Re: RX-Port Input Impedance
yes, my NanoVNA CH1 also has VSWR=1.3 at 900 MHz. You can measure it by connect CH0 to CH1 with a good quality and short cable.
Also, according to my CH0 output voltage measurement, the output impedance of CH0 is about 39 Ohm. But it may be not very precise, because I measured it with 100 MHz bandwidth oscilloscope.
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Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
Dr. David Kirkby from Kirkby Microwave Ltd
On Fri, 20 Sep 2019 at 03:52, bryburns via Groups.Io <bryburns= [email protected]> wrote: When a VNA is connected to an antenna (often they are outdoors) there are
some potential issues with electrostatic discharge (ESD.) In dry areas of
the world ESD can be an issue even when working with objects that are
purely indoors. I have seen issues when working on tables indoors. Other
VNA devices are known to have issues. Does anyone know how sensitive the
RF inputs to the nanovna are with regard to ESD? Is there any ESD
protection built into the RF connections on the nanovna?
--
Bryan, WA5VAH 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. Here¡¯s a video from dave Jones of EEVBLOG measuring the DC resistance of antistatic mats. Two DVM probes are put next to each other, the meter, which can read upto 300 M ohm can measure anything. What is more an issue is having the NanoVNA connected to an antenna in the presence of another transmitter locally. But that¡¯s another issue thing altogether 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: Does anyone know how sensitive the nanovna is to electrostatic discharge?
On Sun, Sep 22, 2019 at 03:26 AM, <bryburns@...> wrote:
I would think that the current will be even less when we apply ~-10 dBm or 0.1
v pk signals to it. 0.1 v is approximately 35 dB smaller than 6 V.
As I know there is no diode in the world that can protect wide bandwidth RF input with no dynamic range degradation and no IMD distortions. Otherwise it will be used in a wide range of sensitive RF equipment. Usually low flicker noise high speed Schottky diodes are used for such purpose, for example HSMS2812 or something like that. But they also reduce dynamic range of the signal. As for voltage suppressors, once I tried 82V voltage suppressor for 10V transmission line, but it has so high IMD distortion, so digital signal completely unreadable. PS: as for NanoVNA output level, it has peak output about 324 mVpp on 1 MOhm/18 pF load. Such level can open some diodes
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Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
If you want to try out the GB1010603 devices, they are available on eBay as item?111468959425. The price for ten shipped in the USA is?$4.85. I am not associated with the seller.?They should be very effective in protecting sensitive RF devices and equipment. These devices are are surface mount, size 603.
Stuart K6YAZLos Angeles, USA
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Show quoted text
-----Original Message----- From: bryburns via Groups.Io <bryburns@...> To: nanovna-users < [email protected]> Sent: Sat, Sep 21, 2019 5:26 pm Subject: Re: [nanovna-users] Does anyone know how sensitive the nanovna is to electrostatic discharge? qrp.ddc Thanks for your reply.? I agree it would be very detrimental to the our measurements to put a diode in place that has 10-15 pF of capacitance. I would never recommend that. Apparently you did not look at the data sheet for the PGB1010603 device I attached above.? I did not assume it was 0.06 pf.? On page 1 of the data sheet the measured capacitance for the device is 0.06 pf when measured at 250 MHz.? At that frequency this corresponds to a reactance of a little over 10,000 ohms.? Surely this won't have much impact on measurements in a 50 ohm system at that frequency.? Therefore, it appears that this device is substantially different from those with which you are familiar. I agree we should not use typical voltage suppressor diodes to protect the input to VNA devices.? They produce large non-linearities which can really screw up measurements. Please follow my thinking for a minute.? The first page of the data sheet for the device says that the "leakage" current through the device will be less than 1 nano amp at 6 volts.? I would think that the current will be even less when we apply ~-10 dBm or 0.1 v pk signals to it.? 0.1 v is approximately 35 dB smaller than 6 V.? But, let's assume it is still 1 nano amp. This corresponds to a power level of about -100 dBw or -70 dBm peak power.? This is approximately 60 dB below the signal being applied to the circuit we are testing.? This still seems like a very low power in the diode for creating mixing products.? I don't think any mixing products can be larger than this amplitude, in fact, I think they have to be smaller. Perhaps I did not ask my question above regarding assumptions clearly.? I am not an expert on how VNA calibration works.? I hope you are.? If there is variation in stray capacitance on the VNA input of a fraction of a pF for any reason (manufacturing tolerances, component variations, etc.), will the OSLT calibration we commonly use with devices such as nanovna compensate for it in our measurements after calibration?? Is some other action required on my part?? I thought this is one of the very purposes of OSLT calibration in all VNAs. -- Bryan, WA5VAH
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Re: New owner of the Nano VNA
William,
The nanoVNA can easily perform the VSWR measurements you bought it for, but because it can do so much more you are going to have to invest some time and study learning its operation and menu structure. You might start out with this link, . Pay special attention to the calibration procedure. Without a properly calibrated unit your test results will make you want to give up on using the nanoVNA pretty quickly. On the left hand side of this groups page are some excellent resources, in particular ensure you browse through the "Files" and "Wiki" sections. The members of this group are more helpful and knowledgeable than any I've joined in the past. The total messages are already up to 2821 in the relatively short time the group has been formed. Reading through all the messages is an education in itself. Welcome to the party.
