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Hello,

I come back to you because I need information on the interpretation of the nanovna curves.
So I wanted to make a filter 4 poles from 2 filters 2 poles.
By simulating on a model the 45MHZ filter of the Ubitx I managed to have a relatively flat gain curve.
On the other hand, when I test with a generator, whether on the model or filter inserted in the Ubitx, I have a fluctuation of the signal.
To sum up I have a stronger signal at 44.992 or 45.005 than at 45.000Mhz.
I have the impression, in fact, that we follow the "loss" curve more than the gain curve during the measurement.
Therefore, I wonder if the measure is well done.???
What also surprises me is that in principle, the 2 filters 2 poles being connected together, the central leg (output 1 to input 2)must have a capacitor coupling to the ground.
If I put in a variable capacitor the gain curve is horrible regardless of the position, I actually put an impedance in parralelle sweat the capacitor and there only I have a correct gain curve, but the capacitor must be at 0.

so is it actually necessary with the best loss curve at the detrimant of the gain curve or other
cdt

I've had the same question for some time, but never bothered to ask. I've always just calibrated directly on the VNA because of what NanoSaver says.

Dave, can you please elaborate? Or anyone else? Why does the software have the waring/suggestion that it's calibrations be done directly on the NanoVNA?

yes, once you have calibrated in SAVER, you can store it on the laptop or
PC for future use.

Dave - W0LEV

--
Dave - W?LEV

Hello,

I've been using my Nano VNA as stand alone for a while and have recently started using the Nano VNA saver software for windows. I really like the software and find it very useful.

I've been using it with calibration made on the actual VNA itself, but have noticed that I can do it via the software also, which I thought might be worth doing. I didn't do it as I note the software suggests that it's actually better not to and rather calibrate via the VNA itself.

Does anyone have any input on this? I had hoped to create several calibration sweeps and save them via the software to make things easier to recall, plus being able to recall many scenarios.

Thanks,

Thanks Jim,

Yeah, I was wondering about calibration. I've seen some conflicting info online. Here's what I did.

Removed UUT.
For Isolation, I connected 50 ohm standards to both CH0 and CH1.
For Through, I connected CH0 directly to CH1.

Is that the right way?

73,

Phil

On 5/17/22 11:17 PM, Phil via groups.io wrote:

It's looking to me like my NanoVNA-H has an 87 ohm input impedance when I try to do a through measurement. Shouldn't it be 50?

Here's how I came to that conclusion:

I connected a 4.99k ohm resistor from CH0 to CH1,
Then I configured the NanoVNA as follows:
Display Format LOGMAG
Channel CH1 THROUGH
Then I did a calibration.
The display shows -35.2 dB.
The attenuation would be 10^(35.2/20) = 0.0173
Which means the NanoVNA's input impedance is 88.33(1-0.0173) = 87.5 ohms.

As a confirmation, I replaced the resistor with a 0.01 uF capacitor, and it was 3 dB down at 187 kHz, which is what I would expect for an input impedance of 87.5 ohms.

Am I doing something wrong here?

You should cal using the cal standards (i.e. a zero ohm thru), then make the measurement.

If you're doing the cal with the UUT in the loop, who knows what you'll get.


If you want to measure the Ch0 Z, you'd need to look at the actual cal coefficients (not the displayed values) calculated with a standard cal - I don't know that those are accessible. Or, reset the cal to none, measure some standards, and from that you can calculate the port's apparent impedance.


Or, hook up another NanoVNA, and directly measure it.

1/have you a copy of your soft ware 5.1.0
you need to look at bottom for plastic stuch under cove
this caught me out

It's looking to me like my NanoVNA-H has an 87 ohm input impedance when I try to do a through measurement. Shouldn't it be 50?

Here's how I came to that conclusion:

I connected a 4.99k ohm resistor from CH0 to CH1,
Then I configured the NanoVNA as follows:
Display Format LOGMAG
Channel CH1 THROUGH
Then I did a calibration.
The display shows -35.2 dB.
The attenuation would be 10^(35.2/20) = 0.0173
Which means the NanoVNA's input impedance is 88.33(1-0.0173) = 87.5 ohms.

As a confirmation, I replaced the resistor with a 0.01 uF capacitor, and it was 3 dB down at 187 kHz, which is what I would expect for an input impedance of 87.5 ohms.

Am I doing something wrong here?

73,
Phil

I had a similar issue with an H4. A firmware upgrade fixed it, and improved
the menu access, as well as the softkeys for setting frequencies.

Have you tried loosening the screws that hold the display in place?
There may be a short-circuit underneath.

Mike - M0MLM

------------------------------------------------------------------------
*From:* Rich NE1EE [mailto:TheDustyKey@...]
*Sent:* Tuesday, 17 May 2022, 1:54 pm
*Subject:* [nanovna-users] U.FL connector mating cycles

I recently found that I-PEX has some very explicit mating instructions.

