I'm playing with rather more exotic HW, a Tek 11801 & SD-24 TDR head which is a ~26 ps rise time TDR evaluating the quality of Chinese RF connectors. But the principles are the same and I'm very interested in using the nanoVNA for such things. I'm a retired seismic research guy, so I've been having a blast. Most fun I've ever had with a piece of test gear and all I'm doing is playing.
I look at the time domain S11 and the time domain S21 response. The S11 TDR shows any discontinuities and the rise time of the S21 TDR gives me an estimate of the frequency limit. In my case I'm putting the connectors between a couple of pieces of RG402 terminated with SMA-M connectors.
If you do an SOLT on a short known high quality cable, then substitute the CUT and repeat the SOLT at the end of the CUT you should get a very accurate picture of cable and connector quality. In the frequency domain there should be a linear phase shift difference between the reference cable and the CUT. The ratio of the S21 values should give you the loss.
I can't keep up with who's done what on this topic in the nanoVNA FW & SW, but the MATLAB clone, Octave is an ideal tool for taking data via the nanoVNA console and analyzing it. The frequency spacing determines how long a cable you can test. 1 MHz spacing will give you the ability to test to 100 m. The resolution is dependent upon the maximum frequency. So 901 points from 1 to 900 MHz is probably a good choice of sweep parameters. You'll need to use the reference cable results to compensate for amplitude errors in the nanoVNA. If you pad lots of zeros on to the end of the frequency domain measurements you will get very fine sampling in the time domain.
I recommend doing this with bare uncorrected data at least once using Octave just for the educational experience. It's actually *very* simple. And there are plenty of people here able to help out.
I used the 11801/SD-24 to test another APC-7/N-F adapter yesterday from the same seller as in the photos here:
Comments on second sample:
I've still got tests of BNCs and other stuff to do with the 11801 and then I'll be duplicating some of the tests on the nanoVNA and my 8753B.
Have Fun!
Reg
