Hi Rune,
I have made a large number of routine impedance measurements using your V0.0.10 exe binary under Windows 10 Pro 64b. I have not encountered any stability problems and in general think it works wonderfully well - thank you!
One part of the GUI that I didn't understand intuitively the first few times I used it was the purpose of the "Segments" box. I changed it and nothing seemed to happen. I of course noticed immediately that it is a multiplier for the number of steps in the sweep once I changed it and then happened to do a calibration which shows the number of steps in the sweep. I decided I would like to make a suggestion that I hope is worthy of consideration.
It occurred to me that it would be obvious to the user that the segments setting increases the sweep frequency resolution if the number of Hz per step could be shown. Additionally I think the provision of the "Hz/Step" information would be useful in some situations. For example when sweeping a network with narrow high Q responses the user may wish to select a segments setting that provides a sufficiently small step size to ensure a narrow peak or null is not missed without increasing the sweep time any more than necessary. A second advantage for providing the "Hz/Step" data is that it would provide immediate indication of how a change of the segments setting changes the sweep resolution. This feedback would make the setting more user intuitive I think.
Considering that the number of segments would never exceed two digits and the number of Hz per step would never exceed 7 digits there might be room to fit the two boxes on the existing segments line within the GUI. If for example the "Segments" label were abbreviated to "Segs." with a two digit box then possibly there would be room for another label something like "Hz/Step" followed by a 7 (or 9 if 2 comma delimiters) digit box on the same line. Just might be one of many possible ways to implement it without impacting the existing GUI layout very much.
Thanks again for your great contribution - "NanoVNA-Saver" really enhances the usefulness of my nanoVNA for what I intend to use it for!
Enjoy!
Tom
VA7TA
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Re: Evaluating clamp on ferrite chokes
A |S21| measurement is reasonable. However, the signature for a lossy choke should also be apparent in a S11 measurement. So take a short length of #22 AWG enamel wire and tie it across the CH0 port of the VNA. The inductance measured if it is reasonable length of wire, say 100 nH should follow a CW trajectory on the chart, along the 50 ohm circle (blue). When the lossy ferrite material is added, I would expect an increase in L as well increase in series R. The result is an increase CW rotation over the same frequency swept range as well a shift of the circle contour to the right. See figure (red) . Try it, see what you get.
Alan
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Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
Dave,
The minimum energy to cause damage has gone way down over the years as transistor geometries have shrunk, but I don't know specific values.
When I started doing chip design, the state of the art was with NMOS FET gates around 9 microns by 9 microns in minimum area. Present CMOS transistor gates (in high density digital circuits) are around 7 nanometers by 7 nanometers minimum. In area, that is more than a million times smaller.
RF devices are not normally that small, but you get the idea. Even in a fairly large device, gate oxide damage is usually concentrated in a small weak spot of the overall device, so it doesn't necessarily help a lot if the gate area is large. The usual plan in protecting sensitive circuits is to use things like (relatively) large junction devices to direct ESD currents to supply rails instead of FET gates. These junctions are reverse biased in normal operation, but they still can contribute to distortion problems.
--John
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On Sun, Sep 22, 2019 at 08:25 PM, Dr. David Kirkby from Kirkby Microwave Ltd wrote:
On Mon, 23 Sep 2019 at 02:36, johncharlesgord via Groups.Io <johngord=
[email protected]> wrote:
Dave,
50 ohms to ground provides some protection, but often not enough.
The standard human body model (HBM) for ESD testing is 1500 ohms in
series with 100pF. The 1500 ohms is supposed to represent the impedance of
the discharge path through the body, while the 100pF represents the
capacitance of the body including something like rubber soled shoes to a
grounded surface.
Even at a relatively low static voltage like 1500v, one ampere can
(briefly) flow, causing a drop of 50 volts across the 50 ohm resistor.
Small geometry semiconductors like those used in RF mixers can be damaged
by such a hit. Some situations can generate static voltages that are much
higher.
--John Gord
Thank you. I was unaware of that. Perhaps that¡¯s why my 8720 says no ESD on
the front panel. However, the test ports on that are no 50 ohns at DC, as
there are bias-T fitted too.
I assume that there must be some minimum amount of energy required to
damage a semiconductor.
Dave.