I realize the method is provided for MHF I with LOCK, but I think it applies generally, and I have had great success with it.
I have been using the method described in the doc ever since my observations and experiments upon first running into these.
--
~R~
72/73 de Rich NE1EE
The Dusty Key
On the banks of the Piscataqua

On 16/05/2022 19:32, k6whp wrote:

..well, figured out how to flash the firmware with the app and, thanks to help here, I was able to do a cal first in order to make the new firmware retain the config I set up. My original goal is to brighten up the faint grid lines and am given to understand that this can be done via console commands in lieu of the missing "BRIGHTNESS" option on previous firmware.

I am using PuTTY to connect and having no success. It has been set up as a serial connection to COM10 (checked with my Windows 7 device manager) and the parameters are the same the as the app parms (shown in the attachments below). Each time I attempt to open the connection I get the missing file error message per the error message attached

Appreciate any help.

Perhaps something else is using COM10? The NanoVNA-Saver or whatever?

David
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

Roger,

Thank you for your assistance and advice. I was able to actually communicate with the NanoVNA and pass along commands. It is quite an incredible tool! My soncere gratitude for the talent and engineering that went into that!

I was even able to communicate with the NanoVNA using PuTTY and enter commands. As with the app, I was able to change the color of the grid lines ("color 2 0xFFFF", etc,) so i have the concept understood; just need to get the details.

..AND OF COURSE, like you tried to explain, the driver gets gets rolled out when the device is unplugged. Shoulda known!

All that said, PuTTY and the former "SAVE" app is really not needed as this "Swiss Arm Knife" does it all.

My thanks for your patience! This *is* gonna be fun!
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."

Attached is an annotated screenshot showing what some of the buttons do in NanoVNA app.

It should be enough to get new users started.

Roger

If you connect to a NanoVNA with a terminal program you need to set the baud rate to 115200 and no flow control.

Roger

On Mon, May 16, 2022 at 03:43 PM, k6whp wrote:

Roger,

Appreciate your assistance.

Well, it seems that my COM10 port./driver has disappeared and only COM1, COM2,
and LPT1 were left behind. I followed your link to the Box validation,
obtained an ID and proceeded to download the driver package. I attempted to
install the drivers per the two wizards and yet the Drivers remain the same.

PuTTY does not produce the previous error but instead displays a session that
does not respond. Wonder what I am doing wrong? I attached some screen
scrapes essentially tracking what I did.

If you have problems...
---------------
1. There are not two wizards for the drivers. There are four drivers in the zip file - two for Win 8 and two for WIn7. You have to pick one of the four and only run that install. For Win 7 pick the one that matches your system - 32 bits or 64 bits.

2. COM1 and COM2 are usually Windows defaults and you will see those with nothing plugged in. You won't see the one for the NanoVNA until you plug it in. You should hear a bing sound in Windows when you plug it in. After you plug in your NanoVNA and turn it on you should see an new Com port with the name STMicroelectonics Virtual COM Port. See attached screenshot.

3. After you install the driver plug it in and post a screenshot of Device Manager here....

4. There is no need to use Putty if you get NanoVNA app working. NanoVNA app has a built in Comms port so you can send console commands to the NanoVNA in a popup window. Attached is a screenshot showing which button to use and where to type commands. If you enter "help" it will return a list of commands. If you do nothing it will show you the traffic between the NanoVNA and the app (try running a sweep to see)

Roger

Roger

If you have problems...
---------------
1. There are not two wizards for the drivers. There are four drivers in the zip file - two for Win 8 and two for WIn7. You have to pick one of the four and only run that install. For Win 7 pick the one that matches your system - 32 bits or 64 bits.

2. COM1 and COM2 are usually Windows defaults and you will se those with nothing plugged in. You won't see the one for the NanoVNA until you plug it in. You should hear a bing sound in Windows when you plug it in. After you plug in your NanoVNA and turn it on you should see an new Com port with the name STMicroelectonics Virtual COM Port. See attached screenshot.

3. After you install the driver plug it in and post a screenshot of Device Manager here....

Roger

On Mon, May 16, 2022 at 03:43 PM, k6whp wrote:

Roger,

Appreciate your assistance.

Well, it seems that my COM10 port./driver has disappeared and only COM1, COM2,
and LPT1 were left behind. I followed your link to the Box validation,
obtained an ID and proceeded to download the driver package. I attempted to
install the drivers per the two wizards and yet the Drivers remain the same.

This topic is for NanoVNA app so please post Putty questions in your Putty thread so we don't hijack this topic.
I will reply to your Putty inquiries there...

Roger

On Mon, May 16, 2022 at 11:33 AM, k6whp wrote:

I am using PuTTY to connect and having no success. It has been set up as a
serial connection to COM10 (checked with my Windows 7 device manager) and the
parameters are the same the as the app parms (shown in the attachments below).
Each time I attempt to open the connection I get the missing file error
message per the error message attached

I believe you are using WIN 7. The problem could be that you do not have the correct driver installed for Windows 7. Windows 10 has the correct driver for the NanoVNA ready to go (or update will install it). With WIN 7/8/8.1 you have to manually install it.

After you do Device Manager will look like the attached screenshot. Note the description of the driver...

Here is a link to the WIN 7 and WIN 8 drivers for the NanoVNA on my Box drive. Download button in upper right hand corner. (Note: These are NOT the DFU drivers required for updating firmware)



Roger

Try 115,200 for the baud rate.

73

Stan
KM4HQE