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Re: New owner of the Nano VNA
Also, how do I use this on my PC? I've downloaded the software but can't seem to be able to figure out what to do next.
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New owner of the Nano VNA
I received my little gadget today. I'm not familiar with this type equipment and am trying to figure how to use it. I've watched a video on line and got a little info on it. I've run a test on my OCF wire antenna getting the SWR readings. I'm not certain I got accurate readings as they don't compare with the readings my radio shows. Can anyone help guide me through how to check my SWRs? Maybe later I'll try learning other things I can use this for. Thanks for any help.
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Using nanoVNA to measure the directivity of a directional coupler
Here is another application for nanoVNA.
I own a Narda 3060-20 directional coupler that I have not been able to find directivity information on. The coupler has a 10-200 MHz frequency range and a -20 dB coupling factor. The test setup photo is attached.
Test procedure:
1. Connect nanoVNA CH0 to the output port of the coupler under test.
2. Connect nanoVNA CH1 to the coupling port of the coupler under test.
3. Leave the input port of the coupler under test open.
4. Turn on the nanoVNA
5. Set the nanoVNA to display CH1 LOGMAG only to reduce screen clutter.
6. Set the start and stop frequencies of the nanoVNA as appropriate for the coupler.
7. In the nanoVNA CAL menu select "RESET" and then select "Calibrate-Thru" and "Done".
8. Back out of the menu to the main CH1 LOGMAG display (Should be a straight line at 0 dB, see photo 1).
9. Connect a 50 ohm load to the input port of the coupler under test.
10. Use the marker to read the coupler directivity off the displayed response (see photo 2).
The measured directivity of the Narda 3060-20 was 30 dB at 10 MHz and 22.5 dB at 200 MHz. The minimum directivity for a reliable measurement is 20dB, and 30dB or larger for the measurement of well-matched devices. Hope this info is useful to other nanoVNA users.
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Re: Yet another NanoVNA PC app
Don't complain about the manual, it is being adapted but not done yet DOCX was converted to markdown using pandoc, then hacked and posted to GitHub: This markdown has yet to incorporate nanoVNA content; pull requests are welcome.. Wiki now includes links to this and Tapr-VNA code: /g/nanovna-users/wiki/home
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Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
qrp.ddc
Thanks for your reply. I agree it would be very detrimental to the our measurements to put a diode in place that has 10-15 pF of capacitance. I would never recommend that.
Apparently you did not look at the data sheet for the PGB1010603 device I attached above. I did not assume it was 0.06 pf. On page 1 of the data sheet the measured capacitance for the device is 0.06 pf when measured at 250 MHz. At that frequency this corresponds to a reactance of a little over 10,000 ohms. Surely this won't have much impact on measurements in a 50 ohm system at that frequency. Therefore, it appears that this device is substantially different from those with which you are familiar.
I agree we should not use typical voltage suppressor diodes to protect the input to VNA devices. They produce large non-linearities which can really screw up measurements.
Please follow my thinking for a minute. The first page of the data sheet for the device says that the "leakage" current through the device will be less than 1 nano amp at 6 volts. I would think that the current will be even less when we apply ~-10 dBm or 0.1 v pk signals to it. 0.1 v is approximately 35 dB smaller than 6 V. But, let's assume it is still 1 nano amp. This corresponds to a power level of about -100 dBw or -70 dBm peak power. This is approximately 60 dB below the signal being applied to the circuit we are testing. This still seems like a very low power in the diode for creating mixing products. I don't think any mixing products can be larger than this amplitude, in fact, I think they have to be smaller.
