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New NanoVNA V2_2 is defect above 140 MHz

hermann.straatmann 2021/01/08 13:31

Hallo members, I'm very new here,
because mid December I bought a new NanoVNA V2_2 on ebay Germany to do measurements at marine-2-meter-equipments on several sailing boats.
For version, please see picture.
After first starting, device was defect up frequency 140 MHz. In that range above all traces are going undefined, with or without calibration, with or without DUT - no difference.
For example see picture, 85-170 MHz, calibrated, 2-m-rod-antenna on port 1 -smith trace off, to see more clearly. In reality traces are swinging and changing every sweep.
Seller send my money back and didn't want the device back, because it's in the status of electronic trash, economical total loss.
I will buy another one, but not yet sure where to do.
Now further interested I checked the NanoVNA inside: No fails to see. Device software works correctly, USB to PC  too in tested menues. Only measurements aren't going on because all traces undefined.
Can anyone help me to identify the bug?
May be one or both of the ADF 4350 Synthesizer doing the range up to 140 MHz?

OwO 2021/01/09 12:59

Check the two blue LEDs under the board near the ADF4350 synthesizers.
These indicate PLL lock.

On 09/01/2021 05:31, wrote:

hermann.straatmann 2021/01/09 06:15

Thank you OwO for answer.
Blue LED 401 is continously on - seems ok.
Blue LED 601 is blinking in phase the sweep - seems uncorrectly.

hermann.straatmann 2021/01/11 12:14

May it be possible to localisate bug in or round unlocked ADF 4350 with very small equipment?

Siegfried Jackstien 2021/01/11 21:18


Am 11.01.2021 21:14 schrieb

> May it be possible to localisate bug in or round unlocked ADF 4350 with very
small equipment?


* * *

gclarkii 2021/01/11 17:43

Could having a VERY old version of the firmware cause this kind of problem?
Your firmware 20200308(which I guess is really 20200328 in disguise looking at the compile date) was the first production release.

Concerning your last question, considering that the 20200619 firmware included changes to turn off the ADF4350 if the sweep was below 140 MHz, I would say it's a distinct possibility.

Using NanoVNA-QT made upgrading a breeze for me(I've got one of the clones, the 3.2" "Black and Gold").
Their website has all the information needed to do the upgrade.

Hermann Straatmann 2021/01/12 07:37

Thank you gclark for answering. I already found the difference in firmware
datings too, but thought there is no reason.
One of the two ADF 4350 doing frepuency above 140 MHz doesn‘t lock pll. So
I‘am searching problem in hardware.
Now I first will test your idea.

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