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I read -70 dB also on two different NanoVnas. Ch0 LogMag @ 50 KHz using the 50 Ohm load that came with the NanoVna. This is the same 50 Ohm that was used in the calibration. The calibration procedure assumes the load to be perfect so return loss shows -70 dB. It goes up with Frequency but is always better than -50 dB. I agree it should be a positive number but the NanoVna displays it as negative.

Jim K.

I responded to this 70 dB return as I was really interested in how he measured this. Reason!!!

There is a lesson to learn here... There is an uncertainty level associated with VNA architectures and I believe you are well beyond that boundary with a measurement of 70 dB. That said...

HOW WAS THIS MEASURED SO WE CAN ALL UNDERSTAND HOW WE GOT INTO FANTASY LAND!

________________________________
From: [email protected] <[email protected]> on behalf of Dr. David Kirkby from Kirkby Microwave Ltd <drkirkby@...>
Sent: Sunday, August 4, 2019 3:28 PM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] NanoVNA Under The Covers

On Sun, 4 Aug 2019 at 08:46, tuckvk3cca <tuckvk3cca@...> wrote:

Thanks Gary. I contacted my supplier, EBay and ask if I could get another
set of cal8bration loads. No luck. The 50 ohm was of very high quality,
return loss -70dB compared to -40dB from another source I had, up to 1GHz.
Anyone knows where to get such loads? Sent from my Samsung Galaxy
smartphone.

Return loss of loads should not stated as a *positive* number as it’s a
loss. A return loss with a negative number could only be obtained from a
negative resistance, such as a Gunn diode amplifier.

A return loss of 70 dB can only found in fairyland! I measured 44 dB, but
stated that the measurement would be subject to large errors as the return
loss of the loads in my 85052B calibration kit were specified as 48 dB.
Really, 70 dB can only be found in fairyland. Another VNA might indicate 70
dB, but the result is meaningless.

Dave G8WRB
--
Dr. David Kirkby,

On Sun, 4 Aug 2019 at 08:46, tuckvk3cca <tuckvk3cca@...> wrote:

Thanks Gary. I contacted my supplier, EBay and ask if I could get another
set of cal8bration loads. No luck. The 50 ohm was of very high quality,
return loss -70dB compared to -40dB from another source I had, up to 1GHz.
Anyone knows where to get such loads? Sent from my Samsung Galaxy
smartphone.

Return loss of loads should not stated as a *positive* number as it’s a
loss. A return loss with a negative number could only be obtained from a
negative resistance, such as a Gunn diode amplifier.

A return loss of 70 dB can only found in fairyland! I measured 44 dB, but
stated that the measurement would be subject to large errors as the return
loss of the loads in my 85052B calibration kit were specified as 48 dB.
Really, 70 dB can only be found in fairyland. Another VNA might indicate 70
dB, but the result is meaningless.

Dave G8WRB
--
Dr. David Kirkby,

Good day. I am curious how did you measure a 70 dB return loss? That is an extraordinary measurement indeed, Thanks.

________________________________
From: [email protected] <[email protected]> on behalf of tuckvk3cca <tuckvk3cca@...>
Sent: Sunday, August 4, 2019 7:46 AM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] NanoVNA Under The Covers