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Re: Evaluating clamp on ferrite chokes
Coil coax around a ferrite and connect the outer shield for a S21 measurement. Loss in S21 = choking :) typical ferrite for line noise choking is #31 (also for top bands 160m - 80m). #43 does a great all-round job on higher bands. #52 is a newer kid on the block. Higher curie temperature, which translates to higher power rating + it's quite capable on all ham bands. All of this from perspective of an HF ham radio operator ;)
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Evaluating clamp on ferrite chokes
Wondering if anyone has tried to use the nanoVNA to evaluate the properties of the clamp on ferrite chokes that are employed to reduce radio frequency interference (RFI) being emitted by wall wart switching supplies etc. I am not sure how one would do that...use some kind of standard pair of wires like an AC line or adapter cord and measure S11 (single end attached) or S21 (both ends attached) with and without the ferrite clamped on? A similar question would be how to evaluate a common mode choke made by coiling coax around a cylinder form of some kind.
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Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
Dr. David Kirkby from Kirkby Microwave Ltd
On Mon, 23 Sep 2019 at 02:36, johncharlesgord via Groups.Io <johngord= [email protected]> wrote: Dave,
50 ohms to ground provides some protection, but often not enough.
The standard human body model (HBM) for ESD testing is 1500 ohms in
series with 100pF. The 1500 ohms is supposed to represent the impedance of
the discharge path through the body, while the 100pF represents the
capacitance of the body including something like rubber soled shoes to a
grounded surface.
Even at a relatively low static voltage like 1500v, one ampere can
(briefly) flow, causing a drop of 50 volts across the 50 ohm resistor.
Small geometry semiconductors like those used in RF mixers can be damaged
by such a hit. Some situations can generate static voltages that are much
higher.
--John Gord
Thank you. I was unaware of that. Perhaps that¡¯s why my 8720 says no ESD on the front panel. However, the test ports on that are no 50 ohns at DC, as there are bias-T fitted too. I assume that there must be some minimum amount of energy required to damage a semiconductor. Dave. -- Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@... Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales. Company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom
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Re: errors of "error" models
Hello,
We just uploaded the currently available version of /F/L/O/S/S/ Maxima code:
as well as, the currently available version of its documentation:
for the Uncertainty Estimation of Full One-Port VNA Measurements.
Next to come : the currently available version of /F/L/O/S/S/ FORTRAN code.
Sincerely,
yin@pez@arg
3
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Why is a rubidium standard at 10 kHz offset from the carrier at 10 MHz that noisy? Is the phase noise floor shown limited by the test set?
Regards, Alan
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Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
Dave,
50 ohms to ground provides some protection, but often not enough.
The standard human body model (HBM) for ESD testing is 1500 ohms in series with 100pF. The 1500 ohms is supposed to represent the impedance of the discharge path through the body, while the 100pF represents the capacitance of the body including something like rubber soled shoes to a grounded surface.
Even at a relatively low static voltage like 1500v, one ampere can (briefly) flow, causing a drop of 50 volts across the 50 ohm resistor. Small geometry semiconductors like those used in RF mixers can be damaged by such a hit. Some situations can generate static voltages that are much higher.
--John Gord
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On Sun, Sep 22, 2019 at 12:10 AM, Dr. David Kirkby from Kirkby Microwave Ltd wrote:
I fail to see the need to worry if the active devices is connected across a
50 ohm resistor. 50 ohms is effectively a short circuit as far as static
is concerned.
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Hello Rune,
Again thank you for your perseverance with the nanoVNA PC Software you are bringing us all! It is very much appreciated.
However I have a question regarding Calibration using your software, I presume that before I set about doing a Calibration in nanoVNA-Saver, and reset it, I should also do a reset of the VNA Hardware itself? Or is this taken care of by nanoVNA-Saver? As I still see the "0" come up alongside the "C" in the left hand sidebar.
