Hi Joe (and Steve),

Thanks for posting the link about the 3.125" x .39" ferrite rods for sale from Electronic Goldmine.

They sound interesting, but in comparison to the Russian surplus ferrite rods (sold on eBay) commonly used for FSL antenna construction, their relatively short length would make their performance similar to that of the 62mm x 8mm Russian surplus ferrite rods, which were extensively tested in many FSL antenna designs during all-out experimentation for a 2012 article (posted at https://dreamcrafts.box.com/s/mr7aec2o4fid5u4dc48xz0t6u9uto8xh

Back in 2012 (a year after Graham Maynard of the U.K. introduced modern FSL antennas) there were multiple controversies about whether ferrite rods or bars were superior, whether long ferrite rods or thick, solid ferrite was superior, whether huge diameter FSL coils with short ferrite rods could outperform smaller models with longer ferrite, etc. The article linked above was an all-out effort to honestly evaluate all possible FSL antenna configurations by recording their weak signal performance on fringe daytime DX signals, comparing the recorded signals against each other in switched A/B tests, and posting the MP3 recordings to back up my conclusions. This article was the experimental basis for the "FSL Antenna Sensitivity Score" conclusion-- that the relative sensitivity of any FSL antenna can be determined by multiplying the coil diameter by the length of the ferrite sleeve, as long as all other factors are identical (ferrite permeability, ferrite manufacturer, type of Litz wire, etc.).

So for the short ferrite rods for sale from Electronic Goldmine, since their size is similar to the 62mm x 8mm Russian surplus ferrite rods used in the "short rod" designs in the article, you can be pretty sure that their FSL performance would be similar (i.e. the least sensitive of all the different FSL designs).

Gary DeBock (in Puyallup, WA, USA)