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This is my first post after lurking since October, so I'm quite new to the Nanovna. The Nanovna measurements of SWR are considerably lower than what I'm seeing when I transmit on-the-air. What does this indicate? Calibration problems, or errors in my other equipment? Any insight would be greatly appreciated. Thanks.
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Ron, K7UV

Hello Rune,
thank you for investing in the development of this measurement aplication very very close to the professional.
I draw your attention to the TDR function or indeed the length marker is really good, I think it would be very good that there is in addition to the metric datum Z data and vswr. when you think it's just a matter of reading comfort.
Of course you can always reduce the Z-forearm.
but it lacks a little precision.
can be seen in a future version.
sorry i'm going through an online translator
best 73's eric F4IAB

Hello again,
Thank you for the replies, and thank you Larry particularly. That was just what I needed.
Well, I am not going to claim every single one of the 7000, because some are repetitive,
and I wasn't counting! But it certainly seemed like it.
And I had read that very very useful .pdf file of course. I am glad that I pointed out a need,
and sorry that your finished document now needs an addition. From my days teaching I
really do know that feeling!
Thanks again.
Tony...

In post 1257: /g/nanovna-users/topic/32993803#1257
I calculated the output impedance of CH0 to be 51.53 ohms
and the input impedance of CH1 to be 53.85 ohms.

In the previous post of that thread, Alan got 51.27 ohms for CH0.
There's a bunch of assumptions being made in those calculations,
it would be interesting to measure these figures accurately.

The discussion about correction factors in post 1311
is continued in a different thread with post 1318

Jerry, KE7ER

That's probably a safe way to go, but the -H schematic is still showing the SD103AWS schottky while the STM32F072CBT6 datasheet has 4.0 max for the VBAT pin... not a lot of margin there.

Hi Herb

I have done a lot of such measurements in the past and eliminated the inductance of the wire thru the core.

In your setup I think you get even better result by doing a SOL calibration at the end of the BNC adaptor using the Shorting wire thru the core without the core as short and place a leaded 50 ohm resistor as load and nothing for the open. The you get eliminated the "funny" impedances of the adaptors in the calibration process
To take it a step further read the documents



I use some closed chambers (e.g. tin can for paints with a small SMA female female adaptor in the lid and a shorting pin internally) and in a spread sheet calculate the inductance. In another spreadsheet convert S11 to impedance and subtract the shorting pin inductance
That is the nerd'ed way a bit but the right way to get better data than the manufacturers using a short wire thru the core ?

Kind regards

Kurt



-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af hwalker
Sendt: 15. november 2019 02:49
Til: [email protected]
Emne: Re: [nanovna-users] NanoVNA-Saver 0.2.0



David F4HTQ wrote:



"finally I do not wait for the weekend :)"



-------------------------------------------------------------------------------------



The test method you described seemed simple enough to give it a quick go. Attached is a photo of the test set-up I used. One turn of wire attached to a Banana-BNC adapter and connected to CH0, hopefully similar to your description.



I pulled out the first ferrite core I could find and measured it. The initial curve from 100k-30M looked like junk below 1M and not enough definition at 30 MHz. I changed the range to 1M -100M. The core is definitely not type 43 and pretty broadband in nature. I measured two other cores just like it and their curves overlapped. Found identifying markings on the cores - Laird type 28B2400-000. Found the curves for Laird 28B on-line and have attached them.



The Laird 28B series is definitely broadband but not sure I could have identified my cores from the Laird curves without priori information. The NanoVNA curves for all three cores did match and I suppose I could build up a signature database and use it to sort unknown ferrites.



Thanks for giving me another idea for using the NanoVNA.



- Herb

The TDR range depends on the frequency step and hence the span. Use lower
frequencies to measure long lengths and higher frequencies to measure short
lengths. The software doesn't know in advance what you want to measure.



On Fri, Nov 15, 2019 at 1:36 PM Barry Jackson via Groups.Io <G4MKT=
[email protected]> wrote:

On 12/11/2019 13:35, Rune Broberg wrote:

Earlier today I released NanoVNA-Saver 0.2.0:

Hi Rune,
Thanks for the new version which is performing well.

One issue that puzzles me is regarding TDR.

This seems to depend on other settings like frequency span, but I have
not yet discovered in which way this dependency works.

If for example I have the VNA set to look at an HF antenna VSWR over the
range 3.5 to 7.2MHz and then click the TDR button, the display shows
nothing of use with X values in the 100km range!

After a couple of days fiddling I tried setting the frequency span to 1
to 500MHz and suddenly started to get results that made sense.

If a particular frequency span setting, sweep mode etc. is needed for
TDR measurements, should not the software set those modes temporarily
when the TDR button is clicked and then revert back to the previous
settings on leaving the TDR screen?

Any help appreciated,

Barry
G4MKT

On 12/11/2019 13:35, Rune Broberg wrote:

Earlier today I released NanoVNA-Saver 0.2.0:

Hi Rune,
Thanks for the new version which is performing well.

One issue that puzzles me is regarding TDR.

This seems to depend on other settings like frequency span, but I have not yet discovered in which way this dependency works.

If for example I have the VNA set to look at an HF antenna VSWR over the range 3.5 to 7.2MHz and then click the TDR button, the display shows nothing of use with X values in the 100km range!

