开云体育

I use Ansmann cells in my other projects.

Can sustain 2C charge + has battery management included.
At worst case in a Nanovna, don't charge via USB, but via your own preferred external charger ?

- Andy-

I noticed on my unit the larger font is clipped at the bottom of the screen and at the top right.
Is there a way to change this?

Sam
W3OHM

I got one also, as time passed I thought it wasn't coming but it just took 2 months. I ordered something else that came much quicker and I noticed on the tracking that it seems like it's the time of the month maybe. Like I missed the boat on the first order so to speak.?



On Sat, Nov 23, 2019 at 11:42 AM, eyelessmisfit<eyelessmisfit@...> wrote: FYI, bought one of the 'deal's ($21), from ebay. Got a tracking number and was told it had been shipped. Never arrived so i contacted the seller and got no reply. Ebay got involved when i contacted the seller, gave them 5 days to make good and when they did not, ebay gave me a full refund!EBay makes your purchase no risk, so go ahead and take a chance. Sometimes you get a good one.Ron

Hi Norbert
If I understand you correctly you calibrated the Ch0 port directly and then just connected the various cables to Ch0 port and terminated at the far end with a female 50 ohm load.
If so it is only a measurement of how well the various cable can "transport" the 50 ohm load to the Ch0 port and obviously there is various impedance transformation pending the quality and characteristic of the different cables. It has nothing to do with impact on calibration.
If you had calibrated at the end of the various test cables then you should see no difference but for the NanoVNA you will because is has no build in error corrections, it just relies on the performance of the measurement bridge.
The purpose of error correction is to compensate for the imperfection of the output impedance of the Ch0 port and the input impedance of Ch1 port, as you see for you test 5, which is the Ch1 port input impedance transmitted thru the test cable incl impedance transformation caused by that cable.
A golden rule is: Consider always a test cable as part of the equipment - the NanoVNA - when calibration at the end of the test cables and the purpose of the calibration process is to remote the influence of these test cables now being part of the calibration data saved in the NanoVNA/NanoVNA-saver. However for the NanoVNA there is till a small or large impact from the test cables as no internal error 6 term error correction (12 term error correction not possible as requires measurements of all 4 S parameter in one go. So second golden rule use high quality test cable and as short as possible
Sorry .. my contribution tends to be long and is actually missing info on how to calibrate correctly so S11 and S21 phase are in sync and the calibration is done at the SMA male adaptros reference plane and the FF adaptor phase delay also is removed in the calibration process
Kind regards
Kurt

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af Norbert Kohns
Sendt: 23. november 2019 14:46
Til: [email protected]
Emne: [nanovna-users] Coax cable length influence on calibration

Hi all,
today I performed a NanoVNA calibration test to find out if the coax cable length and quality has any negative influence specially on the S11 return loss.

The calibration setup is 10kHz-900MHz at 808 points.
For the test I used high quality coax cable (M17/152) and standard coax cable (RG174U).
The reference test was done directly on the NanoVNA port connectors. For the thru test a 5 cm long semi rigid coax cable was used (picture 1).
Next, a 20 cm long M17/152 coax cable was tested (picture 2).
Then, a 93 cm long M17/152 coax cable was tested (picture 3).
And last, a 70 cm long RG174U coax cable was tested (picture 4).
Picture 5 shows the test result for the RG174U coax cable for S21.

All test conditions have been repeated. The differences between the two tests were negligibly.

One can see, that the coax cable length has some negative impact on S11, specially with the 20 cm long coax cable.
The quality of the coax cable plays obviously a minor roll.

Do the experts among us have an explanation why this is as such?

Best regards
Norbert, DG1KPN

How have you terminated the coaxial cable length under test? Just
measuring S11, I would not recommend using Port 02 as a termination, but,
rather, the 50-ohm SMA cal standard. The impedance of Port 02 over
frequency is not necessarily known. It might also be instructive to
include an open and short test of the cable under test. Certainly, the
'174 should show additional loss over the 'good' cable lengths.

Just another thought: Above 300 MHz, the noise is very noticeable
greater. This shows especially in the tests other than the cal setup,
picture "0". The FW within the NanoVNA may not have the dynamic range to
pull out good data for your tests. An open test is especially good at
detecting loss.

The position of the peaks and valleys is only a reflection of differing
lengths of cable and, therefore, phase differences as measured against the
cal. standard.

Dave - W?LEV

On Sat, Nov 23, 2019 at 1:46 PM Norbert Kohns <norbert.kohns@...>
wrote:

Hi all,
today I performed a NanoVNA calibration test to find out if the coax cable
length and quality has any negative influence specially on the S11 return
loss.

