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Hi all,
Having some confidence I've completed calibration on the band of interest
to me (I think I did 10MHz to 11MHz), I am getting the same titled scan of
pretty much any number of filters I threw at this (I enclose a sample). I
am not sure if I need to return this, or request a replacement some other
way.
I contacted the seller (R&L), but it doesn't look like they have stock at
all and they haven't had any in a while.
[image: image.png]
Thank you all for you input.
Radu.

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On Wed, May 6, 2020 at 8:23 PM Radu Bogdan Dicher via groups.io <vondicher=
[email protected]> wrote:

I think I figured it, a bit trial and error and such. The idea seems to be
to turn off two traces out of four and make sure the two left follow
certain inputs (LOGMAG for each CH). Past this step, it's a bit weird how
the calibration menu steps one ahead on you, making it a bit confusing as
to whether it completed the previous step or not. But it seems the traces
settle in a way that tells me the device read "itself" and calibrated
accordingly.

I'm repeating the procedure, as my 10.7MHz filters plots still lean lower
on the left side. This is across multiple filters, can't be due to them,
still think it's the device.

On Wed, May 6, 2020 at 7:41 PM Radu Bogdan Dicher via groups.io
<vondicher=
[email protected]> wrote:

I'm at the start of the calibration procedure, and I've connected both
cables on CH0 and CH1, while using the pass-through attachment ("F-F SMA"
in the v1.1 guidelines, in my interpretation) on the other end of the SMA
cable coming from CH0.

The menu steps are clear until step 4, which calls for a "4. SINGLE." I'm
not sure what this is. I don't see it anywhere following/around TRACE 0
(which is there). I wonder if this is due to recent changes in the menu
structure. Or maybe I am just missing something...

Thank you all for your help.
Radu.

On Tue, May 5, 2020 at 7:14 PM Radu Bogdan Dicher via groups.io
<vondicher=
[email protected]> wrote:

Thank you all.

Firstly - on the attachments. Paul: I guess by elimination works great!

;)

In fact, makes complete sense and thank you.

Secondly - on the filters. Jim: yes, I am terminating the measuring rig
properly by impedance matching (closest possible to 330ohm to filters

and

50ohm to the NanoVNA). Even after eliminating unnecessary
complications (50ohm BNC cables, SMA adapters, etc.), the filters

response

is still screwy (though much improved), and this is across multiple
filters. I assume next step on this pursuit is to recalibrate. I assume
this is probably about as good as factory calibration, so there's not

much

to loose there.

Thirdly - on the manuals/files: Thank you for that repository, I wasn't
aware of it!

Radu.

On Tue, May 5, 2020 at 6:37 PM Jim Allyn - N7JA <

jim@...>

wrote:

If the filters are not properly impedance matched, they will not be
symmetrical. In fact, the passband may be horribly distorted

compared

to

what you expect. Further, the group delay of the filter will be

screwy,

which is important to those going for minimum distortion in their FM
receivers.

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I purchased the H4 from Alibaba. I'm very satisfied. It was $70 USD delivered in less than a month.

The vendor was recomended by a microwave group I'm a member of.

?___
Sent from my two way wrist watch
73 de W3AB/GEO?

I am looking for a nanoVNA that will cover 23cms band and has a larger screen that my old eyes can see :-(
At the moment, there are several Ebay sellers offering what appears to be the 4" screen 1.5GHz version of the nanoVNA at a very attractive price? (attached screen grab)
The pictured device claims to be a 4.2 Version (I assume they mean firmware?) so seems pretty current?
However they call it an Antenna Network Analyser rather than VNA.
I am sure I read on this group that when upgrading the firmware there is VNA, and a separate Antenna Analyser firmware.
Also there is a spelling mistake in the on-screen menu :- MARKER is spelled MARKEY leading me to suspect it is a clone?
I would welcome all your experienced advice and advice please :-

1) Has anyone purchased one of these devices recently off Ebay ?
2) Is it running the full VNA firmware ie. Logmag, Phase, Delay, Smith, SWR, etc?
3) Does it have the full input screening?
4) is it a Hugen device or a clone?
5) how well does it work at 1296MHz

Having bought a cheap nanoVNA only to discover is was rated as a BAD clone on this forum (and spent today adding screening cans to 'tame' the input noise), I thought I had better get some advice from you before making the same mistake again.
Thanks in anticipation.....
Dave

I agree with you. My problem was how to modify this ratio into the NanoVNA firmware; thanks to DiSlord, who modified the code with "my" oscillator value and giving to me the modified dfu file,

i was able to upgrade my NanoVNA with this file and get a very acceptable 1 ppm error instead of the previous -85.5 ppm.

