Re: Pitfalls of measuring components with the NanoVNA
#measurement
I also tried a very harsh test with the nanoVNA. I put two 820pF PPI 1111 caps in series and compared the ESR to just one 820pF PPI cap. In theory, the ESR should double and the Q curve should be the same.
The result below is quite good but this is really stretching the limits of any VNA. The result for two caps in series isn't quite double the ESR but it looks close enough.
Note that I'm not doing anything 'clever' with calibration offsets or fudge factors to get these results. I measured the OPEN and SHORT delays on a lab analyser and I use this to correct any slight error in the cal kit. The difference betwen open and short is only about 2ps even uncorrected. So there is no secret sauce or fudgery involved in the setup I'm using.
I did note that the edelay 'delay' needs to have a x2 factor included (to give the correction delay I expect) and I'm not used to seeing this.
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Re: Pitfalls of measuring components with the NanoVNA
#measurement
I'm fairy sure my nanoVNA is an H as it had H firmware on it when it arrived. It was made in 2019 and is the open frame 2.8" model. At the time I did try and buy from a proven seller to get a well made example with the screens and battery fitted.
I didn't keep any notes when I experimented with newer firmware but I think the newer versions of FW that I struggled with were the Dislord 1038 FW and the (latest?) oneeleven FW. Both of these gave much noisier results and I do remember trying different bandwidths. I may have missed something though. I didn't spend much time with either version so maybe I should have given them a better chance. I found that all of the Edy555 versions of FW that I tried seemed to give a clean trace on a 100k and a 1R resistor test. I tried quite a few right up to version 080. However the two most recent versions 070 and 080 seemed to be prone to freezing up and I think this was caused by my own PC tools that I use to communicate with the nanoVNA. I think 070 and 080 have some of Dislord's code in and I'm fairly certain that both these versions were as good as earlier versions in terms of the RF performance. It was just the freezing up issue that stops me using these newer versions. At the moment I'm running 060 FW and this is quite old and it doesn't have as many features. However, it seems to run reliably with my PC tools.
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Re: Saving .s1p, .s2p, and Screenshots Directly from the nanoVNA-H4
Oops, for size, do you mean capacity or physical?
It takes an microSD card also known as a TF card of any capacity?
I've used a 32GB and 32MB without any problems
On Wed., 24 Mar. 2021 at 7:10 p.m., n2msqrp<mstangelo@...> wrote: I just got a new H4 form R&L Electronics and it has the SD receptacle. What size SD card does it accept?
Mike N2MS
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On 03/24/2021 3:26 PM Larry Rothman <nlroth@...> wrote:
In DiSlord firmware, the screenshot works if you click on the centre, bottom of the screen.
You can add a 32KHz xtal on the PC14-PC15 pins at the bottom edge of the H4 PCB, then set using the time cmd in the console.
? ? On Wednesday, March 24, 2021, 2:40:46 p.m. EDT, Ken Moorman <nu4i@...> wrote:
? Several months ago, possibly last year even, there was some discussion here
about the nanoVNA-H4 as having built onto the boards either a jack that
would accept micro-SD cards or at least the circuit pads were present for
the installation of said jack if it had not actually been soldered on by the
manufacturer.? I also remember that there was discussion about adding a
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Re: Saving .s1p, .s2p, and Screenshots Directly from the nanoVNA-H4
I just got a new H4 form R&L Electronics and it has the SD receptacle. What size SD card does it accept?
Mike N2MS
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Show quoted text
On 03/24/2021 3:26 PM Larry Rothman <nlroth@...> wrote:
In DiSlord firmware, the screenshot works if you click on the centre, bottom of the screen.
You can add a 32KHz xtal on the PC14-PC15 pins at the bottom edge of the H4 PCB, then set using the time cmd in the console.
