Arv,

A wonderful instrument to have if your doing any RF measurement.
Team it up with a SA and RF measurements get very interesting.

Yes, the prices are all over the map as it here are clones like crazy.
There are at least three versions as well  (mostly different firmware).

However as a long term user of HP and Agilent VNA and PNA machines
costing tens of kilobucks the nanoVNA is a remarkable tool for pennies.

The number of things you can worth one is nothing short of RF multitools
category.  I use it for filters of all sorts well into UHF, crystal filter testing
and adjustment, amplifier gain, port reflections and such, and cable checks
just to scratch the surface.  When working with power amps you can sort
out input mismatch, output mismatch, and even loss through TR relays
and leakage around them.  My favorite use is S21 mode as output to
reference antenna (simple dipole) and input from antenna under test
(after doing it with reference dipole in the input too).  Collect the data
from that and you can determine the antenna gain in DBD, patterns
of the antenna in any inclination or azimuth at least for antennas 
that you can handle like smaller than 6M beam (really handy for 432
and up).

Once your into smith charts and the  theory it becomes easy to see
how input or output matching works and how to move around the
impedance circle.

The connector used is polarized but symmetrical dual contacts so there
is no upside down.   Or as I call it yet another USB connector (YAUC).

Allison





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