Topband: Mother of all ferrite common-mode coaxial chokes

[Richard (Rick) Karlquist]

Another thing you can do to measure chokes accurately is
to simply use a Vector Impedance Meter instead of a network
analyzer.  Like the HP 4815A.  In essence, it uses the VI
method, as the name implies.  It doesn't care if the
impedance is nowhere near 50 ohms.  For really high
impedances, it can be helpful to mathematically subtract
the stray capacitance of the probe.  I've gotten excellent
results with my 4815 for years.

Rick N6RK