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Hello Dave,

I agree to your statement, if the RF Test Kit is used for an university course.

73, Rudi DL5FA

On Wed, 8 Jan 2020 at 21:45, n5kzw <n5kzw@...> wrote:

That tool looks like it would take all of 5 minutes to make. - Ed

Yes, but it does not solve the problem that a completely inappropriate
connector is used.

I also ordered from Alibaba via a message on hugens store, and paid via Paypal on 12/30/19. I received today 1/8/20 via DHL. Well packaged, VERY nice unit (much better than the junk one I received from fleabay!), with the new PCB and software. Goes to 1.5g. Of course the package had 2 shorts, 1 load and no open for the calibration parts, but I can live with that since I already have an open I can use.

I'm no expert. but it's very clear right out of the box this unit is much better than the previous unit I got (which was the no "ch0" text on the front unit). Off to read/learn me up on this thing. ;-)

--
Regards,
Chris

On Wed, Jan 8, 2020 at 11:33 AM, <entilleser@...> wrote:

I have a relatively new ASUS Chromebook, with the latest Chrome version, and the experimental-web-platform-features enabled. The Web Client is working for me.
==================================================================

The issue with Chromebooks has been that with the latest Chrome update you can connect the NanoVNA with the web based application, but not off-line using the Google Play Store android application. If you are able to connect off-line using the android application then your ASUS Chromebook would be the first reported to do so.

- Herb

That tool looks like it would take all of 5 minutes to make. - Ed

I have a relatively new ASUS Chromebook, with the latest Chrome version, and the experimental-web-platform-features enabled. The Web Client is working for me.

Hi,
For clarification: An SI5351 outputs square-wave signals that contain only odd multiples of the fundamental frequency (3 * f, 5 * f, ...).
To reach 1500 MHz, 7 * 214.285 MHz are therefore required as fundamental frequency.
In the analyzer according to EU1KY, however, we did not go beyond 5 times, and I reached e.g. 1450 MHz with 5 * 290 MHz. Prerequisite was a test of the maximum possible frequency of the SI3531 circuit.
Wolfgang, DH1AKF

Hi

SiLabs datasheets are so and so when it comes to clarity. The current datasheet says that Si5351A can go up to 200 MHz. However, the max VCO frequency is 900 MHz, and with the then "forced" divider ratio of 4 this results in a max output frequency of 225 MHz. Is this within or outside of the spec? Not really sure - one could argue that the 4 divider cannot work properly above 200 MHz, but it does. However, many VCOs can go close to 1200 MHz from where the 300 MHz comes from, i.e. 1200 MHz / 4, but, again way out of spec., and not all Si5351A will be able to do this. My experience is that a "guaranteed" fmax is 280 MHz.

Bottom line: 300 MHz is a lucky punch, i.e. may work and it may not. I would not put any money on it.

Bo

Forcing the SI5351 to above 1200MHZ VCO e.g. above 300MHz fundamental may overheat the SI5351 and permanently damage it.
So you should be EXTREMELY careful when using a threshold command with values above 300MHz.
Its like tuning a car engine. You may get a more performant engine but it also may explode....

Does that mean that if threshold frequency is set to 250 MHz then instead of 3 x 300 MHz = 900 MHz the operating limit will be 3 x 250 MHz = 750 MHz?

Yes and no, it means the nanoVNA will transition to 3/5 harmonics mode at 250MHz till 750MHz and use 5/7 harmonics mode above 750MHz.
All nanoVNA's with modern software can operate till 5 times the threshold value, whatever the threshold value is. The SI5351 may not lock (PLL lock error) or overheat if the threshold is too high.

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

There is also a physical explanation why the imperfections of SOL standards are described (of parameterized) in a certain way.
The connection from the VNA goes through the connector (which has a certain characteristics impedance into S, O or L.
The connector contains a center conductor, a dielectric and the outer solid metal wall. The characteristic impedance of the connector (and the cable if being used) depends on the size of the center conductor, the thickness of the dielectric (and its dielectric constant) and the outer wall. NOw as long as this continues the impedance stays characteristic. So what does a S, O and L do?
It makes a transition to a new impedance (0, infinite and Z0 for the perfect Short, Open and Load).
But this transition is difficult to make perfect.
The simplest is the Short. You stop the dielectric at a well defined place (called the "reference plane") and make a massive metal (solder or some other metal) connection between the central conductor and the outer wall. But as the connection is not perfect it could have a bit of induction and therefore the imperfections of the short are often modeled as the fixed induction (H) in series with the Short. The induction of the short can be modeled (e.g calculated from the physical characteristics), measured as described in the last document I shared, or "compared" to a known golden standard Short (and yes, even the kilo has to start somewhere)
So the inductive terms used to describe the short are there because they are actually present in the short!!!! They are not "invented" to compensate for imperfections. They describe in as few parameters possible the actual impedance of the short.

