How to tell if you have a bad NanoVNA

This was a fun journey/project to play with and I learned a lot. Let me share the journey with you and how you can tell if your Nano is good or not.

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0:00 Intro
0:56 Touch Screen Problems
4:05 Sweep an Antenna
5:30 Comparing against a Good NanoVNA
7:20 Firmware Update #3
9:45 Switches to Center Mode?
10:38 Physical Comparison
13:24 Test Dummy Load on the K9WEN Unit
14:24 NanoVNA Test Procedure
19:00 Bad NanoVNA
22:33 Conclusion
23:19 Thanks for Being Awesome!

[randyslaten]

Don't know if this is the best place to rant about this, but here goes...

Make sure to select DISPLAY->CHANNEL = "S11 (REFL)", not "S21 (THRU)", for measurements like SWR and SMITH charts made on PORT 1 (S11).

For HF calibration, use 1 MHz -to- 30 MHz stimulus range:
STIMULUS->START = 1 MHz, STIMULUS->STOP = 30 MHz.
By all means use a smaller range for higher accuracy if necessary.

Always reset calibration data before performing another one: CALIBRATE->RESET.

Perform Open-Short-Load calibration and save result:
0".
All settings and calibration data stored in "SAVE 0" will be loaded upon power-up.

Verify good calibration by placing Open-Short-Load devices on PORT 1 and observe that "dot" position appears at right-left-center on SMITH chart center axis.


If calibration was done right at the SMA connector on PORT 1 but an open coaxial jumper and/or adaptor is later added, the SMITH chart will show a rotated arc instead of a "dot". By introducing an electrical delay the calibration reference plane can be moved to the end of the jumper/adaptor to compensate.
Automatically: MARKER->OPERATIONS->E-DELAY
Manually: DISPLAY->SCALE->E-DELAY = "value" (+/- nS or pS)
Re-save to include in location of choice, e.g. "SAVE 0", "SAVE 1", etc.

[MidlifeRenaissanceMan]

I picked up a used Nano VNA F that had some similar issues. Buttons were all out of whack, but calibration was fine. I replaced the lithium battery and now it works like a champion. Problem free.

Try replacing the battery, or giving it a reliable supply

[Numberlead]

I bought a nano VNA on amazon. I have attempted to build several antennas from quagis to moxons to j poles. My vna always measured poor to mediocre performance. I always assumed I did something wrong, although I measured everything to a T. Now I'm wondering if my vna is faulty all this time. I'm going back to the good old reliable SWR meter.

[nmail]

I've had mine for several years now. I've always made excuses for why it sucked. It works. But it makes you pay patience to get results

[barrykery]

My NanoVNA H4 is build time Jan 31 2021 Version 1.0.45 and I don't have any issues at all. I have a RIG Expert AA-230 Zoom, AA 650 and a SARK 110. All four give me pretty much the same readings. This is not the firmware version that came with mine. I bought mine from R&L Electronics thinking they did their research before they went out and bought junk. I also purchased the TInySA from them. The TinySA had a slight glitch on the display on 40 meters when I narrowed the span down to 10 khz. I updated the firmware and the little glitch went away.
Your video was very interesting and glad you posted it.
Barry, KU3X

[jeffreyfritz]

You have descirbed exactly the way that my NanoVNA is acting. It acts like your bad one. R&L is replacing it with a newer version. Your video and testing was immensely helpful! 73

[ToNzHoLtZ]

My nano vna was glitching until I installed the new firmware, and it now seems to work okay, except for the fact it does not have a DTF option ..

[bertbronson]

I am curious as to why the curves werent flatter given the swr was set to 1.0/ division on both devices (later in the video) instead of the 250m/ division you had on your device at the beginning of the video. 1.0/ gives a full range of like 10 vs 250m/ a vertical range of 2. That may not affect the readings or results, but it is curious...

[rilosvideos]

I am missing the red thread in test test procedure - looks more like try and error. Its essential to have proper shielding in place (esp. for higher frequencies) and to have a proper calibration first. When i buy from ebay or ali how can i know what i get? You probably should omit the lowest price offerings ;-)

[astrawally]

My biggest learning with these is that you need to be wary your own interactions and how they impact what you are measuring (capacitive coupling, induction effects etc), how well it is shielded (your Norcal looks hip but it is not shielded) and any grounding effects.

The NanoVNA uses a few mW of power to make its measurements/sweeps, it doesn’t take a lot of interference to impact those.

To show this, get your good NanoVNA and connect a known good VHF/UHF whip. Find best VSWR and start to interact with it.

Point here is that there are so many factors at play that it is going to be difficult to blame the NanoVNA purely.

I do agree with the other comments about battery and firmware updates but I don’t believe that any one supplier or manufacturer is intrinsically building dud hardware beyond the odd faulty units.

[PhilLeith]

I have one a friend gave me ... and I am getting results I would not expect. SWRs in the 10:1 range in the range this dipole is cut for. I'm thinking maybe it's a bad one

[Screamingtut]

mine comes up with the Blue logo like your friend's NanoVNA. I cannot read the version because I did not have my reading glasses handy.

[vidasvv]

How does it compare if u slap a 75 or 100 ohm load ? tnx 4 the upload! 73

[DonzLockz]

what was the end result? Did you return it?

[TonyLing]

Can it actually be counterfeit? I understand that it is an open source design.
My H4 behaves in a similar way. The interface can be unresponsive, and the measurements are not consistent. I think I'm going to buy a V4.

[Tommyr]

I just bought one on Amazon and can return it if it doesn't work right within 30 days. Need it for VHF/UHF antenna testing. I already have an AA-55 zoom for HF.

[jamescoleman]

Try and remember to ground the coax before connecting your vna or other kit.

[Randy-xswm]

I actually need to buy a NanoVNA and would appreciate your recommendation (link) for which one to buy. By the way, affiliate links are ok with me (because the price doesn't increase for me if I use a link you sponsor, AND I get to support your efforts as well)!

[peterdekeles.]

Would love to see a video on updating the firmware

[tmiller]

Do you need to set the range/stimuls before calibration?