitivity score (coil diameter x ferrite length) of 490. This makes it almost exactly as sensitive as the 5" Frequent Flyer FSL model taken to Poipu, Hawaii in November, which tracked down AM-DX from every continent except Europe (FSL sensitivity score of 500).
Gary DeBock (in Puyallup, WA, USA)