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NanoVNA V2plus 4 Problems in Low-Frequency Narrowband Measurement


Tenko46T 2020/11/28 04:53

Hello, everyone

Yesterday I received NanoVNA V2plus4 from DHL which I was looking forward to. Unfortunately, when I measured the 10.7 MHz monolithic crystal filter S21, there was an abnormality in the waveform, so I would like to report it. Attach the same filter results as measured with V2_2 and V2plus4. The waveform of V2plus4 is jagged and not smooth. This does not happen with V2_2, so I think it is the problem of the V2plus4 which I purchased. This phenomenon appears to be frequency dependent and did not occur with the 20 MHz crystal S21. I tried making and replacing the latest version of the git -20201124 firmware, but it was still the same. Waveform errors are the same for stand-alone operation or controlled by NanoVNA-App v 1.1.160 via USB.
I hope this problem will be resolved.
--
TENKO

Siegfried Jackstien 2020/11/28 17:24

Calibrate and measure your xtal filter with x5 average.. Then calibration has
less "noise" and also the measurment at the end is more exact

Greetz sigi dg9bfc



Am 28.11.2020 13:53 schrieb Tenko46T <nasa46vb@gmail.com>:

> Hello, everyone

>

>
>

> Yesterday I received NanoVNA V2plus4 from DHL which I was looking forward
to. Unfortunately, when I measured the 10.7 MHz monolithic crystal filter S21,
there was an abnormality in the waveform, so I would like to report it. Attach
the same filter results as measured with V2_2 and V2plus4. The waveform of
V2plus4 is jagged and not smooth. This does not happen with V2_2, so I think
it is the problem of the V2plus4 which I purchased. This phenomenon appears to
be frequency dependent and did not occur with the 20 MHz crystal S21. I tried
making and replacing the latest version of the git -20201124 firmware, but it
was still the same. Waveform errors are the same for stand-alone operation or
controlled by NanoVNA-App v 1.1.160 via USB.

>

> I hope this problem will be resolved.

>

> \--
> TENKO



_._,_._,_

* * *

Tenko46T 2020/11/28 14:41

​Thank you for your reply.

​As you told me, I calibrated and measured again using x5 averaging operations.

​Unfortunately, the results remained the same jagged and no improvement.

​As a separate experiment, I tried smoothing the trace, but it appears to improve the waveform smoothly but does not provide a fundamental solution because it reduces the fidelity of detail. ​

By the way, this thread is a double post to make up for missing the image attachment in the previous article. ​I am very sorry, but I would like to close this thread.
--
TENKO

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