开云体育

I have measured the Cal-Kit supplied with my nanoVNA from AliExpress Guangyi0016 Store.

- The load has better than 40dB RL below 300MHz. It reaches 30dB at 840MHz.
- The short has zero delay, it looks like an ideal zero from DC to 900MHz.
- The open has 22fF capacitance (C0). I found C1-C3 coefficients not needed to model the open at these frequencies. Even up to 6GHz, the error is lower than 1deg.

Measurement done with an Anritsu MS4623B VNA properly calibrated with a 3750R CalKit after 2h warmup and using 10x averaging.

Carlos

a BNC kit bought from SDR kits where all these data are supplied with the kit

I just received mine and discovered they also offer a 4-piece kit,
where the added female-female barrel adapter supports female calibration:

On Sun, 6 Oct 2019 at 19:26, Oristo <ormpoa@...> wrote:

If the NanoVNA could provide a negative Electrical delay it could be
fixed.

IMHO, we really need a way of *properly* defining a calibration kit in
*firmware*. That means as a minimum a delay, (which can be negative), and
at least fixed capacitance C0 to support *professional* cal kits.

To support poorer kits C0, C1, C2, C3, L0, L1, L2, loss terms and
impedance.

Dave.


--
Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...

Telephone 01621-680100./ +44 1621 680100

Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United
Kingdom

If the NanoVNA could provide a negative Electrical delay it could be fixed.

There is at least room in the firmware menu to add a "negative delay" menu item, under e.g. "CONFIG"..

Hi Oristo

Yes if you load is also perfect 50ohm but such a load cost many $ ? although the load supplied with the NanoVNA is pretty fine and you correctly mentioned "observe no appreciable reflection" which requires both the candidate cable and load are good quality. Have a look at AC6LA home page about ZPlots and the his coac calbe information where you see the velocity factor which has influence on the delay is frequency dependent. He has a direct graph on this issue
Good luck with your experiment

Kind regards

Kurt



-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af Oristo
Sendt: 4. oktober 2019 22:59
Til: [email protected]
Emne: Re: [nanovna-users] Cal-Kit Standards' Definitions



Thanks for the response!

Remember the Electrical delay assumes and ideal 50 transmission line

So, if I

* properly calibrate at the VNA port

* plug in a candidate cable terminated with calibration load

* observe no appreciable reflection



.. then that cable unterminated should be satisfactory for delay testing..

Thanks for the response!

Remember the Electrical delay assumes and ideal 50 transmission line

So, if I
* properly calibrate at the VNA port
* plug in a candidate cable terminated with calibration load
* observe no appreciable reflection

.. then that cable unterminated should be satisfactory for delay testing..

Hello Oristo
Yes just by using the Electrical delay, but there is always a but, the delay in a transmission line is frequency dependent and if the impedance is not precise 50 ohm we might have an impact too. You may also use a phase trace and observe at what frequencies the delay is constant for which the it goes horizontal along thee 0 degree phase line. Changing the delay setting you may find at which specific frequency it crosses 0 degree thus determining the delay at that frequency. Remember the Electrical delay assumes and ideal 50 transmission line so....
Kind regards
Kurt

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af Oristo
Sendt: 4. oktober 2019 15:30
Til: [email protected]
Emne: Re: [nanovna-users] Cal-Kit Standards' Definitions

every user would need to compute a value for the delay, which would be
different for the value in the cal kit.

If I correctly interpret Kurt, then with appropriate software:
* attach an unterminated length of balanced transmission line
* interactively dial that delay so that Smith plot does not spiral inward

every user would need to compute a value for the delay,
which would be different for the value in the cal kit.

If I correctly interpret Kurt, then with appropriate software:
* attach an unterminated length of balanced transmission line
* interactively dial that delay so that Smith plot does not spiral inward

On Sun, 29 Sep 2019 at 17:40, Jeff Anderson <jca1955@...> wrote:

On Sun, Sep 29, 2019 at 03:43 AM, Dr. David Kirkby from Kirkby Microwave
Ltd wrote:

The 85032F is not one of Keysight’s best kits.

Hi Dave,

You are probably right. I chose this kit because, of the 50-ohm cal-kits
listed by Keysight as supported for the 8753D, it seemed to have the worst
higher-order capacitance terms, thus a good choice for testing my theory.

Although more difficult to implement in the firmware, and a PITA for users,
it would not be surprising if even better performance could be obtained by

* Setting C0 to 0
* Reading C1 from the datasheet of the cal kit
* Adjusting the offset delay from the data in the cal kit, to some longer
delay, which would depend on C0. That way only two parameters are entered
into the cal kit definitions (a delay and C0). The problem would be every
user would need to compute a value for the delay, which would be different
for the value in the cal kit.

But as an academic exercise - you have convinced me that for the
professional calibration kits, used up to 1500 MHz, an offset delay and C0
are fine.