Thanks Gary. I contacted my supplier, EBay and ask if I could get another set of cal8bration loads. No luck. The 50 ohm was of very high quality, return loss -70dB compared to -40dB from another source I had, up to 1GHz. Anyone knows where to get such loads? Sent from my Samsung Galaxy smartphone.
-------- Original message --------From: Gary O'Neil <n3go@...> Date: 04/08/2019 08:55 (GMT+01:00) To: [email protected] Subject: [nanovna-users] NanoVNA Under The Covers Having expressed accolades to AliExpress supplier Guangyi0016 store... I felt duty bound to provide a thorough overview of the hardware itself. I also think I missed the "i" in the supplier's ID, so I corrected it here. :-)If the attached photos are of insufficient resolution, I can attempt uploading them at higher definition. I first removed the top and bottom covers and observed that both are constructed of double sided copper clad PCB material (appear to be FR4), and both are painted on both surfaces. The external surface of each are both stenciled, but don't appear to have a clearcoat finish to protect them from wear. Users might want to remove and spray them with a clear acrylic for added longevity. I then photographed both sides of the board and made the following observations:1. The front-end shielding provided is mounted in blade standoffs, such that they can be readily removed if repairs are warranted. I removed them forthwith and photographed that side of the board again for completeness.2. It is unclear whether or not a footprint exists for an SD card reader, but I don't believe there is. The internal LIPO battery pack is secured in place with double sided tape, where such a footprint would likely reside. 3. There is not an on-board LIPO charger, but rather a tiny sliver of a PCB is afixed (presumably taped) to one end of the LIPO battery and wrapped in Kapton. 4. Brass standoffs are used to suspend the covers above and below the board. The paint on the covers prevent them from serving as a ground references, so the covers only serve to provide electrostatic shielding. 5. The mixers are SA602's, the processor an STM32F072CBT6, The codec an AIC3204, and the clock an SI5351. It looks to be a pretty faithful clone. 6. The PCB is stenciled, and marked under the battery as "NANOVNA V3.1".I secured the shields back into position, reattached the covers, and verified all was well.I performed a couple of 1 port calibrations, plugged it into my Windows 10 machine and verified that it communicates with the NanoVNA Sharp GUI. From there I was able to download the attached Firmware info.Navigating the hardware is pretty intuitive. The NanoSharp GUI not so much. :-) I'll stop here before I accidentally delete everything I've composed here again... Yikes! Fortunately it was autosaved as a draft. Phew! For the first few hours out of the box an all in all very positive experience. 72/73Gary, N3GO

Hello Gary, and other users of the Group,



I would like to correct your comments regarding the 2 outer Covers of the nanoVNA, being only an electrostatic shield at best because they are not at ground potential. My unit is identical to the one you show in your photographs.



The Covers are both indeed grounded. The 4 mounting holes in each cover is a plated through hole, and there is a small area of no paint around the rim of each hole. The screws, when tightened down properly, do indeed ground to the little brass stand-offs mounted on the main board, and thus the PC copper material on the face and the reverse of the 2 shield covers are properly at earth potential. I have also made certain of this by measuring each plated thru hole to ground with an Ohmmeter which says 0? in all 8 cases (with the other 7 screws in place).



73’蝉

Peter, ZL2iK

Another possible alternative would be to 'shim' the interface. It would be possible to have a userspace driver that translated from NanoVNA to (say) MiniVNA, assuming that they operated in some arbitrarily similar way. The NanoVNA seems to take basic setup commands to configure a sweep, and then read back a buffer of values to plot whatever curve is required. If other VNAs behaved similarly it would be possible to do this.
Another possibility might be to just start from scratch. There is a bit of basic code in Python, so I am going to look at this first I think,
/ Gerry

I have some boards for the 'Yet Another VNA Project' if anyone is interested in doing a bit of soldering.
They are SMD boards not TH.
/ Gerry

I want to add my experience to this. I also purchased from Guangy0016 and received what is considered to be the 'best clone', i.e. black, with shielding + ch0 legend, USB C. I have compared performance in reflection & transmission to a known good MiniVNA Tiny, and found them almost identical when measuring 2m & 70cm antenna and a 40m BPF.
I am very satisfied with my purchase.
73
Gerry

Excellent review, Gary.
The small PCB on the battery is the protection circuit. The charging circuit is located just below the jog switch and is a combined LiIon charger and 5v inverter.
Lastly, this version of the PCB removed the SD card pads so going forward, there is no longer an incentive to add local storage routines to the firmware.
Cheers,
Larry

Thanks Gary. I contacted my supplier, EBay and ask if I could get another set of cal8bration loads.? No luck. The 50 ohm was of very high quality, return loss -70dB compared to -40dB from another source I had, up to 1GHz.? Anyone knows where to get such loads??Sent from my Samsung Galaxy smartphone.

Having expressed accolades to AliExpress supplier Guangyi0016 store... I felt duty bound to provide a thorough overview of the hardware itself. I also think I missed the "i" in the supplier's ID, so I corrected it here. :-)

If the attached photos are of insufficient resolution, I can attempt uploading them at higher definition.

I first removed the top and bottom covers and observed that both are constructed of double sided copper clad PCB material (appear to be FR4), and both are painted on both surfaces. The external surface of each are both stenciled, but don't appear to have a clearcoat finish to protect them from wear. Users might want to remove and spray them with a clear acrylic for added longevity.

