Hi Jim, For high power Balun Applications, most critical parameter is Ferrite core loss which causes core heating. Core loss, parallel resistance (Rp), can be computed from complex permeability data from Fair-Rite.
https://www.kn5l.net/Balun-CM/Balun31-43/ Models FT240 10T with 31 and 43 materials. G.Zo is selected to indicate maximum possible core dissipation watts. Maximum core dissipation accrues when ground to antenna external conductor electrical length = 1/2 wavelength multiples. 1/2 wavelength multiples reflects ground impedance to the Balun. As shown, at 1.8MHz, maximum core dissipation for 1kW key down could be 4W for 31 material and 3.6W for #43 material. Probably not enough difference to worry about. The two CMRR traces, red and yellow, are below about -20dB. Difference in choking ability is insignificant in this range. The model includes a parallel capacitor for self resonance. Though is not critical, as reactance does not result in heating. Core loss, Rp, causes core heat rise. All in all, not much difference between 43 and 31 for these two Baluns. John KN5L On 10/12/20 9:05 PM, Jim Brown wrote: > #43 is a terrible material for the HF > bands. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