Best regards,

- Jeff, k6jca

Dave, G8WRB

Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100

Hi Jeff

All my (I think more than 100) are in the folder ..../VNWA/ not accessible as such

I have an old promise to create a list but I am continuously on a new job about calibration so it will come some time when

And by the way my homepage suffers serious of age too

the steam pressure has lowered ?

Kind regards

Kurt

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af Jeff Anderson
Sendt: 30. september 2019 15:15
Til: [email protected]
Emne: Re: [nanovna-users] Cal-Kit Standards' Definitions



On Mon, Sep 30, 2019 at 05:57 AM, Kurt Poulsen wrote:

Here is another handy document of general interest

<> basic knowledge about a transmission

line.pdf I still have a problem to create it as html Hm....

Hi Kurt,



Here's the link (I hope!): <>



By the way, if I go to your top page, <> , I don't see this PDF listed in the contents. Did I miss it?



- Jeff, k6jca

Hi Erik

My Outlook 2019 sucks ?

Kind regards

Kurt



-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af erik@...
Sendt: 30. september 2019 15:14
Til: [email protected]
Emne: Re: [nanovna-users] Cal-Kit Standards' Definitions



On Mon, Sep 30, 2019 at 05:57 AM, Kurt Poulsen wrote:

<> basic knowledge about a transmission line.pdf

<>



Interesting example on how to get rid of the remaining osculation due to fringe C/L of the calibration load

Here is another handy document of general interest

Added to Wiki: /g/nanovna-users/wiki/Application-Notes

On Mon, Sep 30, 2019 at 05:57 AM, Kurt Poulsen wrote:

Here is another handy document of general interest
basic knowledge about a transmission line.pdf
I still have a problem to create it as html Hm....

Hi Kurt,

Here's the link (I hope!):

By the way, if I go to your top page, , I don't see this PDF listed in the contents. Did I miss it?

- Jeff, k6jca

On Mon, Sep 30, 2019 at 05:57 AM, Kurt Poulsen wrote:

basic knowledge about a transmission line.pdf

Interesting example on how to get rid of the remaining osculation due to fringe C/L of the calibration load

On Mon, 30 Sep 2019 at 13:46, Kurt Poulsen <kurt@...> wrote:

Hi Oristo
Thank you for your lingual suggestions
I have printed your input for picking up any more suggestions.
Kind regards
Kurt

Kurt,
it might be worth creating a fake Touchstone file with an exponentially
decaying amplitude, “modulated” with a sine wave - I *think* that would
produce the right result. If you exaggerated the problem with a bit of fake
data, it would be easier to see.

Dave
--
Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...

Telephone 01621-680100./ +44 1621 680100

Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United
Kingdom

Hi Erik
Thank you for the link in html I tried to change my response to html but is failed
Here is another handy document of general interest
basic knowledge about a transmission line.pdf
I still have a problem to create it as html Hm....
Kind regards
Kurt

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af erik@...
Sendt: 30. september 2019 07:34
Til: [email protected]
Emne: Re: [nanovna-users] Cal-Kit Standards' Definitions

Kurt.

Thanks for these documents, I updated the link as this will work




It helped me to understand some calibration problems w.r.t. reference planes

Erik.

Hi Oristo
Thank you for your lingual suggestions
I have printed your input for picking up any more suggestions.
Kind regards
Kurt

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af Oristo
Sendt: 30. september 2019 11:32
Til: [email protected]
Emne: Re: [nanovna-users] Cal-Kit Standards' Definitions

C%20calibration%20kit.pdf

I am still puzzling thru this. On page 3:
"As seen the trace is not flowing the circumference off the Smithchart which must spiral inwards in a progressive way."

.. evidently "flowing" should be "following" and "off the Smithchart"
should be "of the Smith chart".
I >>guess<<: " which must spiral inwards in a progressive way" should be understood "but is spiraling inwards", e.g.

"Instead of following the Smith chart circumference, the trace is seen spiraling inward."

.. where this trace is from an unterminated non-ideal cable (not airline), and changing (50 Ohm) LOAD shunt capacitance value C from 51.8 to
-108.2 improves "calibration".

I am still puzzling thru this. On page 3:
"As seen the trace is not flowing the circumference off the Smithchart
which must spiral inwards in a progressive way."

.. evidently "flowing" should be "following" and "off the Smithchart"
should be "of the Smith chart".
I >>guess<<: " which must spiral inwards in a progressive way" should
be understood "but is spiraling inwards", e.g.

"Instead of following the Smith chart circumference, the trace is seen
spiraling inward."

.. where this trace is from an unterminated non-ideal cable (not airline),
and changing (50 Ohm) LOAD shunt capacitance value C from 51.8 to
-108.2 improves "calibration".

Kurt.

Thanks for these documents, I updated the link as this will work




It helped me to understand some calibration problems w.r.t. reference planes

Erik.

Mr. Poulsen, very nice pages and work. Great primer explaining reference planes and delays. I think I'm going to have to read it a few times to absorb everything. I hope someone will modify the calibration instructions in the group files section to include your suggestion and reasoning for not using the open load during calibration.

Jim KA6TPR