73's
Pete
ZL2iK
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Rune Broberg Sent: Monday, 23 September 2019 07:37 To: [email protected]Subject: Re: [nanovna-users] NanoVNA Saver For those waiting for new binaries: I just published 0.0.11 :-) This release brings averaging as a new feature: Press "Sweep settings" to select between running a single sweep (of optionally multiple segments), a continuous (live) sweeping of the range, or to average several sweeps from the NanoVNA. You can configure how many averages to make, and optionally, how many of the sample points to discard, based on which deviate the most from the rest, and are least likely to contribute signal. Also added is a new Resistance/Reactance chart, which shows both the R and X component of R+jX. This brings the challenge of showing two traces for the same data - added is therefore the option of picking a secondary colour for sweeps under "Display settings". There are further improvements to UI sizing, meaning the interface now fits - tightly - on a 1366x768 screen, at least on Windows. A few quality of live improvements made it in: Press escape in any of the pop out windows to close them instantly. The calibration window now shows more clearly when the source of calibration data is loading from a file, and also the number of points loaded. A few crash bugs were fixed. I look forward to hearing feedback from all of you! -- Rune / 5Q5R On Sun, 22 Sep 2019 at 17:14, Mario Vano <mvano@...> wrote: On Sun, Sep 22, 2019 at 06:09 AM, Mario Vano wrote:
CORRECTION: (I mistyped)
- The multi-band dipole is my 20ft high 40/20 meter trap dipole that has
been augmented with parallel dipoles for 15 and 10. The feedline has a
toroid common mode filter.
I've been happily using the NanoVNA and various versions of "Saver" for
a lot
of projects lately, but some were just motivated by curiosity about the
device.
Unfortunately I have no other analyzer to compare to. In any case here are
some sweeps from earlier tests that might be useful for reference or
amusement. In most cases, they were done with my very early attempts at full
bandwidth calibration.
- The fm filter is a commercial product from the rtl-sdr.com people.
- The LW filter is a homebrewed design I use to augment VLF beacon hunting.
- The multiband dipole is my 20ft high 80/40 meter trap dipole that has
been
augmented with parallel dipoles for 15 and 10. The feedline has a toroid
common mode filer.
- The 6 meter antenna is an attic mounted dipole with a toroid common mode
filter.
I've also used happily used the device and "saver" to design and build a 6
meter "squalo", but forgot to save the files from the latest testing run. I'm
currently working on a 400-700 mhz indor LPA design and plan to try to use the
device for relative pattern and gain testing.
Earlier tests with several types of 500-900mhz 1/4 wave mag-mount antennas and
TV rabbit ears showed useful relative gain results at 2-3 wavelength spacings.
73, AE0GL
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Re: Using nanoVNA to measure the directivity of a directional coupler
Here is my RF-bridge measurement. I have blue RF-bridge with two installed jumpers.
I'm using more standard RF bridge measurement method:
1) Open CAL menu and calibrate OPEN/SHORT/LOAD as usual
2) Connect two 50R terminators to CH0 and CH1 and calibrate ISOLN
3) Connect CH0 to the bridge Input
4) Connect CH1 to the bridge Output
5) Connect 50R terminator to the bridge REF
6) Leave bridge DUT connector open
7) Calibrate THRU and then press DONE and close (no need to save)
8) Connect second 50R terminator to the DUT connector
9) Measure S21
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Re: Comparing antenna gain process
Thanks for the Wiki links, they help understand what's going on
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Re: Comparing antenna gain process
Thanks to the pointer on the specific edition on the antenna handbook, it was an easy find on ebay
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Re: RX-Port Input Impedance
On Sun, Sep 22, 2019 at 11:57 PM, Kurt Poulsen wrote:
Incorrect, that is not a measurement of the CH1 input impedance. The cable
between Ch0 and Ch1 create impedance transformation.
Actually, you're right my previous screenshot was taken with no calibration for cable end plane. :) Previously I already performed this measurement with calibration for cable end and without and didn't found significant difference for VSWR measurement. So I simply repeated measurement with no full calibration for my previous screenshot. But how did you found that this is not cable end calibration? :) Here is measurement with full calibration at the end of cable, you can check it on TDR screenshot. As you can see VSWR is almost the same. I'm using good quality 10 cm RG405 cable, so it doesn't affect VSWR measurement much even with no calibration on cable end. I also tested CH1 with another type VNA and it shows the same result.
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Re: nanoVNA Output Voltage
This is the output from my NanoVNA as measured on an HP 8568B spectrum analyzer in Max Hold mode (50 Ohm input impedance). See attached photos.
~10 MHz -13 dBm
~100 MHz -9 dBm
~300 MHz -9.60 dBm
~600 MHz -20.6 dBm
~900 MHz -23.2 dBm
Therefore, there is an approximately 10 to 13 dBm drop in output level going above 300 MHz which is understandable due to the higher frequencies being derived from harmonics. What I am puzzled by is why the output is low (in the -13 dBm range) for frequencies below 100 MHz?
