I'd like to know what realistic or reasonable values for coupling coefficients (k) might be in ferrite switchmode transformers. I'm interested in forward converter power range of 50 to several hundred watts.
I'd be interested in typical values for suitably-sized toroids, pot cores, E-E cores and U-U cores. Bifilar and/or surrounded windings (e.g. parallel windings above and below another winding) may be used.
Anybody have any experience with this?