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Hi Rudi

First of all the use of the testcables from the NanoVNA female SMA adaptor (the SMA male female adaptor saver) to the reference plane is a bad idea. The female female adaptor used during calibration has loss and has influence on the sweep of the semirigid cable sweep so the sweep run outside the Smith chart. Adding the female female adaptor at the end of the semirigid cable is also wrong as the loss in the female female adaptor again creates a wrong trace around the Smithchart. The female female adaptor supplied with the NanoVNA has in particular high loss and any other female female adaptor has some loss to account for.
So do the following:

Directly at the VNA SMA female Ch0 adaptor do a S11 calibration (do not use the supplied open adaptor) and connect you semirigid cable directly afterwards and leave the far end unterminated. Ideally the semirigid cable should end blindly but the SMA male adaptor has little effect loss wise, but it is there despite small and hardly detectable. The big bug is the female female adaptor you must not connect as you did.
When dealing with the N calibration kit then use a SMA male to N female adaptor and at first directly connected to the NanoVNA Ch0 female adaptor. Afterward you may experiment with adding test cables and do the calibration from there where you are forced to use the female female adaptor or better a SMA female to N female adaptor.

Use the NanoVNA saver feature to save the first sweep directly on Ch0 to "Save as Reference" as you then can compare step by step what you are doing.

Do not expect the NanoVNA to beat a more advanced VNA, it still has some shortcoming and you got a version which is characterized by some as a bad clone ?

Kind regards

Kurt



-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af reuterr@...
Sendt: 20. oktober 2019 10:02
Til: [email protected]
Emne: Re: [nanovna-users] The Male Calibration Kit for AliExpress



Hello Kurt,

Thank you very much for taking care about my question.

I will write my answers below your questions.



On Sat, Oct 19, 2019 at 10:56 PM, Kurt Poulsen wrote:

1. Did you use a male SMA to N female adaptor directly fitted to the

SMA

No.

female adaptor for Ch0 ?

Just a male-female thread saver, as could be seen on the photo.

2. Did you before using the NanoVNAuser ensure the NanoVNA was

correctly calibrated directely at the NanoVNA Ch0 female adaptor with

the supplied calibration kit ?

The nanoVNA was calibrated at the *Reference Plane* shown in the photo.

The used *Calibration Kit* was the supplied one.

The *Open* SMA part was replaced with a *female-female adapter*.

2a. and did a sweep of a 25 to 50cm SMA test cable show better result?

I can not understand the question.

3. The test cable is probably too long and shall be a N type cable

with no adaptors fitted

I do not have that.

4. Your NanoVNA has a poor bridge as NanoVNA as far as I know has no

internal error correction

I measured the 50 Ohm resistance with a 3 VDC supply and a 4 digit *Ampere meter* and *Volt meter* The nanoVNA CH0 port shows 49.23 Ohm.

The 50 Ohm load shows 50.72 Ohm.

A self made 50 Ohm load from 2 SMD 0805 100 Ohm 1% resistors in parallel shows 49.99 Ohm (interesting).

There is probably more reasons and it would be better if you explained

in details you setup

Please see the attached photo: nanoVNA_50cm-RG402-open2_f-f_DSC08152.jpg

I have attached 2 screen captures from nanoVNA-saver with the S11 measured 50 cm RG402 coax cable.

nanVNA-Saver_50cm-RG402-open2.png - End of RG402 SMA male plug open nanoVNA-saver_50cm-RG402-open2_f-f.png - End of RG402 male plug with *female-female adapter* It is interesting how much the *Parallel X* capacity changed.



The nanoVNA-saver has an additional calibration with 5 segments.



What can I enter in the window Calibration->Calibration standards in order to improve the measurement?

73, Rudi DL5FA