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I caught a YouTube video on these and I am very interesting in getting one for my shack however I know next to nothing about them. I have several antenna analyzers for my ham radio equipment and these look like they could be an interesting tool. I have looked on Amazon and there are a number of these with different names and models. They range in price from $35 to $80. How do I determine which ones are good and which are bad?

My Youtube channel is hamrad88 and my name is Tom Stiles

Thanks for your time.

Do a search in this group for "Place To Buy".

I lucked out and got a good one (included battery and shielding). I have a second one on order for $17. Time will tell if I get a good one, bad one, or none at all.

On Tue, Oct 8, 2019 at 11:29 PM, trrs73 wrote:

How do I determine which ones are good and which are bad?

They almost all identical. Some of them come with RF shileding, some without. But you can make shielding by self from an old tin can.

More important thing, which needs to be taken into account is calibration kit and accumulator, they may be missing, but you're need it.

Don't buy those devices which have marketed as 800 MHz or AA 2 tracks, they may have worse si5351 which cannot work at 300 MHz, this is why they marketing it as 800 MHz. The firmware for 800 MHz is designed for worse quality si5351.

All NanoVNA has the same hardware, and you can install any NanoVNA firmware on any NanoVNA hardware. But some of them may be produced with worse quality components and this leads to potential issues. Such as unstable work, problems with display, etc.

So, the check list is the following:

1) ask seller, if device is 900 MHz 4 tracks and not 800 MHz. There is no guarantee that 900 MHz is not 800 MHz version with 900 MHz firmware, but at least you can minimize risk to catch 800 MHz version. 800 MHz version also works, but it has smaller frequency coverage because it uses worse quality si5351 which cannot stable overclocked at 300 MHz.

2) ask seller, if device come with accumulator and calibration kit

3) see seller rating, purchase count and refund guarantee.

If all is ok, you can safely buy it :)

Howdy Tom, and greetings to the group!
I'm also a newbie; just received my nanoVNA 2 days ago. I ordered one before reading anything here; went a bit up-scale on the price, and lucked out and got one of the good ones. Ordered from lemontree017, a US-based seller on ebay. It was ~$60 f/s, +tax, ~$64.50. There are many listings that are cheaper, in the $40-50 range on ebay, and most (if not all) of them do not include batteries and/or other bits (read the fine print), and are probably the inferior clone units.
The one to look for (in seller pictures) has the black covers, with bright white "nanoVNA" and port labels, (not light gray labels or white with gekko), and has shielded inputs, though I did not see any ebay sellers that show them with back cover removed, or mentioned shielding. I also noticed that, on mine, the rocker switch is a Tee shape, not the knurled half-round shown in most pictures. I don't know if that was a recent change or not, but mine is flakey (intermittent). Fortunately, the rocker isn't really needed, as the touch screen works well.
The one I received came in 4 days 1st class mail in a small padded envelope, from Virginia. Inside was a clear plastic storage case containing the nanoVNA, two 13-inch sma-sma cables, three sma calibration terminators, a female barrel, and a type-A to type-C USB cable.
To that I added (from other US-based ebay sellers):
-- two SMA male to SO-239 6" RG316 pigtails (my main interest being HF antennas). I would not recommend putting sma-so239 adapters directly on the nano but get short pigtails for flexibility; or get sma female to so239 adapters and use them on the supplied sma cables.
-- three SMA female to PL-259 adapters (so I can use the supplied calibration terminators on the above pigtails; I didn't want to try to locate or build PL-259 terminators).
Both are the DHT Electronics brand, which are very good for hobby-quality pigtails and adapters, being nickel-plated brass with Teflon dielectric. Sold on Amazon under DHT Electronics brand, though they are not listed as "DHT" in many ebay listings, but you can tell they are by the pictures.
The supplied plastic storage case is too small for any extras, so something more practical is needed. See pix; fortunately I ordered a small screwdriver kit a while back and it came with this nice soft case. Ain't that cuuuue?!
73, --kv5r

Hi Tom,

Welcome to the group.

If folks are wondering what to look for in terms of the screening can, it can sometimes be seen in the pictures on some listings (see attached).

Also try and make sure you get battery, S/O/L Calibration kit, back to back SMA connector, USB-C cable and SMA leads included for the price.

Regards,

Martin - G8JNJ

Hi,
Nice packaging.
However, as you use it, you will realize that the 30 to 60cm 50 Ohm cable used for calibration will be calibrated with SMA terminals.
The same piece of cable should be left in for measurement, so you would benefit from using a SMA-SMA cable and an SMA-SO239 or SMA-PL259 adapter. The 30 ... 60 cm cable is SMA male at both ends. When calibrating, need cable and the female- female interleaver will be the Short, Open, Load calibration terminators. The same adapter you need when measuring.

73, Gyula, HA3HZ

Some people reporting that they have measurement issues at low frequency with white "lizard" version.

Also, it seems that Chinese manufacturers prepare firmware to support low quality element by reducing working range of frequencies. So, there is needs to be careful. Cheap NanoVNA may be just a factory rejected boards with a bad quality components and 800 MHz firmware.