I then photographed both sides of the board and made the following observations:

1. The front-end shielding provided is mounted in blade standoffs, such that they can be readily removed if repairs are warranted. I removed them forthwith and photographed that side of the board again for completeness.
2. It is unclear whether or not a footprint exists for an SD card reader, but I don't believe there is. The internal LIPO battery pack is secured in place with double sided tape, where such a footprint would likely reside.
3. There is not an on-board LIPO charger, but rather a tiny sliver of a PCB is afixed (presumably taped) to one end of the LIPO battery and wrapped in Kapton.
4. Brass standoffs are used to suspend the covers above and below the board. The paint on the covers prevent them from serving as a ground references, so the covers only serve to provide electrostatic shielding.
5. The mixers are SA602's, the processor an STM32F072CBT6, The codec an AIC3204, and the clock an SI5351. It looks to be a pretty faithful clone.
6. The PCB is stenciled, and marked under the battery as "NANOVNA V3.1".

I secured the shields back into position, reattached the covers, and verified all was well.

I performed a couple of 1 port calibrations, plugged it into my Windows 10 machine and verified that it communicates with the NanoVNA Sharp GUI. From there I was able to download the attached Firmware info.

Navigating the hardware is pretty intuitive. The NanoSharp GUI not so much. :-)

I'll stop here before I accidentally delete everything I've composed here again... Yikes! Fortunately it was autosaved as a draft. Phew! For the first few hours out of the box an all in all very positive experience.

72/73

Gary, N3GO

I received my NanoVNA today... just 22 days after ordering it. FWIW, I made the purchase via the AliExpress App, and the supplier was the same as used by at least two others with similar delivery reports (~ 3 weeks).

Several points are probably worth noting.

The supplier I used was Guangy0016 store, and his current asking price is $46.99.

I have used AliExpress in the past, and have had no issues to date. By that I mean that the goods received were of anticipated quality, price and delivery. As such I've had no opportunity to test AliExpress's make good policy.
I do use the AliExpress app, which I just learned has a reassuring feature that presumably holds their suppliers accountable . It requests that you report back when you receive the goods and have no issues. You pay for the goods through AliExpress, and they hold back payment to the supplier for 60 days, allowing you time to register a dispute. It serves as an incentive for the supplier to close the deal, and have the goods in your hands before the 60 days are about to expire and you file a dispute for late or no delivery.

My choice of this supplier was the consequence of my own research, and no a reaction to two successful purchases reported on this forum... which I learned of after placing my order. This is only relevant in the context of how I narrowed my search to this supplier.

1. He is an AliExpress supplier.
2. His price was competitive an at the price point I was targeting.
3. He referenced online documentation that appeared to be most up to date, provided links to the best English language repository of manuals, and firmware versions, and a zipped NanoVNA Sharp file, I was able to identify.
4. The NanoVNA came complete with battery, accessories (SOLT Cal kit and cables) and a carrying case roughly the same size as my iPhone X. :-)

Tracking was provided,.. complete with alert updates as it made it's way through China Post and USPS. I was also quite pleased with the way it was packaged, and exceptionally well protected (photos attached).

So... until somebody experiences a legitimate concern with AliExpress or gets burned by Guangy0016 store, I think this source for the NanoVNA is worthy of being added to the satisfactory suppliers list.

--
73

Gary, N3GO

Thanks for the info - useful to know. I had to laugh when I read this
though:

"About Us

1.We are professional factory to make kinds of motorcycle CNC
accessory,such as kinds of modified brake clutch levers,rearsets,foot
pegs,steering dampers,kickstand sidestand,handlebar clamp,swingarm spool
bolts and so on."

Predumably it means they must have at least one engineer on the premises,
even if the wrong type. The Ebay seller I bought from seems to specialise
in mobile (cellular) phone cases.

Regards

Mike





On Sat, 3 Aug 2019, 16:48 Dr. David Kirkby from Kirkby Microwave Ltd, <
drkirkby@...> wrote:

I see lots of people having trouble sourceing what they consider a good
version. I bought his one



I can't really complain

* It came with a battery
* It has 4 traces
* It has screening
* It works to 900 MHz with no need to mess about with the firmware.
* There is no evidence of spurious signals.