Hello Dave,
The screen shots you appended show just a quarter of thr screen.
I think you wanted to append the whole screen size of the nanoVNA.
I thought you have already seen that.
73, Rudi DL5FA

Hi Rudi what did you wish to know?
My nanoVNA was the 'BAD' clone without screening cans over the input stages
and exhibited unwanted vectors due to noise pickup when is Smith Chart mode.
Since adding the cans the noise is cured :-)
Dave

That's the method HP uses in a lot of their gear. They use a very stable TCXO and to calibrate the frequency you change the divide by ratio. On my 8920 to calibrate the frequency you input a 10MHz frequency from a standard (GPS or whatever) and it compares the 2 and then changes the divide by on the internal oscillator (which doesn't run at 10 MHz) to match the reference. Very easy this way, no tweaking.

Why not ?

As i want to replace my oscillator in the future, a good idea

to reverse to a new value !

Thank you one more time and all the best.

Rudi

Good, possibly in future i add command for allow user set this correction.

Hello Dave,
Your screen shots does *not* tell the whole story.
72, Rudi DL5FA

BINGO !

After upgrading with your DFU file, i enter 100MHz in "CW" mode and

get 100.00010 MHz at the GPS locked frequency meter.

1 ppm instead of the initial -85.5 ppm !

Fine Job DiSlord and many thanks for your help and DFU file !

Best regards,

Rudi

I suggest you launch a kit for those who bought and did not have a small display.
Case + display module 4 inches + firmware.

Select target id
00 Internal Flash 64 sectors or

And press Upload

Then you upload file from NanoVNA programm read all flash 128kB and save to file
Then formware created, not used space not stored to file. 82kB correct file size

Yes it Ok

After reading the option "01", seems that you dfu file should be written into target option "00" (internal flash 64 sectors).

A 2nd point: NanoVNA v0.8.4.6 Xtail 25997748.dfu is 82 Ko but the uploaded file from my NanoVNA is 129 Ko , is this ok ?

Rudi

Hi DiSlord,

I installed DfuSe, connected to the NanoVNA after "Reset and enter DFU" activated;

on the DfuSe screen i have 2 Targets options:

-1- 00 Internal Flash 64 sectors or

-2- 01 Option Bytes??? 1 sector.

What is the correct target ?

Thank you for your help.

Rudi

A new technical support page for the NanoVNA-V2 is available at . I believe Gabriel posted here, or elsewhere, that the NanoRFE Foundation will be taking over the production of the V2. There is an "about us" page that gives details about the NanoRFE Foundation.

- Herb

Ed,

*1)* You've got a typo in your callsign: it should be KC1D*YK* (ROKBL!)

*2)* In terms of verifying the fundamental measuring impedance of the nanoVNA, that's a lot trickier. The essence of most VNAs is that the VNA is approximately correct, but to take an accurate measurement the VNA is compared to a set of reference impedances (the SOL calibration). [The nanoVNA S_11 bridge can be seen in the circuit diagram (schematic) for whichever model of nanoVNA you are using.]

*3)* Given that you are an M.Math, but I a mere subverter of otherwise pristine mathematics towards practical application (also known as Engineer), then you can probably imagine the system of matrices which make this more-or-less work.

*4)* On a very practical note, the cost of a good calibration set can, for good reason, easily exceed the cost of the VNA itself, since nanoVNAs are so very cheap, but accuracy is demanding.

*5)* I admire your experimenter's attitude of "Let's just measure it", which the nanoVNA readily allows one to do. The discrepancy that you've measured is one which, a few years ago, would simply have passed unnoticed, without access either to very expensive test gear, or to cheaper test gear that requires a slow manual process that few would undertake as a matter of course!

*6)* There is also the question of the impedance of CH1, for S_21 measurements, but that's a rabbit hole for another day.

*7)* In short, the measurements that one gets from the nanoVNA are only as good as the calibration references in use. Or if one prefers, the numerical results from a VNA directly come from the calibration set used for those measurements. The numbers *are* the calibration. [That's the essence of it.]

HTH, 73, Stay Safe,

Robin, G8DQX

Hi just spent a UK windy afternoon confined to my radio 'shack' , so decided to upgrade the screening on my 'basic' clone nanoVNA to see if the INPUT 'noise' could be reduced.
I made the screens out of some 'shim' brass foil and formed them round some srbp (Tufnol) formers THAT I made first.
I am pleased with the improvement that just a couple of hours 'metal bashing' has produced.
Hopefully this will inspire others to have a go?
Dave

Thank you very much DiSlord for your help and work.

I will install this file this afternoon and inform you for the result.

Regards,

Rudi