I thought I'd start a new thread RE inductance of FT37-43 toroids.? I just measured the inductance of an FT37-43 wound with 10 turns #28 wire.? Measurements at 1, 2, and 7 MHz. using the series resonance method. Inductances measured were 38.5, 35.8, and 20.2 ?H.? This corresponds to calculated Al's of 385, 358, and 202.? The Q is very low for coils wound with these ferrite cores and the dip at 7 MHz was barely discernible.? The lower Al at 7 MHz is consistent with the roll-off of the material permeability starting at about 2.5 MHz or so.? Also if you look at the coil winding data on both Amidon and Kits and Parts sites you will see that the inductance values for a given number of turns is around 20% higher than a calculated value using their published Al numbers.? This all relates only to the type 43 material.?