On Wednesday, March 24, 2021, 2:40:46 p.m. EDT, Ken Moorman <nu4i@...> wrote:
Several months ago, possibly last year even, there was some discussion here
about the nanoVNA-H4 as having built onto the boards either a jack that
would accept micro-SD cards or at least the circuit pads were present for
the installation of said jack if it had not actually been soldered on by the
manufacturer.? I also remember that there was discussion about adding a
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Re: NanoVNA -H4 and new Dislord 1.50 SW... Odd problem?
Hello DiSlord,
T`hanks for the fast response, I reloaded 1.0.50 again and now it works... (?)
I'm not sure what I did wrong before, but now it is working fine, its also much faster, which is great!
My apologies for the false alarm.
Best!
Steve
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Re: Saving .s1p, .s2p, and Screenshots Directly from the nanoVNA-H4
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Re: NanoVNA -H4 and new Dislord 1.50 SW... Odd problem?
For run/pause sweep need set/remove flag on Stimulus->Pause sweep
On direct connect CH0 to CH1 port you should see S21 at 0 (if all work and calibration correct) on both port open ess noise at bottom.
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Re: Saving .s1p, .s2p, and Screenshots Directly from the nanoVNA-H4
Thanks for the information, Larry. Does the clock have to be working for the screenshot and s1p, s2p to be saved? Or do I just have to plug in a micro-SD card to get it to work? I guess the saved files could be given a time stamp from the clock instead of naming them. Have you already made these mods to the board yourself? It sounds like the crystal (is it a 32khz clock crystal) is mounted on the board edge rather than tacked onto the MCU as I had been thinking. That would certainly make the mod a lot easier! If you have any pictures or other info that would be useful I would really appreciate it.
Ken, NU4I
Sent from my iPod
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On Mar 24, 2021, at 15:26, Larry Rothman <nlroth@...> wrote:
In DiSlord firmware, the screenshot works if you click on the centre, bottom of the screen.
You can add a 32KHz xtal on the PC14-PC15 pins at the bottom edge of the H4 PCB, then set using the time cmd in the console.
On Wednesday, March 24, 2021, 2:40:46 p.m. EDT, Ken Moorman <nu4i@...> wrote:
Several months ago, possibly last year even, there was some discussion here
about the nanoVNA-H4 as having built onto the boards either a jack that
would accept micro-SD cards or at least the circuit pads were present for
the installation of said jack if it had not actually been soldered on by the
manufacturer. I also remember that there was discussion about adding a
small clock crystal directly across two pins on, I believe, the SMT MCU.
This would allow the user to set the clock using a terminal program like
Putty. Firmware was also being written to support these two features, I
believe. I was too busy with other problems on my learning curve for
nanoVNA use that I didn't save any of the discussions then. I have a
hardware version 4.2 which has the micro-SD card jack already added and have
added a slot to the case for it. I have upgraded the firmware to Dislord's
latest version, v1.0.50, which has the menu item "SD CARD" on the Main Menu.
Tapping on that brings up the next menu with "SAVE S1P" and "SAVE S2P".
There was also something said, I thought, about saving screenshots on the
nanoVNA-H4 to the micro-SD card but I haven't seen a menu item for that yet.
I have not tried plugging in a card yet but when I tap on either of the save
commands nothing seems to happen and I get no error message. If anyone has
discovered how to use any of these functions including the clock I would
really like to learn what you know. And if all this is yet to be
implemented I would like to know that as well. Being able to save the s1p
and s2p files in the field would be a very nice feature, as well as being
able to retain screenshots. I have used my phone to take pictures of the
screen but saving them to the card would be great and wouldn't take any
effort.
Ken, NU4I
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NanoVNA -H4 and new Dislord 1.50 SW... Odd problem?
Hello All. I have a NanoVNA H-4, and I have been using DiSlord's 1.45 SW for about 9 months.
It is great,. it's stable and performed as expected.
I recently discovered the new 1.50 SW and decided to upgrade as it '"'faster" .
So, I upgraded to the new 1.50 SW revision, it loaded just fine, and calibrated etc as usual.