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Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
Yes, I see the point being made now.
I wonder if one of these mats could be used as a ground plane....
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I believe the point that Dave Jones was making, is that the surface
resistance of the mats does not have any adverse effects on 99.99% of the
measurements one makes. I don't think his aim was to show how good a
static dissipative mat was - only that it does not have any adverse
reactions.
It's generally considered unsafe to ground the mats - instead they should
be connected to ground by via a high-value resistor - typically 10 M ohm.
I personally don't think people need to worry about static on the test
ports of the NanoVNA. However, since the sides of the NanoVNA are open in
the standard unit, then there's a possibility of static doing damage there.
Dave
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Rune, thank you very much for NanoVNA-Saver software. Your software is fantastic and you amaze me with all the improvements and features you continue to add. I really like that in all fit into my 1366x768 screen. WOW!
Steve_WB8GRS
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Re: Using nanoVNA to measure the directivity of a directional coupler
Rudi,
I totally agree with you than an applications note section would be a welcome addition to the "Files" category of this user group. The group is approaching 3000 messages and it is getting harder to use the search button to locate specific content . A lot of new users come here with some familiarity using antenna analyzers, and zoom in on the SWR measuring capabilities of the nanoVNA. It is only after being exposed to the nanoVNA's numerous measuring capabilities by other users, that they come to realize the nanoVNA also can measure tdr, attenuation, gain and impedance. At $50, it provides a cheap hands on education that can help to improve your job skills or better enjoy your hobby.
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I recently made a phase noise measurement with my HP 8568B analyzer and KE5FX excellent software. In the picture enclosed pink line is the nanoVNA plot. For reference the blue line is from my 10MHz rubidium reference. This probably gives the lower limit of this setup for signals up to ~200kHz.
Ernst
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Re: Advice sought on specific measurement.
I did something similar a couple of years ago when type N "connector savers" were offered from China. These are male to female adapters. The first batch wasn't very useful about about 1.5 GHz. The second batch, from the same vendor were much better, working well to about 4 GHz. No idea why that was. They looked identical. I use APC-7 connectors, so your research is interesting to me.
Stuart K6YAZLos Angeles, USA
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-----Original Message----- From: Reginald Beardsley via Groups.Io <pulaskite@...> To: nanovna-users < [email protected]> Sent: Sun, Sep 22, 2019 8:25 am Subject: Re: [nanovna-users] Advice sought on specific measurement. I'm playing with rather more exotic HW, a Tek 11801 & SD-24 TDR head which is a ~26 ps rise time TDR evaluating the quality of Chinese RF connectors.? But the principles are the same and I'm very interested in using the nanoVNA for such things.? I'm a retired seismic research guy, so I've been having a blast. Most fun I've ever had with a piece of test gear and all I'm doing is playing. I look at the time domain S11 and the time domain S21 response.? The S11 TDR shows any discontinuities and the rise time of the S21 TDR gives me an estimate of the frequency limit.? In my case I'm putting the connectors between a couple of pieces of RG402 terminated with SMA-M connectors. If you do an SOLT on a short known high quality cable, then substitute the CUT and repeat the SOLT at the end of the CUT you should get a very accurate picture of cable and connector quality.? In the frequency domain there should be a linear phase shift difference between the reference cable and the CUT.? The ratio of the S21 values should give you the loss. I can't keep up with who's done what on this topic in the nanoVNA FW & SW, but the MATLAB clone, Octave is an ideal tool for taking data via the nanoVNA console and analyzing it.? The frequency spacing determines how long a cable you can test.? 1 MHz spacing will give you the ability to test to 100 m.? The resolution is dependent upon the maximum frequency. So 901 points from 1 to 900 MHz is probably a good choice of sweep parameters.? You'll need to use the reference cable results to compensate for amplitude errors in the nanoVNA.? If you pad lots of zeros on to the end of the frequency domain measurements you will get very fine sampling in the time domain. I recommend doing this with bare uncorrected data at least once using Octave just for the educational experience.? It's actually *very* simple.? And there are plenty of people here able to help out. I used? the 11801/SD-24 to test? another APC-7/N-F adapter yesterday from the same seller as in the photos here: Comments on second sample: I've still got tests of BNCs and other stuff to do with the 11801 and then I'll be duplicating some of the tests on the nanoVNA and my 8753B. Have Fun! Reg
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gin&pez@arg
Peter Mulhare
