[TowerTalk] VNA

[Jim Brown]

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