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Hi Gary,

I just wanted to make that I answered your question as to why a Short and an Open are not plotted at -1 and +1 after calibration. (The short answer is: because their actual Gammas do not equal -1 and +1.)

As to the math, don't be daunted! It is more straight-forward than you might think. Keep in mind:

1. The basic formula for one-port error correction is based upon the one-port signal-flow graph.
2. Deriving an equation from a signal-flow graph might seem awkward, but there are a number of sites on the web that will give you the rules (if I could do it, I'm sure you can, too).
3. The result will be an equation that, after rearranging, will give you an actual Gamma in terms of a measured gamma and three error terms.
4. But you cannot use this equation to find an actual Gamma until the three error terms are known.
5. To find these error terms, you first make three S11 (Gamma) measurements, each measurement is of a device with a *known* Gamma (thus you need 3 devices of different known Gammas).
6. For each measurement, plug the measured Gamma and the "known" Gamma into the equation derived in step 3, above. This will give you three equations with three unknowns.
7. Solving for the unknowns (i.e. the errors) is linear algebra.

Best regards,

- Jeff, k6jca

I have had bad experiences with N connectors, even of the "precision" type
on high-quality equipment (interconnections between mainframe and S-parameter
test set on HP VNAs, for example). Getting a solid (resonance-free) connection
tends to require wrench tightening of the N connectors. And they are pretty
fragile with respect to mating male connectors of poor accuracy, particularly those
in which the center pin is positioned too far out. This is really too bad because
N connectors otherwise have a great deal good to offer.

My main concerns with SMA revolve around their fragility and their supposed
short life vis-a-vis connect / disconnect cycles. I believe that the SMA-like
3.5mm connectors are better on both counts.

Please, please, do not even think about BNC connectors. They have no place
whatsoever in any measurement application due to poor shield integrity. Also
these days they are being made with such sloppy tolerances that in some cases
mating or unmating requires excessive forces. TNC tend to be better, although
they are sufficiently rare that many people would complain.

My lab VNA (CMT S5048) uses N connectors, and I always use adapters to SMA
with them, in part in their role as "connector savers" so that the connectors on the
VNA see less wear. I feel that this is a reasonable compromise, subject to the
caveat about shield integrity, for which I check each time I do a calibration.

Dana

Because of popular demand we replaced the jog switch with buttons (see attached).
Yes these are through-hole so should be able to take some force.
(Also note the SMA connector on the actual product will be longer than in the picture, in order to accommodate enclosures.)

Hi all,talking of the jog switch,im thinking of fitting buttons to mine,just wondered is the common pin the center leg,looking from the rear ond the top left pin the enter connection?,thanks in advance.

On my nanovna clone the battery was slightly bulged from the factory.

It's mad that the known wouxun fault from 2010 still persists (they put the battery voltage measurement voltage divider BEFORE the power switch. So the 1600mAh battery lasts almost exactly a week in storage with that drain). Baofengs have been a bit hit & miss, one holds charge for months easily, while the other only for a few weeks.

Jeff, Erik, and John;

Thank you all for your patience with me on this. I at least feel comfortable with what I think I understand so far.

Once again I failed to express myself correctly and used the word devices in lieu of system. My bad... It inspired an answer to a question I wasn't asking. :-) I apologize for that and genuinely appreciate your (Jeff) response. That issue aside, I don't have any issues with your explanations, and they remain consistent with my understanding. My problem lies in following the math behind all of this to confirm or enhance my understanding of how calibration accuracy is assured. All signs point to this being done correctly, the results achieved are as desired, and the reasoning is rational. I'm not trying to be or to sound critical here... and at the risk of again inaccurately expressing myself, I'm not looking for cook book summary descriptions. The math is involved and challenging for an ole' timer to follow before losing concentration and falling asleep, and being new at the game of scrutinizing VNA performance to this level of detail makes it all the more daunting. I've resisted trying to figure out signal flow diagrams, but I sense learning how to use them may be less tedious than to continue trying to crawl through the equations and running spreadsheet examples. Learning is one of the perks of retirement though... and its all fun. :-)

Thanks again guys.

--
73

Gary, N3GO

OK well I know that the supplied battery is about 350-400ma and I get about 2.5 hour running time.
That to me says that the battery it good.

So it could be a high leakage / quiescent in the switch controller, or that I'm getting a bit old and forgetting just how
much I may have used my Nano VNA without charging it.

Both a highly possible ;-)

As for shelf life normally.

I have a whole bunch of Li-Ions in use here, 18650's, HT battery packs, spare cell phone packs.

I'd say that I would expect to find a 90% charge from anything from 3-6 months, or even 12 months.

Bit some cells seem to be worse than others, so it's not guaranteed.

The worst case is a spare cell phone battery that holds loses 50% in about 6 months.
These figures assume that I have properly isolated the terminals from the equipment.

Otherwise it is easy to be mislead.

My Wouxun HT's are quite poor in this respect, they would need a good top up charge after a few few weeks if not isolated
due to power switch leakage.

On the other hand, my Baofeng UV5R and others don't seem to give rats ass about storage and easily hold 80% charge for
6 months or more. Not Nano VNA related, but a useful comparison of shelf life.

Sent just for info only...

73 de Andy

Same problem here. I purchased two from eBay seller harborcityelectronics, see item # 121096249091. Repair was straightforward with no issues and I have a spare.