Downsides
* The build quality is poor - but that seems to be the case was all of
them. I've yet to see any reports of good build quality.
* No mention of where to get the GPL source code.
* The "open" supplied is worst than just leaving the connector open, as the
added capacitance just makes the "open" less like an ideal open. That is
going to tbe the same for any "open" unless you go to great lengths to stop
it.
* Although the load has an excellent return loss, there is a problem with
it which I overlooked the first time I posted about that.

The first did not work (bad display, which Hugen said is delicate), but
they sent another which is okay. I asked them to send that express mail,
which they did, but it had to be without the battery. So I had to swap that
over. I can't really complain, and its probably a lot safer than buying
from Alibaba, or some obscure Chinese website.

--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100

I see lots of people having trouble sourceing what they consider a good
version. I bought his one



I can't really complain

* It came with a battery
* It has 4 traces
* It has screening
* It works to 900 MHz with no need to mess about with the firmware.
* There is no evidence of spurious signals.

Downsides
* The build quality is poor - but that seems to be the case was all of
them. I've yet to see any reports of good build quality.
* No mention of where to get the GPL source code.
* The "open" supplied is worst than just leaving the connector open, as the
added capacitance just makes the "open" less like an ideal open. That is
going to tbe the same for any "open" unless you go to great lengths to stop
it.
* Although the load has an excellent return loss, there is a problem with
it which I overlooked the first time I posted about that.

The first did not work (bad display, which Hugen said is delicate), but
they sent another which is okay. I asked them to send that express mail,
which they did, but it had to be without the battery. So I had to swap that
over. I can't really complain, and its probably a lot safer than buying
from Alibaba, or some obscure Chinese website.

--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100

Hi hugen,

Thanks for the link. I prefer ebay, but I try thisuser.

Regards, Colin.

Having a central repository for files and possibly links is way better than
telling people to search all posts for "something discussing what I think
was screws" but which actually referenced "bolts".

Such a file repository should be structured in some sort of way, if it
grows beyond a dozen files or so.

Den l?r 3 aug. 2019 02:42Larry Rothman <ac293@...> skrev:

Thanks, I'll have a look.
I want to be careful not to increase the 'noise' with a pile of links but at the same time, search for and post some really useful ones, IMHO.

73
Larry VE3LRI

On Fri, 2 Aug 2019 at 10:20, Larry Rothman <ac293@...> wrote:

I like to research all my projects and have found a number of software and hardware resources of the NanoVNA, EU1KY VNA,and DG8SAQ VNA that users and/or developers may find useful.
(MOD: Feel free to relocate this to the WIKI area)

I took the liberty of creating a page for external links.
I don't have my nanoVNA yet, so I don't have anything to add to...
well, to any discussion except this:

The idea of a wiki is that anyone can edit it, and everyone should.

The wiki for groups.io is very primitive, which means it's really easy to use.
For this page, all I did was copy Larry's message and paste it into a New Page.
I then edited the home page of the wiki to have a link to this new one.
I left the boilerplate for the home page intact, in case someone wants
to start work on it.

It's not that pretty, but the search works fine.

/g/nanovna-users/wiki/home

73 de buck, kc2hiz

The NanoVNA USB port was originally designed as a debug interface, according to the original designer (edy555).
Since he open-sourced the code, maybe others will add additional functionality.
The only issue here is how much memory is left over on the uP for adding options.

I like to research all my projects and have found a number of software and hardware resources of the NanoVNA, EU1KY VNA,and DG8SAQ VNA that users and/or developers may find useful.
(MOD: Feel free to relocate this to the WIKI area)

Yet Another VNA Project:
- uses the NanoVNA H/W & S/W design in part and references his github firmware resource.

SimSmith & tutorial:
- Referenced by the Yet Another VNA link above.

Zplots - Impedance Plots using Excel Charts:
- Use this to model your designs.
- I wonder if it could be modified to accept input directly from the NanoVNA?

DXzone VNA reference page:
- An excellent Amateur Radio website with numerous technical reference links.

Building an S-Parameter Test Set for the VNWA-3E:
- An easily built S-Parameter Test Set - possibly useful for the NanoVNA

Cheap homemade 30 MHz - 6 GHz vector network analyzer :
- Refer to building and using the Calibration adapters close to the end of the article.