My problem however is odd, I wanted to test a 25MHz Elliptic LPF, using the S21 mode and LogMag. I use this mode often.
the problem is that I see nothing measured... just low level noise at -80dBm... Its almost like the RF sweep is not working to be measured.
I reloaded 1.50 and see the same thing. I then reverted to the older 1.45 SW and normal operation is resumed. My filter looks good.
I cannot find any menu mode to "turn" on the Sweep; is this a bug, or is there some extra mode or menu option I have not yet found to test S21 / LogMag?
I'd appreciate any suggestions.
Thanks!
Steve Mahrer
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Re: Saving .s1p, .s2p, and Screenshots Directly from the nanoVNA-H4
BTW,? have a look at OneOfEleven's nanovna-app program - it takes screenshots,calibrates the device and a lot more. The link is in her github account but you can find the link by searching for nanovna-app in the forum messages.
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On Wednesday, March 24, 2021, 3:28:24 p.m. EDT, Larry Rothman <nlroth@...> wrote:
In DiSlord firmware, the screenshot works if you click on the centre, bottom of the screen.
You can add a 32KHz xtal on the PC14-PC15 pins at the bottom edge of the H4 PCB, then set using the time cmd in the console.
? ? On Wednesday, March 24, 2021, 2:40:46 p.m. EDT, Ken Moorman <nu4i@...> wrote:
Several months ago, possibly last year even, there was some discussion here
about the nanoVNA-H4 as having built onto the boards either a jack that
would accept micro-SD cards or at least the circuit pads were present for
the installation of said jack if it had not actually been soldered on by the
manufacturer.? I also remember that there was discussion about adding a
small clock crystal directly across two pins on, I believe, the SMT MCU.
This would allow the user to set the clock using a terminal program like
Putty.? Firmware was also being written to support these two features, I
believe.? I was too busy with other problems on my learning curve for
nanoVNA use that I didn't save any of the discussions then.? I have a
hardware version 4.2 which has the micro-SD card jack already added and have
added a slot to the case for it.? I have upgraded the firmware to Dislord's
latest version, v1.0.50, which has the menu item "SD CARD" on the Main Menu.
Tapping on that brings up the next menu with "SAVE S1P" and "SAVE S2P".
There was also something said, I thought, about saving screenshots on the
nanoVNA-H4 to the micro-SD card but I haven't seen a menu item for that yet.
I have not tried plugging in a card yet but when I tap on either of the save
commands nothing seems to happen and I get no error message.? If anyone has
discovered how to use any of these functions including the clock I would
really like to learn what you know.? And if all this is yet to be
implemented I would like to know that as well.? Being able to save the s1p
and s2p files in the field would be a very nice feature, as well as being
able to retain screenshots.? I have used my phone to take pictures of the
screen but saving them to the card would be great and wouldn't take any
effort.
Ken, NU4I
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Re: Saving .s1p, .s2p, and Screenshots Directly from the nanoVNA-H4
In DiSlord firmware, the screenshot works if you click on the centre, bottom of the screen.
You can add a 32KHz xtal on the PC14-PC15 pins at the bottom edge of the H4 PCB, then set using the time cmd in the console.
toggle quoted message
Show quoted text
On Wednesday, March 24, 2021, 2:40:46 p.m. EDT, Ken Moorman <nu4i@...> wrote:
Several months ago, possibly last year even, there was some discussion here
about the nanoVNA-H4 as having built onto the boards either a jack that
would accept micro-SD cards or at least the circuit pads were present for
the installation of said jack if it had not actually been soldered on by the
manufacturer.? I also remember that there was discussion about adding a
small clock crystal directly across two pins on, I believe, the SMT MCU.
This would allow the user to set the clock using a terminal program like
Putty.? Firmware was also being written to support these two features, I
believe.? I was too busy with other problems on my learning curve for
nanoVNA use that I didn't save any of the discussions then.? I have a
hardware version 4.2 which has the micro-SD card jack already added and have
added a slot to the case for it.? I have upgraded the firmware to Dislord's
latest version, v1.0.50, which has the menu item "SD CARD" on the Main Menu.
