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Re: Supply noise at higher harmonics #internals

 

Using the console command "sample" it is possible to measure the pure reference, refl and thru signal strength.
First picture shows the change over frequency of the reference signals (only look at the changes in level, the absolute levels differ due to some TAPR VNA internals)
According to the internal gain setting table in the nanoVNA there is additional gain added as the frequency moves up. These are the vertical jumps, each about 5dB at 300, 600,900, 1200, 1500 and 1800MHz. In total about 45dB gain is added in the audio path to compensate for signal loss and with the 10dB delta between lowest and highest frequencies the delta is 55dB, similar to the 55dB measured with the direct connection to the SA612 so the nanoVNA adc and dsp algorithm do maintain the dynamic range.
Next picture shows what happens when you use a clean 5V supply. Much less noise in the reference signal.
The weird thing with the reference signal is the increase in strength above 1.5GHz. This could be caused by capacitive coupling in the attenuator before the reference mixer
Third picture is the change of the amplitude signal (red line) of reflection mixer without anything connected to the SMA CH0 connector, a fairly good open. The change of amplitude over frequency does not show any weird things. The green line shows the leakage from the output signal into the forward mixer. The pattern suggest the attached cable acted like an antenna
The fourth picture is the change of the amplitude of the forward mixer. (green line) with a through from CH0 to CH1.
The bridge (red line) stops working above 1.5GHz as the characteristic pattern of the cable disappears, possibly because of insufficient measurement SNR
Till now I have not been able to get valid phase signal from the bridge above 1.5GHz, only amplitude with at least 20% noise.
Comparing the absolute levels of the signals suggests there is about 10dB headroom for increasing the thru signal and about 20dB for increasing the reflection signal. In particular the latter might have a big impact in the performance of the bridge at higher frequencies.
I hope this information is not too detailed but writing it down helps me to understand it much better.


Re: errors of "error" models

 

#53 : Upgrade : The [LeastVNA]
-
after:
#48 : ann : update 3 of [LeastVNA] is withdrawn
15 October 2019
/g/nanovna-users/message/4945
-

Hello,

Allow us, please, to inform you that we just finished our research
regarding the [LeastVNA] description of [AnyVNA], which from
now on exists in our small objective world as the one given by
this 39 characters long expression:



Thank you very much indeed all of you who constructively
commented on this crucial matter !

Sincerely,

gin&pez@arg

53#


Re: Owen Duffy on improvised test fixtures #test-jig

 

I have made a test jig for my VNA based on a ZIF socket
test jigs added to Wiki Application Notes
/g/nanovna-users/wiki/Application-Notes


Re: Owen Duffy on improvised test fixtures #test-jig

 

I have made a test jig for my VNA based on a ZIF socket. I always measure
with the ZIF socket closed, even if nothing is locked into it. A short is
literally a tiny piece of wire a couple of mm long. The open is no wire,
and the load is a 1/8 watt 50 ohm resistor. The ground is soldered to one
row of the ZIF socket, port 1 is half the pins on the other row, and port 2
is the other half, so that the two ports only need to be bridged by about
2.5 mm to obtain the short measurement.

On Thu, Oct 17, 2019 at 11:15 AM W5DXP <w5dxp@...> wrote:

Martin
5:37am #5091

Martin - G8JNJ wrote: Owen is one I'd always listen to, even if
personally challenged by what he has said or written. It's happened to me,
I've learnt a lot in the process, and continue to respect him.

Ditto for me. After I decided to ignore the irrelevant emotional content,
I learned a lot from Owen Duffy.




Supply noise at higher harmonics #internals

 

When using the nanoVNA at frequencies above 300MHz it switches to harmonics mode
First attached picture shows the harmonics till 1600MHz of the SI5351 output when set at 100MHz.
The 9th harmonic is at 900MHz only 34dB below the fundamental at 100MHz.
To validate the performance of the SA612 I soldered two wires to output of the REF mixer and observed the output using a balanced USB audio input
Second picture shows the 8k audio FFT when the nanoVNA is set to 1MHz. About 100dB SNR at this small audio BW.
The nanoVNA uses less points (48) in its calculations and has therefore substantial less SNR
The third picture shows the output when set to 2GHz. The SNR is reduced to something between 20 and 30dB
This 80dB signal reduction is much larger as the reduction of power in the harmonics but can probably be attributed to the mixing loss in the SA612 as it it operated way out of spec (max 500MHz)
The fourth picture shows the roughly 50dB SNR you get when you operate the nanoVNA at 2GHz from a clean 5V supply. A very welcome improvement making S21 measurements possible.
A quick calculation based on the schematic suggests the REF mixer has the highest signal levels while the TRAN mixer is 10dB lower and REFL is 20dB lower
If I have enough courage I may change the attenuators for the REFL and TRAN mixer to get more balanced power levels.


