开云体育

Hi everyone and thanks for letting me join the group.

My new NanoVNA H4 arrived today, and I had high hopes for it but it appears to be faulty. I already have another VNA so I have a reasonable understanding of the concepts involved.
I did a calibration on the unit using the supplied cal kit and it all seemed to go well. However, when I create a trace with R or X, and try to measure a 50 ohm load, I get all sorts of erratic readings (3 milli ohm etc) and a flat line on the screen.
I have measured the cal load supplied, and it measures around 49.8 ohm. I have also tried the cal procedure a few times and tried measuring another 50 ohm load but always the same erratic readings - close to 0 ohms.
I have also checked the output on port CH0 and there is a nice RF sweep visible on a CRO.

The VNA is running version 0.5.0 and the Kernel is 5.1.0.

Has anyone come across something similar, and is it likely that updating the firmware would help?

Cheers,
Peter - VK2AN

Hello Peter,
I'm not sure I think so - but it's worth a try.
Please remove the touch screen cover You need to remove or loosen 4 screws and try to test. It is possible that there are still -H4 left in the initial production where this was the cause of the problem. The reason is that the lid is partially pressed against the touch screen, which confuses it.

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Gyula HA3HZ

Ps: If this improves, you may want to install the latest version, because the computer programs are designed for it. Pay attention to the exact name (NanoVNA-H4). I think the fw. v1.1.0 and NanoVNA-App v 1.0.209. Either read the forum / wiki or go to my website for more information. link:

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Gyula HA3HZ

Hi Gyula,

I have removed the screen cover as suggested and it is certainly much more responsive now. I have also set it to Smith chart and the readings appear correct, after some further investigation it appears I was getting funny readings on SWR because the marker was set at 10Khz but the range I was looking at was much higher.

It certainly will be a very useful little box to have when out in the field or in the car - very impressed with it so far. It does seem to leave bits of graph on the screen occasionally when the display is changing - I will take your advice and attempt to upgrade the firmware.

Thanks for your help, and I hope the situation in Ukraine improves - I have some relatives in HU and they are very worried.

Cheers,
Peter - VK2AN
________________________________
From: [email protected] <[email protected]> on behalf of HA3HZ <gyula@...>
Sent: Wednesday, 23 March 2022 7:16 PM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] Need advice on a NanoVNA fault

Ps: If this improves, you may want to install the latest version, because the computer programs are designed for it. Pay attention to the exact name (NanoVNA-H4). I think the fw. v1.1.0 and NanoVNA-App v 1.0.209. Either read the forum / wiki or go to my website for more information. link:

--
Gyula HA3HZ

When I purchased -H4 from the first shipment, I ran into this error. The solution for me was to look for 4 pieces of plastic pads that I placed between the pcb and the lid (you can fix it with a drop of glue so it wouldn’t move), so I lifted the lid and didn’t push the touch screen.
I'm glad you fixed the error.
A useful little structure that makes visible what we’ve just talked about so far. :-) I wish you a successful use.

To live and let live, this is forgotten by those who want to rule.
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Gyula HA3HZ

1/have you a copy of your soft ware 5.1.0
you need to look at bottom for plastic stuch under cove
this caught me out