After a couple of days fiddling I tried setting the frequency span to 1 to 500MHz and suddenly started to get results that made sense.

If a particular frequency span setting, sweep mode etc. is needed for TDR measurements, should not the software set those modes temporarily when the TDR button is clicked and then revert back to the previous settings on leaving the TDR screen?

Any help appreciated,

Barry
G4MKT

The design of the Nanovna indicates the use of a standard silicon diode - not Schottky? as a number of members suggest.
The reason for this, is to prevent the input to the uP from going above 3.9V, which is the max input.
A fully charged Li battery is around 4.2V so you don't want to drop the voltage by only 0.2v

So - with that said, use a 1N4148 diode and QRP's latest 0.4.3 firmware that allows you to calibrate the battery voltage displayed.
...Larry

A Schottky would be best but any regular (non-zener) would work. The footprint is SOD323 but most people use a PTH style.

NSR0530HT1G (SMT) or SB530 (PTH) for instance.

Hi Tony,
Welcome to the group.? You read all 7000 posts?!? :-)

The NanoVNA is capable of displaying 1:1 SWR graphically so I'm not sure what you are referring to.
You can change the scale on the display to allow you to see finer resolution.
Have you downloaded a copy of the User Guide from the Files section of the forum?
/g/nanovna-users/files/NanoVNA%20User%20Guide-English-reformat-Oct-2-19.pdf
NOTE: I just realised there is no reference in the translated User Guide that describes how to adjust the scale on the display!!? I'll have to add that section.

In any case, select the Display menu and then select Scale.
From there you can set the reference position (defaults to 7, where 0 is at the bottom and 8 is at the top of the display).
Next, adjust the Scale per division.

For SWR, ensure your display Format is set to SWR for CH0 (obviously) and then select a Scale Reference of 0 (bottom division line on the display).?

Then, set your Scale to 0.1 .The bottom of the display will be 1:1 and each division above will increase by 0.1 (ie: 1:1.1, 1:1.2, 1:1.3).
You can also try a Scale of 0.05 for a finer resolution on the display.
I hope this helps (and thanks for the question - I'll have to update the guide now).
...Larry

Hello Tony,
You can adjust the scale of the swr graph.
Display: scale: scale/div.
73 de Ton PA0ARR

Sounds like a calibration issue.
Mine will correctly show 1.1:1 numerically and graphically, I just checked.

73 de Andy

Hi All,
I have been subscribed to this group for quite a few weeks now, but this is my first posting.
Why? Because it has taken me that long to read through all the previous posts!
Anyway, I have not seen this subject before:
Being an licensed amateur SWR, means much more to me than return loss, which because
of my background I asssociate more with TV equipmentt, so I was a little disappointed to find
that the lowest graphical reading is about 1.3:1. The numeric readout at the top shows the
figure, but the graphical result would be much more useful for making adjustments.
Is this a feature that "comes with the model sir", or is there an adjustment that I have missed?
As a new user I do have other questions, but that is quite enough for now.
Thank you
Tony (G3PTD)

On Fri, Nov 15, 2019 at 01:48 AM, Rich NE1EE wrote:

because now the phase had a lot of jitter.

this "jitter" is just because phase has noise. The phase is limited to -180 to +180 degree, so when it come to -180, you will see jump to +180. Unwrapped phase will not have such "jitter"

I think you can use 220 Ah battery (220'000 mAh) and it should works ok

Hi David,

The .dfu files are used to flah firmware into the? NanoVNA device, you can do that with DFUseDemo software from STI under windows.

Regards

Jos

Op 14-11-2019 om 23:38 schreef David Eckhardt:

Thank you Gyula for the information. I didn't replace any components. I received this complete device with this plug included and without a diode D2. Ok, I'll desolder the connector and will solder the cables directly on the pads. As for the type of diode I found several topics here. Don't know which post to follow. Guess a standard Si diode like 1N4148 should work?

I think the frequency of the cross point of those curves is the most important parameter?

Trimis din Yahoo Mail pe Android

Pe vin., nov. 15, 2019 la 0:06, David F4HTQ<f4htq@...> a scris: Hi All,
I? add some explanations.
I asked Rune if he could add this graphic because it is very useful.
It display curves that have exactly the same shape as the complex permitivity curves (μ'r and μ''r) of the ferrite datasheets.

The values do not match those of the constructor curve ( to have the right value the software might know the exact geometry of the inductor) , but the shape is absolutely identical.

This allow to easy? identify unknown ferrite core, and to better understand how to use it in a RF device.

For example, here is the true curve of material 43 of Fair rite.



And here's the one I got with NanoVNASaver



It works really well.
David, F4HTQ.

Based on the pictures, the socket soldered to the pcb has a 1.25mm plug and the battery has a 2.54mm plug. I suppose you replaced the power plug with a smaller one so that the D2 diode could be soldered afterwards, but why didn't you solder the D2? D2 is required for newer firmware due to power supply indication. The first versions did not have a power connector, and there is no need to change the battery frequently, so I would cut off the battery connector one by one and solder it to the pcb, as is the case with the first versions.
It is understood that there is a positive pole on the D2 side.
In your area, I would ask the merchant for a refund of approx. 15%, I think that could be realistic. Attach a photo when claiming.