For about four years, I've been using the VNWA 3e, designed by German EE
prof DG8SAQ and built by some hams in the UK under the name SDR-Kits.
It's not a kit, it's fully built and tested. I paid about $770 then,
delivered to my door, with calibration loads and a carrying case; thanks
to Brexit, it's about $100 less today. It's quite well supported both
by SDR Kits and by DG8SAQ via an email reflector. In addition to the
standard VNA functions, it does excellent TDR by taking the inverse FFT
of a wide sweep. The unit has full spec to 500 MHz, and reduced dynamic
range to 1.3 GHz.
The file export functions work well, there are built-in math functions
that can, for example, transform an SWR sweep to 75 ohms. The unit is
also supported by AC6LA's excellent Excel spreadsheets. SimSmith and
most of AC6LA's spreadsheets are freeware. I regularly use his ZPlots to
compute the fundamental parameters of coax by importing S11 data from
the VNWA into ZPlots.
I regularly make Z measurements of antennas in the shack, measure the
line with TDR to find its length, and export the data to SimSmith to
transform the measurement to the antenna's feedpoint. I also use TDR to
look for any problems along a transmission line. The unit stores
multiple calibration files, so once you've done a calibration for one
measurement setup, you can recall it on another day without the need to
redo the calibration. The measurements in this report were done with the
VNWA 3e.
http://k9yc.com/BandpassFilterSurvey.pdf
So were these measurements of DX Engineering's excellent NCC-1 phasing
unit.
http://k9yc.com/VE3DO.pdf
73, Jim K9YC
On 10/30/2017 5:29 PM, Neal Sulmeyer wrote:
My MFJ 259B is 25 years old and obsolete. Time for an upgrade. I'm
considering the AIM 4300 (updgrade to the AIM4170 recommended by ON4UN).
I would like to hear some opinions on this device and others from my fellow
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