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Bad nanovna?
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Hi all. I am new to this group. I recently bought a nanovna off Ebay. It's a black one, set up for 900MHz and 2 traces. It will not measure S21. All I get is noise at +/-10dB peak levels. S11 works just fine. Should all nanovna units be able to measure S21 regardless of being a "antenna analyzer" or "vector network analyzer". BTW, what is the difference? Of what value is the 4-trace version? I read that in order to flash a 4-trace firmware onto a 2-trace unit, the pgm needs to be unloaded? I tried upgrading the firmware, installing the boot-loader and I found 3 versions of firmware. The boot-loader seems to work fine, sees the device but when I try to load a firmware file, I get a message "not correct format" or something like that. Both softwares used for operating the unit work OK. Should I send this one back and buy a new one or have I not done something I should have? I am not a programmer. I would like to turn the switch on and use it. Thanks.
Ken |
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Bob Albert
My unit has developed a problem I can't solve.? It is intermittent.? Sometimes it works well but then it gives me a gratuitous reboot or shuts down and then isn't working.? I recalibrate a few times and it seems to recover for a while.
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I don't know what to do, other than scrap the unit and get another.? At the price, it's not all that painful.? I haven't tried it today but it's a crap shoot. Bob On Friday, October 4, 2019, 10:08:17 AM PDT, <hellhound604@...> wrote:
Have you calibrated it? If you connect a fly-lead between port 0 &1, what do you measure ? And a 3dB pad? |
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Yes, calibrated fine. S11 works fine. With a direct cable between the
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ports, I get the noise centered around 0dB. Removing the cable, the display is exactly the same. Inserting an attenuator, there is no change. On Fri, Oct 4, 2019 at 1:08 PM <hellhound604@...> wrote:
Have you calibrated it? If you connect a fly-lead between port 0 &1, what |
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Bob Albert
Yes it works sometimes.? The SWR display is particularly erratic.? But even when it works, it's only temporary until it decides to shut down.
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The unit hasn't been abused.? I am impressed when it works.? But then it stops. At one point a screw fell out of the little panel and I discovered they were all in various stages of looseness so I snugged them all up.? I doubt that affected anything. I tried the PC program to control it and it's more or less the same. Bob On Friday, October 4, 2019, 10:21:31 AM PDT, Ken Bozarth <kwbozarth@...> wrote:
Yes, calibrated fine. S11 works fine. With a direct cable between the ports, I get the noise centered around 0dB. Removing the cable, the display is exactly the same. Inserting an attenuator, there is no change. On Fri, Oct 4, 2019 at 1:08 PM <hellhound604@...> wrote: Have you calibrated it? If you connect a fly-lead between port 0 &1, what |
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Dry solder joint maybe? Saw some people had issues with the SMA-connectors
not soldered properly On Fri, 4 Oct 2019 at 19:32, Bob Albert via Groups.Io <bob91343= [email protected]> wrote: Yes it works sometimes. The SWR display is particularly erratic. But |
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Probably someone tried to measure amplifier with this nanovna and it's CH1 input is burned out. Another possible root of cause - incorrect channel setting for trace.
In order to check, do the following: 1) Open CAL menu and press RESET 2) Open DISPLAY - TRACE and select blue TRACE1, make sure it is enabled 3) return back to DISPLAY menu and open CHANNEL menu and select CH1 THROUGH 4) return back to DISPLAY menu and open FORMAT menu and select LOGMAG 5) try to connect/disconnect CH0 with CH1 with cable and check if blue trace has significant change if you performed these steps and blue trace does not respond on cable between CH0 and CH1, then your CH1 input doesn't works. |
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Bob Albert
I saw the comment regarding soldering of the connectors and checked mine, which look good.? I don't think the problem is mechanical, as I have tried gentle tapping and warping without effect.? Tightening the connectors makes no difference.? It smacks of the all too common spontaneous reboots that various computers exhibit at times.? Even the one I'm using now will freeze up once in a while.
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Bob On Friday, October 4, 2019, 10:34:43 AM PDT, Hendrik Fleming <hellhound604@...> wrote:
Dry solder joint maybe? Saw some people had issues with the SMA-connectors not soldered properly On Fri, 4 Oct 2019 at 19:32, Bob Albert via Groups.Io <bob91343= [email protected]> wrote: ? Yes it works sometimes.? The SWR display is particularly erratic.? But |
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I did what you suggested. Nothing change the CH1 display of noise. Bad
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unit, I guess. The seller does not respond. Thanks for your input. On Fri, Oct 4, 2019 at 1:40 PM <qrp.ddc@...> wrote:
Probably someone tried to measure amplifier with this nanovna and it's CH1 |
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Bob Albert
Yes blue trace responds properly.
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On Friday, October 4, 2019, 10:40:59 AM PDT, <qrp.ddc@...> wrote:
Probably someone tried to measure amplifier with this nanovna and it's CH1 input is burned out. Another possible root of cause - incorrect channel setting for trace. In order to check, do the following: 1) Open CAL menu and press RESET 2) Open DISPLAY - TRACE and select blue TRACE1, make sure it is enabled 3) return back to DISPLAY menu and open CHANNEL menu and select CH1 THROUGH 4) return back to DISPLAY menu and open FORMAT menu and select LOGMAG 5) try to connect/disconnect CH0 with CH1 with cable and check if blue trace has significant change if you performed these steps and blue trace does not respond on cable between CH0 and CH1, then your CH1 input doesn't works. |
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Ken,
The 2-trace, unshielded ports, black unit is usually delivered uncalibrated and is not useable out of the box. The following usually gets it going: First select "RESET" under the "CAL" menu and then perform the normal calibration procedure and save to location "0". On a Windows PC you need to select a firmware with the .dfu extension for use with the flash utility when upgrading your device. Herb |
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Bob,
If you are using the original firmware that came on your nanoVNA then the symptoms haven't been reported by other members and you may have a hardware problem. If you have upgraded your firmware then there is the possibility that the process did not take correctly and is causing your problems. Herb |
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Bob Albert
I just went through a calibration and save and it seems to be working correctly this morning.? Time will tell.
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I almost ordered another unit.? Apparently the prices have dropped significantly. Bob On Friday, October 4, 2019, 10:52:20 AM PDT, hwalker <herbwalker2476@...> wrote:
Ken, The 2-trace, unshielded ports, black unit is usually delivered uncalibrated and is not useable out of the box.? The following usually gets it going: First select "RESET" under the "CAL" menu and then perform the normal calibration procedure and save to location "0". On a Windows PC you need to select a firmware with the .dfu extension for use with the flash utility when upgrading your device. Herb |
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Thanks. I did all that, still no S21. I think it's blown up. There is also
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an incompatibility between the firmware files I found and the SGMicro bootloader pgm. It was listed as "new out of box" and the protective screen plastic has lots of marks on it, though the unit was sealed. Anyone can seal those plastic envelopes. Now the seller has nothing to sell and does not respond. On Fri, Oct 4, 2019 at 1:52 PM hwalker <herbwalker2476@...> wrote:
Ken, |
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