Re: NanoVNA WebApp USB question

 

On Thu, Oct 17, 2019 at 11:45 AM, QRP RX wrote:


can anyone show the circuit and photo where this 5.1k resistor should be
installed. Is it possible to install it on NanoVNA-H pcb?
Have a look here:

You need to attach 5.1K resistors to ground from cc1 and cc2.

Scroll up the webpage to see the pins


Re: NanoVNA WebApp USB question

 

can anyone show the circuit and photo where this 5.1k resistor should be installed. Is it possible to install it on NanoVNA-H pcb?


Re: Owen Duffy on improvised test fixtures #test-jig

W5DXP
 

Martin
5:37am #5091

Martin - G8JNJ wrote: Owen is one I'd always listen to, even if personally challenged by what he has said or written. It's happened to me, I've learnt a lot in the process, and continue to respect him.
Ditto for me. After I decided to ignore the irrelevant emotional content, I learned a lot from Owen Duffy.


Re: NanoVNA WebApp USB question

 

Some people said that you can solder anything you see, so get a magnifying glass.
"Some people" have never experienced familial palsy.
"Some people" have good depth perception


Re: NanoVNA WebApp USB question

W5DXP
 

From: sala nimi: Some people said that you can solder anything you see, so get a magnifying glass.
"Some people" have never experienced familial palsy.


Re: Any ideas for test jigs?

Mel Farrer, K6KBE
 

I have been using a fixed L and a fixed C on 3.5 and 10 MHz. Works very
well in getting a quick check of calibration.

Mel, K6KBE

<>
Virus-free.
www.avg.com
<>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

On Thu, Oct 17, 2019 at 7:17 AM Oristo <ormpoa@...> wrote:

Perhaps a 500 ohms reactance would work in measuring.
Perhaps calibrating nanoVNA THRU using an RF Active Probe, e.g.





Re: errors of "error" models

 

#52 : Update : The compact SLO formula for [AnyVNA]
-
after
/g/nanovna-users/message/5081 - 17 October 2019
/g/nanovna-users/message/5075 - 17 October 2019
by Gary O'Neil
-
@Gary O'Neil:

Dear Gary,

Thank you very much for your most valuable comments !

Allow us, please, to ask you to give us enough time to prepare
our replies.

Meanwhile, take into account, please, that you already motivated us
to attempt to write a minimal set of statements, valid more-or-less
in ANY computer language having NO internal type of COMPLEX
variables and only a REAL one, regarding :

#42 : The compact SLO formula for [AnyVNA] - 12 October 2019
/g/nanovna-users/message/4747

in order to be ready for embedding them in ANY related program
by the interested reader of- and/or contributor to- this thread of
messages.

However, during the transferring of that formula to statements,
and after we found and corrected an existing typo in it, we
finally succeeded a further compactification of it, and thus
we updated it, as follows:



that is in a super-mini form most appropriate for this
particular work : Thank you - Please, stay tuned

Best regards,

gin&pez@arg

52#


Re: Any ideas for test jigs?

 

Perhaps a 500 ohms reactance would work in measuring.
Perhaps calibrating nanoVNA THRU using an RF Active Probe, e.g.


Re: NanoVNA WebApp USB question

 

Hugen,


If I order a NanoVNA-H today will it have the 5.1k Type-C CC resistors installed?


What is the link to your Nan0VNA-H site?


If someone does not have a NanoVNA with the resistors does this workaround when connecting to a USB Type-C port:


USB Type-C to USB Type-A Male cable (supplied with NanoVNA) to Type-A Female USB Type-C cable


Mike N2MS

On October 16, 2019 at 9:41 PM hugen@... mailto:hugen@... wrote:


The newly released NanoVNA-H has added the 5.1K Type-C CC resistors, which is already installed if it have a "NanoVNA-H V3.3" tag on your PCB.



