YO3GGX Projects Forum

Hello,

I am referring to the App MetroVNA. Is this the right place for it?

At the beginning I want to thank you for this nice Software!
But I have one complain: in Transmission-Mode the reading of this software is very inaccurate! A 20dB-Attenuator shows only about -14,7dB.

73 de Uwe, DL4AC

Hi Uwe.

MetroVNA is just a fork from an older version of BlueVNA application. In the current version of BlueVNA you can select the DDS frequency so you can use it with MetroVNA too.

Please check if with the latest version of BlueVNA you have the same issue.

Thank you.
73 Dan YO3GGX

Hi Dan,

thank you very much for your help!

I just tested BlueVNA and it runs with my MetroVNA. I selected "MiniVNA" and in Reflection-Mode it is quite accurate. But in Transmission-Mode I get wrong readings with BlueVNA, as well.
For example with 10dB Attenuation I get a reading of -6,4dB; at 20dB I get -14,7 and at 30dB I get -23,2dB; at 40dB I get -31,5dB; at 50dB I get -39.2.
So I think that there is a difference between MiniVNA and MetroVNA!? I think the coefficient of calculating TL must be changed...

73 de Uwe, DL4AC

Hi Uwe,

I'm not aware of any difference in Transmission mode between miniVNA standard and MetroVNA.
Did you done a transmission calibration first (open and loop)?

73 Dan YO3GGX

Hi Dan,

yes, I performed an open- and a loop-calibration. And yes, there is a difference between the MiniVNA and the MetroVNA in TL! I think that the dynamic of the MetroVNA is a little bit higher. I observerved the same behavoir in VNA/J and Dietmar modified the TL-Parameter for MetroVNA. He will asap offer a new version.

I wonder, if the CABLE-Measurement should work with the MetroVNA? I tried it with cables of 2 to 4m and BlueVNA can't calculate the length. After two passes of calculation the "?" is still there.

73 de Uwe, DL4AC

Hi Uwe,

I will try to contact Antonio and see if he can help with more details on how to make BlueVNA compatible with MetroVNA in transmission and cable modes. I'll be back as soon as I will have an answer.
My intention is to unify all the versions and to keep just BleVNA and add an autodiscover functionality in order to autodetect the VNA model.

Thank you.
73 Dan YO3GGX

Hi Dan,

thank you very much for your info and for your engagement!!!!

73 de Uwe, DL4AC