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Performance of my nanovna V2 clone - return loss of port 2 seems much too high ?


Peter Ide-Kostic <on7yi.pik973@...>
 

Hello,

I bought a nanovna V2 <https://nanorfe.com/nanovna-v2.html> on Aliexpress a
while ago. When I received it, I realized that it was a clone which I did
not expect, but ok, I managed (as usual)

I then checked the performance vis a vis of the official nanovna-v2
specifications <https://nanorfe.com/nanovna-v2.html#specifications> .
Fortunately, on the positive side, there was no problem regarding the S21
dynamic range and regarding the S11 noise floor that both met the nanovna
V2 specifications. However I was a bit puzzled to discover that the return
loss of port 2 of my clone was unfortunately much higher than what is
officially specified....

official return loss specifications for port 2
20dB at 1.5 Ghz, 13 dB at 3 ghz

my measurements after calibration (see picture)
15.7 dB at 1.5 Ghz and 9.5 dB at 3Ghz

I wondering if
- I am doing something wrong the way I did this measurement
- if I am the only owner of a clone with this specific performance problem
on port 2
- if owners of the genuine nanovna V2 also have the performance issue
- what is the value of the attenuator that you possibly use on port 2
during calibration to compensate for the sub-optimal return loss (I use
between 6 and 12dB depending on the accuracy I need and the dynamic range I
am willing to sacrifice)

Thanks for sharing your return on experience regarding this issue

[image: image.png]


CT2FZI
 

Did you calibrate from 1.4GHz to 1.6GHz and tried to measure it again?

Did you tried using another cable?

Why you say it's a clone?

Cheers

A domingo, 16/08/2020, 21:48, Peter Ide-Kostic <on7yi.pik973@...>
escreveu:

Hello,

I bought a nanovna V2 <https://nanorfe.com/nanovna-v2.html> on Aliexpress
a
while ago. When I received it, I realized that it was a clone which I did
not expect, but ok, I managed (as usual)

I then checked the performance vis a vis of the official nanovna-v2
specifications <https://nanorfe.com/nanovna-v2.html#specifications> .
Fortunately, on the positive side, there was no problem regarding the S21
dynamic range and regarding the S11 noise floor that both met the nanovna
V2 specifications. However I was a bit puzzled to discover that the return
loss of port 2 of my clone was unfortunately much higher than what is
officially specified....

official return loss specifications for port 2
20dB at 1.5 Ghz, 13 dB at 3 ghz

my measurements after calibration (see picture)
15.7 dB at 1.5 Ghz and 9.5 dB at 3Ghz

I wondering if
- I am doing something wrong the way I did this measurement
- if I am the only owner of a clone with this specific performance problem
on port 2
- if owners of the genuine nanovna V2 also have the performance issue
- what is the value of the attenuator that you possibly use on port 2
during calibration to compensate for the sub-optimal return loss (I use
between 6 and 12dB depending on the accuracy I need and the dynamic range I
am willing to sacrifice)

Thanks for sharing your return on experience regarding this issue

[image: image.png]




Peter Ide-Kostic <on7yi.pik973@...>
 

Thank you for your reply

1) Please find below the trace between 1.4 and 1.6 ghz, of course there no
change (as expected)

[image: image.png]
2) The cables are fine I am sure, they are quality SS405 cables of 25 cm

3) To make a long story short, it is the owner of the Aliexpress shop
himself who informed me that he could no longer deliver the genuine model
<https://nanorfe.com/nanovna-v2.html#> that I had initially ordered in the
April time frame as he had switched supplier. I do not want to enter into
details but I was quite lucky with this specific transaction on aliexpress,
I waited a very long time (with at least 3 different shipping attempts) .
When the device finalmly arrived it had been damaged by transport . The
seller then simply offered me to send me the models coming from his new
supplier which I have accepted.

On Sun, Aug 16, 2020 at 10:55 PM CT2FZI <ct2fzi@...> wrote:

Did you calibrate from 1.4GHz to 1.6GHz and tried to measure it again?

Did you tried using another cable?

Why you say it's a clone?

Cheers

A domingo, 16/08/2020, 21:48, Peter Ide-Kostic <on7yi.pik973@...>
escreveu:

Hello,

I bought a nanovna V2 <https://nanorfe.com/nanovna-v2.html> on
Aliexpress
a
while ago. When I received it, I realized that it was a clone which I
did
not expect, but ok, I managed (as usual)

I then checked the performance vis a vis of the official nanovna-v2
specifications <https://nanorfe.com/nanovna-v2.html#specifications> .
Fortunately, on the positive side, there was no problem regarding the
S21
dynamic range and regarding the S11 noise floor that both met the nanovna
V2 specifications. However I was a bit puzzled to discover that the
return
loss of port 2 of my clone was unfortunately much higher than what is
officially specified....

official return loss specifications for port 2
20dB at 1.5 Ghz, 13 dB at 3 ghz

my measurements after calibration (see picture)
15.7 dB at 1.5 Ghz and 9.5 dB at 3Ghz

I wondering if
- I am doing something wrong the way I did this measurement
- if I am the only owner of a clone with this specific performance
problem
on port 2
- if owners of the genuine nanovna V2 also have the performance issue
- what is the value of the attenuator that you possibly use on port 2
during calibration to compensate for the sub-optimal return loss (I use
between 6 and 12dB depending on the accuracy I need and the dynamic
range I
am willing to sacrifice)

Thanks for sharing your return on experience regarding this issue

[image: image.png]






Peter Ide-Kostic <on7yi.pik973@...>
 

Any one with bad return loss on port 2 (less than 20dB) at 1.5 Ghz ?

