Balun Component Sources in U.S.A.
Arrow.com Ferrite Toroids (Fair-Rite/Amidon, Ferroxcube)
Search by manufacturer's part number.
For FT-140-xx cores, search on: 59*002701
For FT-240-xx cores, search on: 59*003801
When I find time, I'll hunt out the Ferroxcube cores and see if I can find them there too.
Kent Coropration Hollow Ferrite Rods (#31)
KF7P Metalwerks Ferrite Toroids and Beads, Misc. Hardware, Heat-Shrink tubing
Kits and Parts dot Com (The Toroid King) A source for many common Toroids.
(Important: Amidon is not a manufacturer, they are a reseller. Don't bother to search on the Amidon part number - i.e., "FT-240-43")
In this case you must search on the Fair-Rite part number, not the Amidon part number.
- FT-240-31 = 2631803802
- FT-240-43 = 5943003801
Everett has compiled a list of Amidon vs. Fair-Rite part numbers. (I'll post it somewhere and update here.)
more to come . . .