73

-Jim
NU0C



On Mon, 06 Jan 2020 06:39:04 -0800
"slawomir.kleczyk" <ssb@...> wrote:

Hi to all,
a few days I received NanoNVA-F. I bought on Aliexpress. Unfortunately, the rotary switch only worked one way and blocked the functions on the touch screen. I had to undress it but repair is impossible. Does anyone know what type of this switch is and where to buy it? The seller has not yet responded to my complaint.
Happy New Year
Slawomir

On Mon, Jan 6, 2020 at 03:06 PM, Aleksander Shalygin wrote:

For an N connector, the seller must have an adapter option with a calibration
kit.
My counterpart. It is very convenient to work. And the BNC option should be
similar.
It solves many technological problems in production. (Apologies for bad
English from Uncle Gogl.)

It is really a good design. I am trying to improve the performance of the current version of nanoVNA 300-900MHz. I will consider using N-type connectors after completing the related improvements. Will also consider letting edy555 make similar attempts in his next-generation VNA.

hugen

At the beginning I added ip5303 to NanoVNA just for my convenience. But I didn't expect it to be so popular with the community. Now I have realized that this design is not reasonable and has been improved in NanoVNA-H rev3.4.

hugen

On Mon, Jan 6, 2020 at 07:09 PM, hwalker wrote:

On Sun, Jan 5, 2020 at 08:57 PM, <hugen@...> wrote:
English translation with the help of "Microsoft Translate" …..

Hope not too much was lost in translation.

- Herb

Thank you for your translation.

hugen

I finally found a few posts relating to this in the archives, and have to agree there's a problem. Someone had measured about 60?A of leakage when off - try measuring this on your unit and see how far it's off. At 60?A, this should last several months without charging - if it's flat in a month, that battery's not holding a charge as it's supposed to. (The Injoinic datasheet for their IP5303 says typical of 100?A quiescent current draw when off.)

IMHO, the charging system with the IP5303 is very wrong for the typical battery capacity of 0.4 to 0.45 Ah. Thus I'm worried about my battery now as I charge it. The battery, if you have a good cable and the power supply can do it, will be taking in a charge greater than 1C. This stresses the battery and likely will cause premature battery failure in cheap batteries.

The IP5303 is so inflexible that the only thing I can think of doing that doesn't waste charge energy is adding another battery in parallel, which will give enough load to balance out its seemingly inability to reduce charge rate for smaller cells. The IP5303 probably is expecting at least 1.5Ah of capacity or so, and likely less than 3Ah.

The power wasteful but simple solution is adding a resistor into the USB charging path to limit charge current. Maybe 0.33 ohms or so. This should improve the life of the battery pack, both cycle count and hopefully prevent pack failure, at the cost of charging time (and a resistor).

On Mon, Jan 6, 2020 at 01:37 PM, Andy wrote:

" .. I had mine charged, and left it on the shelf for a few weeks and it died on me."
===========================================================
All battery powered devices exhibit some self discharge during storage. My cellphones and tablets when completely powered down require recharging after a few days. A few weeks in my opinion is a pretty good shelf life for a 400 mAh device. Both of my NanoVNA's were delivered via slow boat from China, and were in transit for over 3 weeks. Both retained enough charge to power on when they arrived.

Depending on supplier, some batteries may be better quality than others so its hard to make a blanket statement regarding battery performance from a product like the NanoVNA that has multiple suppliers. I noticed hugen's new version 3.4 pcb has a 650 mAh battery instead of a 400 mAh one. This should translate into longer operating time, at least until the 4" display is added.

- Herb

I've noticed that my second unit's battery is starting to swell a bit. Time to swap it out.?

I think the batteries used on the copies of hugens unit are of low quality and are not lasting? as long as they should.? It might also be the counterfeit ip5303 charge controllers on some units as well...the ones that fail to sense load after a while and you need to add the power-on button to pin 5.?

YMMV



On Mon, 6 Jan 2020 at 4:38 PM, Andy via Groups.Io<punkbiscuit@...> wrote: Has anyone noticed that the shelf life of the Nano VNA seems a bit short ?
I had mine charged, and left it on the shelf for a few weeks and it died on me.
Seems to me to be some sort of high quiescent stand-by state possibly through the switch controller ?

Operating life, when charged and immediately used is good though, indicating the battery capacity as being about 400ma.

73 de Andy

Has anyone noticed that the shelf life of the Nano VNA seems a bit short ?
I had mine charged, and left it on the shelf for a few weeks and it died on me.
Seems to me to be some sort of high quiescent stand-by state possibly through the switch controller ?

Operating life, when charged and immediately used is good though, indicating the battery capacity as being about 400ma.

73 de Andy

Google translate had a slightly different but important statement at the end on availability....

"AA6KL is further improving its development. NanoVNA-H with STM32F303CCT6 and 4-inch display will be launched soon. I hope that the community can have more fans"

Looking forward to seeing them on the market before too long...

Roger

This is the weakest element of this device. It has not worked since the beginning. I have 3 weeks. I need information about the type of this switch and where to buy it. I will order 2 pieces.

had the same issue with mine,the flimsy legs snapped off my jogwheel,managed to dremell away the plastic put 3 blobs of solder on the remains of the legs then sweated it back on the pcb,good idea but a crap quality switch!

That is the screen i fitted to mine,works a treat,quite cheap as well.

i found the jog wheel fine to use,just a badly made piece of crap tho!,would be fine if better made!