Martin, G8JNJ constructed a balun using 35 turns on a FT240-61 core and measured the choking impedance using AIM470.
Fig 1 shows the modelled Rcm, Xcm and Zcm, and measured Rcm, Xcm and Zcm. The model was calibrated with 1.3pF of shunt capacitance to exhibit a resonance at about the same frequency as the measured balun. The measured R and X value is a little higher than the model above resonance, converging with increasing frequency. Otherwise there is close agreement between model and measurement.
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