Tapping on that brings up the next menu with "SAVE S1P" and "SAVE S2P".
There was also something said, I thought, about saving screenshots on the
nanoVNA-H4 to the micro-SD card but I haven't seen a menu item for that yet.
I have not tried plugging in a card yet but when I tap on either of the save
commands nothing seems to happen and I get no error message.? If anyone has
discovered how to use any of these functions including the clock I would
really like to learn what you know.? And if all this is yet to be
implemented I would like to know that as well.? Being able to save the s1p
and s2p files in the field would be a very nice feature, as well as being
able to retain screenshots.? I have used my phone to take pictures of the
screen but saving them to the card would be great and wouldn't take any
effort.
Ken, NU4I
|
Saving .s1p, .s2p, and Screenshots Directly from the nanoVNA-H4
Several months ago, possibly last year even, there was some discussion here
about the nanoVNA-H4 as having built onto the boards either a jack that
would accept micro-SD cards or at least the circuit pads were present for
the installation of said jack if it had not actually been soldered on by the
manufacturer. I also remember that there was discussion about adding a
small clock crystal directly across two pins on, I believe, the SMT MCU.
This would allow the user to set the clock using a terminal program like
Putty. Firmware was also being written to support these two features, I
believe. I was too busy with other problems on my learning curve for
nanoVNA use that I didn't save any of the discussions then. I have a
hardware version 4.2 which has the micro-SD card jack already added and have
added a slot to the case for it. I have upgraded the firmware to Dislord's
latest version, v1.0.50, which has the menu item "SD CARD" on the Main Menu.
Tapping on that brings up the next menu with "SAVE S1P" and "SAVE S2P".
There was also something said, I thought, about saving screenshots on the
nanoVNA-H4 to the micro-SD card but I haven't seen a menu item for that yet.
I have not tried plugging in a card yet but when I tap on either of the save
commands nothing seems to happen and I get no error message. If anyone has
discovered how to use any of these functions including the clock I would
really like to learn what you know. And if all this is yet to be
implemented I would like to know that as well. Being able to save the s1p
and s2p files in the field would be a very nice feature, as well as being
able to retain screenshots. I have used my phone to take pictures of the
screen but saving them to the card would be great and wouldn't take any
effort.
Ken, NU4I
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Re: Newcomer - Advice sought please -Edelay appeared and calibration awry
Roger,
My apologies for the late reply, delivering curry, toilet rolls and various biscuits around the country has kept me away from home.
Thank you very much, will look into this as I am now off for 12 days.
Very much appreciated.
Kev
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Re: Pitfalls of measuring components with the NanoVNA
#measurement
JMR,
You have a NanoVNA-H. Correct? Which version of firmware are you using for best results? I will try to make a comparison since I have -H and -H4 NanoVNAs.
Roger
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Re: Pitfalls of measuring components with the NanoVNA
#measurement
I can try the latest firmware to see if things are improved but can you post up a link and a version number to try?
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Re: Pitfalls of measuring components with the NanoVNA
#measurement
Hi Dislord, thanks for the reply.
I don't know if this is useful but I did briefly try several versions of newer firmware (including yours) on my nanoVNA-H and I found the performance wasn't as good when doing critical tests like this. I assumed something had been compromised for faster detection/sweep. So I've gone back to a very old version of firmware to get this level of performance.
I guess not many nanovna users will explore the limits of the instrument like this. I'm a career long user of VNAs and I do try and squeeze as much performance out of them as I can. I also can create custom L0-L3 and C0-C3 correction factors for some of my cal kits to really make them work well through several GHz.
I don't know what the detection bandwidth is in the version of firmware I'm using as it is fixed but I did try several newer firmware versions and I did try the lower RBW options and I still couldn't get the same performance. Only a handful of nanoVNA users will be as critical as me so I'm not sure how much this matters.
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Re: Pitfalls of measuring components with the NanoVNA
#measurement
Can you get last NanoVNA firmware and made measure vs small bandwidth setthing (30Hz ?)
