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Defective NanoVna

 

I just received a NanoVna from Amazon (AURSINC). It is a black one with the shields.

The receive side shows a signal at 300 MHz with input connected to dummy load. The signal is so strong that it shows at -6 dB from the top of the screen. I have two others that are from other sources and they show a very small signal at around 300 MHz that does not interfere with measurements.

The interference on this one is so bad that it is unusable.

Any idea what this could be and is it something I can fix without returning it to Amazon? Tried calibration and it did not help.

Any help greatly appreciated.

Jim K.

Bad_Spur_at_300 MHz.jpg

 

Hello,

Have you tried to upgrade (firmware) your unit?

That issue was already addressed.

Cheers!

LL

On Tue, 6 Aug 2019 at 21:18, <jimcking@...> wrote:

I just received a NanoVna from Amazon (AURSINC). It is a black one with
the shields.

The receive side shows a signal at 300 MHz with input connected to dummy
load. The signal is so strong that it shows at -6 dB from the top of the
screen. I have two others that are from other sources and they show a very
small signal at around 300 MHz that does not interfere with measurements.

The interference on this one is so bad that it is unusable.

Any idea what this could be and is it something I can fix without
returning it to Amazon? Tried calibration and it did not help.

Any help greatly appreciated.

Jim K.
 

Yes, I did reload firmware with nanoVNA_900ch_20190722.dfu

Forgot to mention that earlier. The above firmware did help on one I got earlier with a lot lower spike but did not help much on this one.

Thanks for the help though.

Jim K.
 

OK, so please try the 800Mhz version.

Its used for high temp. Will also eliminate some harmonics. Hope
it helps... There is a August version already.

Cheers!

On Tue, 6 Aug 2019 at 22:14, <jimcking@...> wrote:

Yes, I did reload firmware with nanoVNA_900ch_20190722.dfu

Forgot to mention that earlier. The above firmware did help on one I got
earlier with a lot lower spike but did not help much on this one.

Thanks for the help though.

Jim K.
 

Hi Jim

The 800MHz versions of the firmware are the ones that avoid glitches at 300
and/or 600MHz.

The design seems to be based on pushing chips beyind spec and using
harmonics of the oscillator signal for higher frequencies - I assume the
changeover points are 300 & 600 MHz with the 900 MHz builds.

Mike

On Tue, 6 Aug 2019, 22:14 , <jimcking@...> wrote:

Yes, I did reload firmware with nanoVNA_900ch_20190722.dfu

Forgot to mention that earlier. The above firmware did help on one I got
earlier with a lot lower spike but did not help much on this one.

Thanks for the help though.

Jim K.
 

Hi Mike,

Thanks very much for that information. The 800 MHz aa version of the firmware corrected the problem. The 800 MHz ch version did not. In fact the 880 MHz ch version still goes out to 900 MHz. I got the firmware from
Is there a newer version somewhere?

Thanks,

Jim K.
 

Hi SPACE OPQA,

Thanks for the info. Where is the August Version?

Thanks,

Jim K.
 

Hi Jim

I think we're all struggling to identify and track the different versions
of the firmware. I suspect they're all ones written by Hugen who wrote them
for the version he sells at gen111.taobao.com and now on Alibaba (search
his posts for a link).

Mike

On Wed, 7 Aug 2019, 09:53 , <jimcking@...> wrote:

Hi Mike,

Thanks very much for that information. The 800 MHz aa version of the
firmware corrected the problem. The 800 MHz ch version did not. In fact
the 880 MHz ch version still goes out to 900 MHz. I got the firmware from

Is there a newer version somewhere?

Thanks,

Jim K.
 

Hi,

Please check here:


[image: image.png]

On Wed, 7 Aug 2019 at 09:57, <jimcking@...> wrote:

Hi SPACE OPQA,

Thanks for the info. Where is the August Version?

Thanks,

Jim K.



image.png

 

Got it. Thanks. The 800 MHz ch now shows going to 800 MHz. It has another issue though. Spikes are all over and go all the way to the top of the screen when no load is attached. Looks OK with 50 Ohm load.

Jim K.
 

For every upgrade you need to calibrate it.

Before any calibration, you need to reset the calibration data.

Once saving the calibration to position 0 (zero) it will always load that
calibration data.

Turn off and on your unit after calibration.

Have a go and let us know!

Cheers

Lu¨ªs CT2FZI

On Wed, 7 Aug 2019 at 11:09, <jimcking@...> wrote:

Got it. Thanks. The 800 MHz ch now shows going to 800 MHz. It has
another issue though. Spikes are all over and go all the way to the top of
the screen when no load is attached. Looks OK with 50 Ohm load.

Jim K.
 

Did do a calibration right after the upgrade and save it to position 0 (zero). It shows the problem with or without a calibration.

Eventually figured it out and got it working. Apparently the new Aug 2 firmware does not actually change the frequency limit. It just leaves it at what is was (800 or 900 MHz)

The only firmware that seems to be able to actually change the 900 MHz limit to 800 MHz is the older June 22 firmware (nanoVNA_800_aa_20190722.dfu)

Once the older software sets the limit to 800 MHz, the new Aug 2 firmware ch with change it to 4 channels and leaves it at 800 MHz.

The new Aug 2 firmware ch also leaves the user area in a state of disarray such that it will actually crash. It was the phase display that was causing all the spikes. Finally managed to get the user area set up from the front panel. It is working great now on 800 MHz 4 channel.

Thanks for all you help,

Jim K.
 

Glad we could help!

73

On Wed, 7 Aug 2019 at 16:27, <jimcking@...> wrote:

Did do a calibration right after the upgrade and save it to position 0
(zero). It shows the problem with or without a calibration.

Eventually figured it out and got it working. Apparently the new Aug 2
firmware does not actually change the frequency limit. It just leaves it
at what is was (800 or 900 MHz)

The only firmware that seems to be able to actually change the 900 MHz
limit to 800 MHz is the older June 22 firmware
(nanoVNA_800_aa_20190722.dfu)

Once the older software sets the limit to 800 MHz, the new Aug 2 firmware
ch with change it to 4 channels and leaves it at 800 MHz.

The new Aug 2 firmware ch also leaves the user area in a state of disarray
such that it will actually crash. It was the phase display that was
causing all the spikes. Finally managed to get the user area set up from
the front panel. It is working great now on 800 MHz 4 channel.

Thanks for all you help,

Jim K.

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