On Dec 14, 9:10 pm, "AI4QJ" wrote:
Where did the extra black box come from and who made the restriction on
frequency? I should be able to use any voltage or frequency I want, don't
you think?

The original problem statement discused -j567 as
an impedance. This is implicitly frequency dependant.

The Smith chart is normalized for impedance
and frequency.

When allowed to excite the black boxes with different
signals there are many ways to determine an internal
equivalent circuit. The question here was did the various
ways of making -j567 affect the results for sinusoidal
single frequency excitation.

....Keith