The ability to calibrate the feedline 'fixture' as part of a VNA
measurement system provides the convenience of measurement referred to
your preferred reference plan. The AIM4170 is (as I understand it) half
of a VNA, but that should be enough to do the same thing.

So, for the advantages of the ham grade VNA over the MFJ259B, you pay
more money, get better measurement resolution (the AD converters have
better resolution than the MFJ259B), have capability for automation of
measurement referred to a convenient reference plane, but... you lose
portability... though there is no reason why a ham grade VNA with a basic
display system couldn't be portable.

Owen

The fixture cal is a pretty standard feature of all the ham VNAs (AIM
4170, TAPR VNA, N2PK) whether one or two port devices.

Making it portable is something I've been toying with.. The software is
not that complex (at least for the TAPR VNA), so running it on a PDA
velcroed to the top of the box isn't out of the question. One problem
is that the TAPR VNA is a USB slave, and most PDAs can't be a USB master.

Maybe a small touchscreen netbook? Granted, you're now talking $1000 for
the complete setup, but you'll have a real portable powerhouse, much
like the Anritsu SiteMaster at 1/10th the cost.


http://www.us.anritsu.com/products/S...QSidZ1016.aspx


I've also contemplated making something like a S-parameter test set for
the TAPR VNA (so you can do both directions) with a built in eCal.
Basically just high quality relays and terminations is what's needed.

Another useful add-on would be something that turns the VNA into a
spectrum analyzer (e.g. use the output as the LO to a mixer followed by
a BPF).. There's a lot of other problems with this, though.