The calibration setup is 10kHz-900MHz at 808 points.
For the test I used high quality coax cable (M17/152) and standard coax
cable (RG174U).
The reference test was done directly on the NanoVNA port connectors. For
the thru test a 5 cm long semi rigid coax cable was used (picture 1).
Next, a 20 cm long M17/152 coax cable was tested (picture 2).
Then, a 93 cm long M17/152 coax cable was tested (picture 3).
And last, a 70 cm long RG174U coax cable was tested (picture 4).
Picture 5 shows the test result for the RG174U coax cable for S21.

All test conditions have been repeated. The differences between the two
tests were negligibly.

One can see, that the coax cable length has some negative impact on S11,
specially with the 20 cm long coax cable.
The quality of the coax cable plays obviously a minor roll.

Do the experts among us have an explanation why this is as such?

Best regards
Norbert, DG1KPN

--

*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*

Hi Andy

On Wed, Nov 20, 2019 at 06:37 PM, Andy wrote:

OK I started testing the charging current on my NVNA.

Typically 650ma on an empty 400ma supplied cell, oh dear !!!

That's 1.625C. Exceeds spec of 1C max. Bad mojo.

Please try charging from a USB2 standard port and measure the current.

I wasn't expecting that to be honest, I really did assume that there would be
some controller regulating the current.

Something is limiting the current given that you were using a 2.1A mains adapter.

My guess it is the battery protection module in the battery itself. Search for DW01-P One Cell Lithium-ion/Polymer Battery Protection IC.

I consider that the IP5303 datasheet to be a bit misleading in my opinion.

It is certainly hard to understand what the charge current will be in practice.

Before I did the test, I also measure the current on a supposedly charged
cell, and it wasn't actually any different.

My guess is that the battery voltage never reached 4.1V so the IP5303 just kept going..

Guess I'll be modding mine for an 18650 cell shortly.

Not convinced this is the best option now. An 18650 would require an external battery protection module.

I've been doing some tests using an old cell phone battery. It is a NEC MAS-BD0021-A001 1100mAh Li-Ion. Must be at least 15 years old.

From a full charge it will run the nvna for 4 hours before the over discharge protection kicks in.

A full charge using a 1A mains adapter takes 3 hours and the charge current never exceeds 400mA i.e. 0.37C.

On a USB2 standard port the charge current never exceeds 200mA i.e. 0.18C.

Cannot find a spec for this particular battery but that looks good to me.

Note that supplied SD 602040 is a Li-Po; the NEC is a Li-Ion battery.

The different discharge characteristics may need mods to the discharge table in the firmware. I haven't looked at that yet.

73
Nick

I tend to be annoyed

Content is available by web searches including site:groups.io/g/nanovna-users

developers can get back to work

That work includes compiling requirements, including input from subscribers

FYI, bought one of the 'deal's ($21), from ebay. Got a tracking number and was told it had been shipped. Never arrived so i contacted the seller and got no reply. Ebay got involved when i contacted the seller, gave them 5 days to make good and when they did not, ebay gave me a full refund!EBay makes your purchase no risk, so go ahead and take a chance. Sometimes you get a good one.Ron

I would suggest that with the NanoVNA being already such a low price, there
is a cost to one's time and effort to engage questionable vendors or
potentially faulty or misrepresented products. While I think that there is
definitely a benefit to the low price, the interest it seems to be based
largely on the price appears with relatively little concern as to the
quality or performance. I think ultimately many hams that are new to the
idea of the VNA will dismiss it as uninteresting junk if it is perceived as
simply being cheaper.

On Sat, Nov 23, 2019 at 10:41 AM Gary Rogerson via Groups.Io <gary.rogerson=
[email protected]> wrote:

Hope it’s not old news, but I just ordered one at Walmart.com for ~$38.

My opinion aligns more with David. The basic question is if this is a product support group or a private group for developers or otherwise includes proprietary information. If this forum is only for developers or is likely to include proprietary info, then it makes sense that the archives are private. But if the purpose of the forum is to provide product support to users, then it makes more sense that the archives are open. Last I heard the NanoVNA was an Open Source project so there should be no proprietary info?

Personally, I tend to be annoyed when I have to join a group in order to research the answer to a simple problem, or even a complex one. When I have joined a group, I get even more annoyed when I see half the postings are asking for answers to the same problems that were answered multiple times in recent weeks. If the message archives are open and searchable, at least some of the questions will be answered before they ask the group AGAIN.

I consider the best reason for an open support group is that eventually there will be enough expert users that newbie questions can be answered by them and the developers can get back to work on the next version or product upgrade. But this is just my opinion.

73, Doug Reed, N0NAS.

Hope it’s not old news, but I just ordered one at Walmart.com for ~$38.

go to walmart .com you get it there for a couple bucks more 3 day delivery and ou know you haven't been scammed. But also, read the fine print because you only get bare bones, no cables, no calibration standard and no shielding. All things that would not deter me because I have them and can shield the unit easy but are not preferable by most people.