The Open is also fairly easy to make at a well defined place (called the "reference plane" ) by stopping the center conductor, the dielectric and the outer wall. Of course you will immediately understand this can never be a perfect "Open", yes, at zero Hz the impedance will be huge (infinite?) but there is a tiny capacity because the center conductor and the outer wall still can "see" each other through the air as the dielectric constant of air is not zero. So this imperfection is calculating from a physical model and specified as capacitance because that is what is actually making the "Open" not perfect.

For the "Load" you have to replace the metal of the Short with some material with a certain resistance to create exactly the right resistance which is easy at zero Hz but from the physical reality you can easily understand there is possibly some inductance (the resistance material has a certain "length" to cover from center conductor to outer wall) or capacitance (the resistor has some "depth" and you no longer have the characteristic impedance of Z0 so there is some extra capacitance.

As a small amount of parallel capacitance has about the same impact as some extra length the capacitive imperfections are sometimes described as shifts of the reference plane.

So in one sentence: The parameters used to model the real impedance of the calibration loads are chosen to match real physical imperfections present in the calibration loads

Now your question related to "real high frequencies". As you can understand extra capacitance has more impact at higher frequencies so that is why you see sometimes calibration loads that deviate substantial at very high frequencies from their perfect impedance at zero Hertz.
This is not a problem but it is reality!!! and as long as you use the real impedance of the calibration loads as (O,S,L) in the G formula there is no problem as the G formula will still be able to calculate G from the measured g, the measured s,o,l and the real impedances S,O and L.
Now what will happens if you calibrate the VNA using the real OSL and the measure one of the calibration standards? You get O, S and L with all their deviations from perfections, which you do not care about because they have no impact on your measurement.
Example. If you have a load with a fringe C you see a resistance with a small C, which may become VERY visible at very high frequencies, even if it is small.

In the documents I added you can see there are many more ways to calibrate out and compensate the internal imperfections of the VNA using various (imperfect) calibration standards and complicated measurement "tricks"
This implies you can physically model and precision manufacture calibration stands as "gold" standards (like with the meter, defined from the speed of light and the second) with impedances calculated from these model and then build a metronomy chain to the much more imperfect calibration standards we normal people use.

Sorry for the long post, I got carried away.....
--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

In addition to what Erik just said, if you ever perform a full clearconfig command via the console or install new firmware, you will need to reset the threshold level again.

Hello,

I'm new here on the list, been a nanovna user for a couple of months now, otherwise a long time VNA user, from HP8410 times onwards.

Just to add my 1.9999 cents...

I find nanoVNA really great. It's main advantage for me is that it is a self contaiend unit. There have been previous amateur VNA constructions, but you always had to connect a computer, a power supply, a coupler, mess of cables, etc.

The small size is also great, it is in fact the first device that lets me measure the antenna match on a handheld device - no need to stick ferrites on a cable or other funny contraptions. In my younger years, I often had to lug something like an HP8753 up a telecoms tower, and then the mains cable drum... Even an FieldFox or SiteMaster is big and heavy when you are climbing a precarious ladder.

So regarding display size - maybe if I live to be 90, I will have a problem reading it. But now, at sixty, I can read it very well, without any problems. Also no problem using the touchscreen with a fingernail. So if you make a bigger screen version, keep making a small display (like current) version too.

SMA connectors - some people have expressed concern about their lifetime. However, that lifetime is specified for every time fastening with a torque wrench, for full performance at 18GHz. Tightening by hand (most of the time) and for 3GHz, the lifetime will be AT LEAST 10X more cycles. Also, you can put those small male/female extenders on, to square the lifetime. Negligible at 3GHz. BNC have no repeatablity and N are HUGE (in nanoVNA terms), so I vote for SMA to stay.

My suggestion would be: keep everything as-is, just extend the electrical parameters, like frequency range, dynamic range, directivity...
And please do not litter this little gem with bluetooth or similar crap. A RF measuring instrument works much better withouta built-in QRM source!

Marko Cebokli

It said my jpeg is processing but I am not sure it uploaded.

Officially the maximum output frequency of any SI5351 is 800MHz divided by 4 is 200MHz.
Many will be able to produce 300MHz but the increase of the VCO of the internal PLL to 1200MHz implies the SI5351 will become much hotter and it is being considered "out of spec"
So you can not formally buy a SI5351 that will go to 300MHz.

If you have a problem with the SI5351 on a nanoVNA not being able to reach the out of spec 300MHz there is a build in solution that will reduce the maximum frequency of the SI5351 before it switches to harmonics mode.

You need to connect to the nanoVNA in console mode using a terminal emulator (putty or any other) and use the "threshold" command to verify at which transition to harmonics mode the problems disappear. This could be any value between 200 and 300 (MHz). Once found you do a "save conf" from the console to store the max threshold value so it will be remembered even if you power off.