This should reduce noise
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Re: Pitfalls of measuring components with the NanoVNA
#measurement
Here's the nanoVNA attempting the same test. This is a really nice (expensive!) PPI 1111 560pF cap in series with a 0.333R resistor and also just the PPI 560pF cap without any added resistance.
The nanoVNA gets the 0.333R ESR test spot on.
At first glance the lower trace showing the measurement of the 0.03R ESR of the 560pF cap looks really good but the noise on the trace will make a Q curve look very jagged. These results are worlds apart from the incompetent team who wrote the paper about capacitor ESR that Roger linked to a few posts ago.
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Re: Pitfalls of measuring components with the NanoVNA
#measurement
OK thanks. I've not studied the nanoVNA beyond the input to the ADC so I don't know how it does things in firmware.
To try and counter the research article that Roger linked to I dug out another PPI 1111 SMD cap. This one is 560pF and the datasheet shows a falling ESR from about 0.03R up at VHF.
I also measured a decent 1R 1% SMD resistor to 50MHz to try to prove it was 1R and flat to within 0.02R up to 50MHz. I then put three resistors in parallel and put this in series with the 560pF cap. The total ESR of the cap + resistor should therefore be just over 0.333R.
The plot below was taken with my Agilent VNA and it shows that this is the case. I also measured the 560pF cap on its own and it had a decent stab at measuring the ESR which should be about 0.03R at the top end according to the datasheet.
Modern VNAs are really amazing devices. I'm not sure I trust the ESR reading of the raw 560pF cap as this really is stretching the limits of the VNA. However, to get this level of performance the whole test fixture and the cal kit are very important as is the experience of the operator.
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Re: Pitfalls of measuring components with the NanoVNA
#measurement
On 3/23/21 7:48 PM, Roger Need via groups.io wrote: On Tue, Mar 23, 2021 at 07:24 PM, jmr wrote:
I've not actually looked inside my nanovna but a quick glance at the online
schematic shows a classic resistive bridge. When you connect a test circuit to
the CH0 input the bridge in the nanoVNA should output a signal that measures
to have the magnitude of the reflection coefficient. It will also have the
phase of the reflection coefficient. The LO + NE612 mixer converts this down
to 5kHz where it can be sampled with an ADC and measured in relation to the
reference signal in terms of amplitude and phase. The reference is also mixed
down to 5kHz.
If the ADC after the NE612 mixer says the 5kHz signal is shrunk to 99.9% of
the size of the 5kHz reference input then the reflection coefficient is 0.999.
If the 5kHz signal has a phase of -112degrees with respect to the 5kHz
reference then the angle of the reflection coefficient will be -112degrees.
That's the way I assume the system works. I don't see why you and Jim think
the bridge generates I and Q signals. What am I missing here?
JMR,
Please read carefully what I wrote. I did not say the "bridge generates I and Q signals". But it is not as simple as you say. Here is edy555 commenting on the original design. How is it done now? I don't know...
/g/nanovna-users/files/Miscellaneous/NanoVNA%20design%20notes%20by%20edy555/Calculate%20reflection%20coefficient%20from%20NanoVNA%20signal%20and%20plot%20frequency%20characteristics.pdf
Rather than you or I speculating I hope someone here that knows the firmware details can comment. The I/Q measurement is done in dsp.c, in routine dsp_process() which takes 48 raw samples in *capture and turns it into two I/Q pairs. *capture is 32 bits, the low order 16 bits are the reference, the high order bits are the measurement. The actual calculation takes the two 16 bit numbers (input and either sin or cos) multiplies them, then divides by 16? and adds it to an accumulator. I assume the divide by 16 is to make sure that the sum doesn't overflow when summing 48 copies.? The sin and cos table is pretty close to full scale (32698, full scale would be 32767), so I assume the gain in front of the adc (or the signal levels) so that the divide by 16 and sum over 48 keeps it from overflowing.
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Kev Haworth
Roger Need
