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I have 2 NanoVNA, one bought from AURSINC on Amazon, which I originally thought was not a knockoff, and one bought from a link provided by Hugen, that I learned of only after getting the AURSINC and finding this forum.
I set up both units (AURSINC on left) with the same traces and freq range.
Both are running Q-0.4.3.
I calibrated both units with ~3.5m RG316 connected to each port, and 2 50 O terminators.
Immediately after each calibration, I put on a 50 O cal terminator, and took the picture.
Exclude image quality...I took the images w my mobile, and they are notoriously easy to lose focus at close distances.
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73 de Rich NE1EE
On the banks of the Piscataqua

You have connected the 50 ohm load to CH0 and you are looking at noise on CH1
More noise implies better isolation and that is what you want
(I think....)


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Erik, PD0EK

Yes, for whatever reason you got a lower apparent reflection coefficient on the left-hand unit.
This is reflected (so to speak) in the noisier-looking phase trace.

Results with an S21 measurement of a fairly lossy DUT (say, about a 30 to 40 dB attenuator)
should be more revealing of the relative merits of the two units.

Dana (K8YUM)

More images, a puzzle, and some explanation...like real estate, it may be location, location, location
To begin, it's true that I was open on CH1, but the image shows that both devices were displaying only CH0.
Perhaps I should have CH1 capped at 50 O? Not sure, but will test to see what difference...

Now puzzle: I arrived back and decided to do some checks. I was surprised to see change to LOGMAG signals on H. H_Q-0.4.3_20191114_173035c.jpg
I recal, and duplicated the test, being careful to lay out the 3.5m of RG316 with no overlaps. Surprised to see H_Q-0.4.3_20191114_174614c.jpg, because now the phase had a lot of jitter.
As I was moving the unit off the desk to take a better picture, the signals cleared up. Not sure why that is so...No running electronics on desk, but the desk is covered with a dark tempered glass...it may have metal in it.
Seeing the effect of raising the H VNA from the desk, I wondered what the AURSINC unit would look like...in my original post, it was very much worse. But see AURSINC_cf_H_Q-0.4.3_20191114_174939.jpg.
I didn't recal the AURS. The phase is now cleaner, and closer to H, but there are those odd humps in LOGMAG.
I note there is a 180 degree phase difference twixt AURS and H in both my original post and this one, and don't know if that is important.

I am preparing to use this in the field, so I want to know what my expectations are. I also am trying to figure out if it is possible to put this at the mid-point of a 130 ft. plus dipole fed by plastic window "ladder line" to measure feed point impedance vs frequency and how it varies as we pull up the antenna from ground level to full height. The alternative is to cal to the end of the ladder line, but I don't know how that will work...to new to VNA.

I also plan to test identical configurations using a laptop|USB and a mobile|tablet|USB to see how data gathering this way affects the displayed data.
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73 de Rich NE1EE
On the banks of the Piscataqua

Yes, for whatever reason you got a lower apparent reflection coefficient on the left-hand unit.
This is reflected (so to speak) in the noisier-looking phase trace.

Results with an S21 measurement of a fairly lossy DUT (say, about a 30 to 40 dB attenuator)
should be more revealing of the relative merits of the two units.

Dana (K8YUM)

On Thu, Nov 14, 2019 at 06:48 PM, Dana Whitlow wrote:

Results with an S21 measurement of a fairly lossy DUT

Because I am new to all this, I'd need some specifics about that.
This thread is comparing what is apparently two VNAs from different Chinese sources. I will pull the case in a few days and compare both internals.
Meanwhile, I used the earlier cal, and mounted an MFJ-1714 tele antenna on a tripod at the end of 3.5 m of RG3416.
AURS left; H, right. Very similar, I think? I made the mistake of not setting the AURS marker on 146 MHz, as I did for the H..
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73 de Rich NE1EE
On the banks of the Piscataqua

On Fri, Nov 15, 2019 at 01:48 AM, Rich NE1EE wrote:

because now the phase had a lot of jitter.

this "jitter" is just because phase has noise. The phase is limited to -180 to +180 degree, so when it come to -180, you will see jump to +180. Unwrapped phase will not have such "jitter"