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

On Wed, Jan 8, 2020 at 04:54 AM, KE8CPD wrote:

" Can anyone point to the correct chip? or any other tips to make my nanovna work about 300 mhz. "
=================================================================
The NanoVNA only works to 300 MHz on fundamentals. Operation to 900 MHz or 1500 MHz is done using 3rd or 5th harmonics of the fundamentals. Although the si5351a is only spec'd to 200 MHz, it can be used to 300 MHz without cherry picking.

- Herb

Hi Gary,

Regarding fringe capacitance, HP states that fringe capacitance can have an effect on measurement accuracy above about 300 MHz.

This should explain “why” knowing fringe capacitance is important. (And I hope it is already clear why you need to accurately know your standads’ Gammas).

By the way, different types of standards will have different values of fringe capacitance. The Gammas of different Opens aren’t simply a difference in “length change”.

Finally, I would like to add...

Someone once told me that it took HP 10 years to develop VNA error correction. If true, that would have been a tremendous amount of effort by a group of very talented scientists and engineers.

I’m just a retired engineer with a tangential interest in VNA’s. I won’t have the answers to all your questions, but I’ll try to answer what I can.

Best regards,

Jeff, k6jca

On Wed, Jan 8, 2020 at 01:09 PM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:

Rudi,
The problem is the connector used on that is totally unsuitable. It is not
designed for repeated connections. Even the original manufacturer of the
device, Hirosose, rate it at 20 connections/disconnections. Hirose doesn't
release the diagram of the connector, so every cheap connector is going to
be some variation on that.

I almost choked with laughter when I read the word “knockoffs” being
mentioned by the maker of that board. It just seemed strange to think
anyone would knock off a design that’s so obviously flawed, and so easy to
improve (change connectors to SMA).

You should use a special tool for removing them. This one is made by
Hirose, who designed the U.FL connector.



So the design is so fundamentally flawed it is beyond belief. Anyone that
buys one can expect problems.
Dave

Hello Dave,

Thank you very much for the hint with the *extraction tool* for the U.FL connector.
Unfortunately it is *more expensive* than the *RF Demo Kit*.
I am using a 1.0 mm wide flat screw driver for extracting.
Up to now it works fine, if you press the cable down with your finger,
while you are levering with the screwdriver.

I agree, if you handle the U.FL connector *careless*, you will have sooner or later a *problem*.

By the way the data sheet from Hirose tells about *Durability* the number *30* not 20 cycles.
Compared with normal open milk, which is sour for sure after about a week, if not cooled,
the number of plugging cycles for an U.FL plug is a *minimum of 30*,
with a *good probability of more*, if you handle it *careful*.

For me it is a *learning tool*.
There are 25 connectors on the board, on 18 Test fields.
So, if you test and document each Test field once, including calibration,
you are still under the number of 30 cycles.
Beside that, you have *2 cables*.

Why do you score off a useful cheap learning tool, without trying that yourself?

Have you had a look to my "RF Demo Kit" description at:
/g/nanovna-users/wiki/RF-Demo-Kit-use

73, Rudi DL5FA

On Wed, 8 Jan 2020 at 05:51, Gabriel Tenma White <OwOwOwOwO123@...>
wrote:

Test setup: a slightly higher end VNA was used ;) and set to 10 frequency
points, 50x averaging (so that values are noise free but still updates fast
enough). The pk-pk phase jitter observed after calibration was less than
0.1 degree. The cable under test is then connected to port 1 of the VNA,
and the other end of the cable is left open. I then bend the cable randomly
for 1 minute while keeping to a turn radius limit of 5cm, and record
maximum and minimum observed phase. The resulting (max - min) phase error
is then divided by two (because we are measuring reflection, and signals
travel up and back for 2x phase effect).
The numbers shown below are pk-pk transmission phase variation during the
bend test.

It's good to see some quantitative measurements made, but I believe the
test procedure could be improved.

Essentially it is irrelevant what the peak phase changes are when the
cables are in motion. What is important is what phase changes occur after
they have been moved. I find cables take about 30 seconds to settle back.
So my method would be to make a connection, wait 30 seconds, make another
measurement, wait another 30 seconds etc. Of course, it takes more time,
but is more representative of what one would do in a lab, and should give
better results.

Dave

All,
In a effort to repair my NanoVNA to work above 300 mhz, please see /g/nanovna-users/topic/34518859#4791. So i order a new si5351a chip, and replaced it last night. The new chip did not help solve the issue, i though i had matched the chip to original spec but upon further inspection of the spec sheet show to max freq to be only 200 mhz. The link to what i ordered is below. Can anyone point to the correct chip? or any other tips to make my nanovna work about 300 mhz.

On Tue, 7 Jan 2020 at 15:04, <reuterr@...> wrote:

The RF Demo Kit NWDZ Rev-01-10 is available via Ebay for about 15 EUR.

If you buy one and it fails, I would report via eBay as poor quality. You
will soon get your money back.

Dave