Dave, excellent information. I have 3000+ purchases on eBay. Lots of items from China. I always do as you suggest, check the Seller's Feedback and number of sales.

Just one last thought...… Recently, I purchased an 'F' model from a store in China. It was the 'usual' price, around $140. Excellent Feedback (99.3%) on 20,000+ sales. MY problem was: I ordered it on the last day of September. I was told by the Seller that the entire country goes on 'holiday' the first week of October, including all shipping, etc.
Sure enough, weeks went by with no updates on the Tracking Number. I contacted the Seller and he told me he couldn't track it either.
I was given a refund very quickly and ordered another 'F' from another Seller, for the same price. It showed up within the expected time.

ron
N4UE

For those that want to experiment with a nice tool to add/remove transmission/coax line impact there is this very advance excel tool



It requires excel from Office 97 or newer and macro's enabled.

It includes a large database of transmission/coax models and (like simSmith) can read all the VNA output files.

This tool could be some inspiration for nanoVNA-Saver :-)

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

Hi all,
today I performed a NanoVNA calibration test to find out if the coax cable length and quality has any negative influence specially on the S11 return loss.

The calibration setup is 10kHz-900MHz at 808 points.
For the test I used high quality coax cable (M17/152) and standard coax cable (RG174U).
The reference test was done directly on the NanoVNA port connectors. For the thru test a 5 cm long semi rigid coax cable was used (picture 1).
Next, a 20 cm long M17/152 coax cable was tested (picture 2).
Then, a 93 cm long M17/152 coax cable was tested (picture 3).
And last, a 70 cm long RG174U coax cable was tested (picture 4).
Picture 5 shows the test result for the RG174U coax cable for S21.

All test conditions have been repeated. The differences between the two tests were negligibly.

One can see, that the coax cable length has some negative impact on S11, specially with the 20 cm long coax cable.
The quality of the coax cable plays obviously a minor roll.

Do the experts among us have an explanation why this is as such?

Best regards
Norbert, DG1KPN

Simulated port extension methods,:

1. 1 - 500Mhz sweep shorted RG-58C/U (Belden 8262)
2. subtract ideal coaxial line
3. subtract datasheet loss data coaxial line
4. subtract datasheet loss data coaxial line (zoom)
5. subtract advanced model RG-58C/U (Belden 8262) coaxial line (zoom)

Of course, this is simulation only. But you can try load real measurements (s1p) format.



I not a Nanovna or external program developer.

As this ("deal on ebay") has been a recurring theme for some time (these sorts of offers happen on other items, nanovna is one of the subject items for this sort of spam/scam), I would like to suggest the following:

The majority of these non-delivery "deals" arise from misuse of an existing ebay account. If you purchase from one of these listings, you can (and very much should) seek a refund from ebay after the delivery time passes with no delivery.

Almost all of these listings share common characteristics - abnormal buy-it-now pricing (<USD 25), few seller feedbacks (<100, sometimes very few with private or hidden details), no other related items listed (i.e., other items that don't seem to be rf electronics), and no evidence of feedback for sale/delivery of the nanovna. Be sure you're looking at a listing for the nanovna proper (there are numerous multi-item listings that show a price range and might initially look faulty but are not necessarily so.)

Any ebay user can click "report item" link (navigation for US version users is this, other languages may vary --- right side, part way down the screen to the right of "shipping and payments", you may need to scroll down to find it, as it's a simple text link and not very easy to see). Click on "report item" (then you may need to re-supply your ebay password), then choose report category = "listing practices", then choose from reason for report = "fraudulent listing activities", then choose from detailed description = "you suspect that a listing is fraudulent". Finally, click submit report. ebay usually will remove these listings sooner than might otherwise be the case. Doing this properly may help reduce the preponderance of these dead-end listings.

Thank you for your interest in and support of nanovna-users,

Dave

A firmware upgrade for the NanoVNA was just announced by edy555:

"Just released ,NanoVNA firmware 0.5.1 , add marker function 'group delay to electrical delay"

Hard to translate the Japanese description, but I believe it allows the electrical delay values to be changed by dragging the marker - in addition to using the onscreen keyboard.

- Herb

Of course. Port extension not ideal. Simplest method only compensated the electrical lenght. More advenced method use simple frequency depend loss model. Best the complex model.



With nanovna + zplots possibly caracterize unkown coax parameters.

Hi David,

Maybe because members of the group have disclosed the information to the group - if you are interested, you have to log in. This is the case elsewhere.
The -F group is another group, if you have a problem with them, ask for another group.

Regards, Gyula HA3HZ