Perhaps I did not ask my question above regarding assumptions clearly. I am not an expert on how VNA calibration works. I hope you are. If there is variation in stray capacitance on the VNA input of a fraction of a pF for any reason (manufacturing tolerances, component variations, etc.), will the OSLT calibration we commonly use with devices such as nanovna compensate for it in our measurements after calibration? Is some other action required on my part? I thought this is one of the very purposes of OSLT calibration in all VNAs.
--
Bryan, WA5VAH
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0.0.10a is Rune's pre-release at . This is the location for his latest commits prior to final release as executable.
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hwalker,
Where do you find NanoVNA Saver 0.0.10a.exe ? I went here: and see 0.0.10 but not 0.0.10a. Would love to have the whole screen fit in my 1366X768 screen.
Rune,
Thank you so much for fitting the whole screen into a 1366x768 screen. That will really make the NanoVNA Saver software so much easier to use.
Thanks,
Steve_WB8GRS
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Maurizio,
Rune's latest commit 0.0.0a adds an averaging option. Check it out and let him know what you think.
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Hi , I found some info about the smoothing and average on Keysight network analyzer at this link :
Best regards
Maurizio
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Re: How to read out my NanoVNA's firmware version
Hello tinhead,
Thank you very much about the hint with the terminal, to ask about the nanoVNA version.
I did not know that.
As you can see in the attached screenshot, the "version" command answer is *empty*.
I am using Erik's nanoVNA version with "scan" command and upper frequency of 1500 MHz.
It would be nice to read that out, because, at least for me, after a few weeks you (me) no longer remembers
which version was flashed.
It should be not too difficult for Erik to edit file ui.c in function show_version(void) (line 387)
the VERSION text e.g. "0.1.1 + scan 1500MHz".
73, Rudi DL5FA
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Re: NanoVna Menu Scroll Switch Repair Replacement?
Thanks Larry
I will pull it apart and have a look. regardless if the replacement switch is sent I will replace the switch with SMT switches as in your mod.
Andy "thats buying from China" As the saying goes buy the first model for your enemy, the second for your friend and the 3rd for yourself. But you dont even have these options from China since these units I believe are bulk manufactured and are mostly distrubuted by anyone and anything. I dont know why Ebay allows these people to tell lies when stating they in your home country when they clearly shipping from China.
Thanks all
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Rune,
I just checked out your Latest commit, 0.0.10a and loving the fact that on my 1366x768 display I can see the whole screen without needing scrollbars. All the charts size very nicely at font size 7, even with show data turned. I think the pop up windows for Files, Calibration, Display setup, and About are nicely thought out. I wish at some point in the future you could add a setting under "Display setup" that would allow the user to add a centered caption at the top of the graphs for documentation purposes. Keep up the great work!
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Re: Comparing antenna gain process
On Sat, Sep 21, 2019 at 09:46 PM, Ken Buscho wrote: Any special calibration considerations to minimize other signals coming in? If
I don't have a test device hooked up, whatever Ref sees is outside world, can
it be calibrated or filtered out someway? Use the zero span option. That way the display only reports your "channel" I think that would work. 73 de Andy
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Rune,
Thanks for all of your work on this. I know from personal experience the effort and dedication that something like this requires. When I bought my NanoVNA, I had no idea that I was "surfing" the early adopters wave. I am a recently retired electrical engineer and the intellectual stimulation has been welcome, especially when dealing with a well designed software application like yours. The "bleeding edge" apps are not always this well thought out. It is quickly getting to the point where the first digit of the version number can be an integer greater than zero.
I do have a suggestion....
I have a 4k UHD monitor and one of the issues that I have is that most apps use fonts that have a single pixel stroke width which can be quite hard to read. I know that you have a font size option, which helps, however, I found that simply going to the Bold version of a font can widen the font stroke width and make big improvements in readability on a UHD monitor without changing the font size. Perhaps, you could put this option on your to do list for a future version.
73
Logan, KE7AZ
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Re: Comparing antenna gain process
Warren,
Thanks for the kudos, I always try to figure out a way to find new uses for existing things, Sadly, these ideas usually pop in when my mind is idling right before bedtime, and then I'm up for another hour or two testing it out. Sleep is overrated, that's why they invented coffee
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Oristo
KE7AZ