Okay, I've read the dox but am still in the dark as to what *you* use
yours for. What makes it so indispensible?

When was the last time you needed to know a capacitor value AT the
frequency you're going to use it at? (the "C" minus the "L" of the leads)
Or the passband of a filter and it's IL and it's skirts and it's blowby and
it's group delay and it's terminating impedances?
Or needed dual high level isolated oscillators to make Ip3 measurements on a
receiver or transmitter?
Or have a precision sweep generator and trigger for a Spectrum Analyzer?
Or needed the inductance of an inductor AT the operating frequency? (The "L"
less the "C")
Or needed the series and parallel resonant frquencies of a crystal and the
Rs of same and it's "Q"?
Or needed the "S" parameters of a small signal transistor?
Or wanted to know the impedance of your antenna at the shack end of the
coax. Or, if you were smart enough to log the length of coax when you
installed it, the impedance AT the antenna?
Or needed the Zo of a length of coax?
Or the gain of an amplifier over it's frequency range and it's 3 dB corners
to the 0.01 dB?
Or needed a quadrature signal source to be the LO of that new I-Q receiver?

Or-or-or

It's a lab in a box.

W4ZCB