Re: Owen Duffy on improvised test fixtures #test-jig

 

Hi

Perhaps the caption should have been "nanovna-saver ¨C a premature look".

I mean it is of version 0.1.0. I took a different approach than writing a blog entry, or webpage, about it, namely to engage in the evaluation, and report my findings and suggestions to Rune. So from a kind of "aaaahhhh, no thanks" to "OK, interesting - let's see what this can become."

Indeed I had my head scratching moments too. The very first one was the NanoVNA and -Saver and the indiscriminate use of CH#, Port# and S## (My NanoVNA measures S00, and S10 instead of S11 and S21 etc.). I did a lot of wrong calibrations. Yes, the return loss, S11 (S00), reflection coefficient are not three different names for the same thing. But I am sure we will get there.

With the very best of intentions
Bo


Re: Test fixtures #test-jig

 

Wow - you have a lot of time to look up all of these posts!Are you going to put all this in the application notes section of the wiki?

On Thursday, October 17, 2019, 9:40:12 a.m. GMT-4, Oristo <ormpoa@...> wrote:

> I have one of the $9.00 eBay bridges, and a noise source.
With a SDR as a detector I can do some Nano to Bridge comparisions, I hope.
Enhancing nanoVNA by an eBay 3GHz RF bridge is interesting.

Before getting nanoVNA, I considered using SDR and noise source with
eBay clone

Warren Allgyer seemingly reported comparable results
/g/nanovna-users/message/2484
using 3GHz bridge with nanoVNA vs nanoVNA alone,
which resistive bridge was analyzed by alan victor
/g/nanovna-users/message/1252

QRP RX described using nanoVNA to measure 3GHz bridge directivity
/g/nanovna-users/message/2880

Erik, PD0EK uses 3GHz bridge in his 35MHz - 3GHz breadboard VNA
/g/nanovna-users/message/2054
/g/nanovna-users/message/3422


Re: Test fixtures #test-jig

 

I have one of the $9.00 eBay bridges, and a noise source.
With a SDR as a detector I can do some Nano to Bridge comparisions, I hope.
Enhancing nanoVNA by an eBay 3GHz RF bridge is interesting.

Before getting nanoVNA, I considered using SDR and noise source with
eBay clone

Warren Allgyer seemingly reported comparable results
/g/nanovna-users/message/2484
using 3GHz bridge with nanoVNA vs nanoVNA alone,
which resistive bridge was analyzed by alan victor
/g/nanovna-users/message/1252

QRP RX described using nanoVNA to measure 3GHz bridge directivity
/g/nanovna-users/message/2880

Erik, PD0EK uses 3GHz bridge in his 35MHz - 3GHz breadboard VNA
/g/nanovna-users/message/2054
/g/nanovna-users/message/3422


Re: NanoVNA-Saver 0.1.3

 

Hi Rune , very happy for the new improvement on the 0.1.3 of nanovna-saver.
Suggestions for the future version :

1 Save the settings of nanovna , start stop center number segments , sweep mode , when saving the calibration ,not necessary as separate file , better in the same file. Recalling calibration file , the parameters will be update automatically.

2 Have a marker over the graphic for the main parameter , as a choice instead to display all data.

Many thanks again for your effort to improve the SW that is making the nanovna a very powerfull piece of hardware.

Best regards
Maurizio IZ1MDJ


Re: Abbreviated documentation for more simplistic tasks?

 

That said, there are number of useful tutorials on YouTube. Listing them
would also help new users.
Citing in messages helpful specific URLs applicable to nanoVNA (and
why) has value.


Re: NanoVNA-Saver 0.1.3

 

On Wed, Oct 16, 2019 at 09:22 PM, Martin wrote:


I've got some other info that may be of help, but I can't find the document at
the moment.
Hi Rune,

I still can't find my old paper notes on the subject of Cs, Cp, Ls and Lp but this Keysight document seems to be the closest to what I was looking for.

Section 1 of this document



Section A1-5 of the following is also useful and Table A1-3 in this document define the various formulae



Regards,

Martin - G8JNJ