On Sun, Aug 16, 2020 at 11:18 PM Peter Ide-Kostic via groups.io
<on7yi.pik973=gmail.com@groups.io> wrote:

Thank you for your reply

1) Please find below the trace between 1.4 and 1.6 ghz, of course there no
change (as expected)

[image: image.png]
2) The cables are fine I am sure, they are quality SS405 cables of 25 cm

3) To make a long story short, it is the owner of the Aliexpress shop
himself who informed me that he could no longer deliver the genuine model
<https://nanorfe.com/nanovna-v2.html#> that I had initially ordered in the
April time frame as he had switched supplier. I do not want to enter into
details but I was quite lucky with this specific transaction on aliexpress,
I waited a very long time (with at least 3 different shipping attempts) .
When the device finalmly arrived it had been damaged by transport . The
seller then simply offered me to send me the models coming from his new
supplier which I have accepted.

On Sun, Aug 16, 2020 at 10:55 PM CT2FZI <ct2fzi@...> wrote:

Did you calibrate from 1.4GHz to 1.6GHz and tried to measure it again?

Did you tried using another cable?

Why you say it's a clone?

Cheers

A domingo, 16/08/2020, 21:48, Peter Ide-Kostic <on7yi.pik973@...>
escreveu:

Hello,

I bought a nanovna V2 <https://nanorfe.com/nanovna-v2.html> on
Aliexpress
a
while ago. When I received it, I realized that it was a clone which I
did
not expect, but ok, I managed (as usual)

I then checked the performance vis a vis of the official nanovna-v2
specifications <https://nanorfe.com/nanovna-v2.html#specifications> .
Fortunately, on the positive side, there was no problem regarding the
S21
dynamic range and regarding the S11 noise floor that both met the
nanovna
V2 specifications. However I was a bit puzzled to discover that the
return
loss of port 2 of my clone was unfortunately much higher than what is
officially specified....

official return loss specifications for port 2
20dB at 1.5 Ghz, 13 dB at 3 ghz

my measurements after calibration (see picture)
15.7 dB at 1.5 Ghz and 9.5 dB at 3Ghz

I wondering if
- I am doing something wrong the way I did this measurement
- if I am the only owner of a clone with this specific performance
problem
on port 2
- if owners of the genuine nanovna V2 also have the performance issue
- what is the value of the attenuator that you possibly use on port 2
during calibration to compensate for the sub-optimal return loss (I use
between 6 and 12dB depending on the accuracy I need and the dynamic
range I
am willing to sacrifice)

Thanks for sharing your return on experience regarding this issue

[image: image.png]








@switchabl
 

Peter,

I have attached a measurement of port 2 return loss from my NanoVNA V2, bought from tindie. This one seems to be meet the specs (-20.3dB @1.5GHz and -15.5dB @3GHz).

There is also significant ripple on your measurement. It looks like your calibration is bad and you have significant residual source match error (or possibly your cable is bad, but less likely; since you are calibrating directly at the port 1 connector, you are measuring the cable as well). So I would take the results with a grain of salt. Mine is not perfect either, but it looks a lot less bad.


Peter Ide-Kostic <on7yi.pik973@...>
 

Hello,

Thank you for your anwer

Ok, please find below the same test but done without any cables on port 1
and only a through cable to connect to port 1 and port 2. I have also used
400 points to get a clean accurate trace with as little noise as reasonably
possible.


=> At 1.5 Ghz; the return loss on port 2 is still significantly too low
(15.5 dB vs 20dB) expected, *so no changes*

=> At 3 Ghz, the return loss has improved significantly, *it is now 14.7 dB
which is a bit better than the 13dB specified officially.*

=> At 2.33 Ghz, the return loss is 11.7 dB is which is much too low, it
should be minimum 13dB according to the specifications


[image: image.png]


*Conclusion*: my measurements and yours simply confirm that the return loss
on port 2 of my nanovna 2 clone is unfortunately not as good as the one
of your genuine nanovna V2 model <https://nanorfe.com/nanovna-v2.html> .
This is the confirmation that I wanted to have (thanks for your help). I am
not saying all the nanovana V2 clones systematically under perform on port
2 the return loss, but on the other hand, if I have the issue then other
clown owners may have it too (quite common sense really). It will not
prevent me from sleeping at night, but at least I know....

Kindly note that the quality of the calibration loads and of the SS405
cables that I used for this test are perfectly OK.

Thanks
Regards
Peter

On Mon, Aug 17, 2020 at 8:47 PM <@switchabl> wrote:

Peter,

I have attached a measurement of port 2 return loss from my NanoVNA V2,
bought from tindie. This one seems to be meet the specs (-20.3dB @1.5GHz
and -15.5dB @3GHz).

There is also significant ripple on your measurement. It looks like your
calibration is bad and you have significant residual source match error (or
possibly your cable is bad, but less likely; since you are calibrating
directly at the port 1 connector, you are measuring the cable as well). So
I would take the results with a grain of salt. Mine is not perfect either,
but it looks a lot less bad.




aparent1/kb1gmx <kb1gmx@...>
 

Mine (early amazon buy at 39$, that has internal shielding) meets 20db+ to
its upper limit (900mhz). Since primary usage is less than 500mhz its adequate.

If I need better I just put a 6DB pad ahead of port 2, then there is no question.

Allison
-----------------
No direct email, it goes to bit bucket due address harvesting in groups.IO