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Re: RF Demo Kit Testing tutorial released

 

Test field 8 is a series LC. Hence at DC this is an Open.

It most have a trajectory that rotates CW and cross the short side of the chart at the series resonate point. There after the Z must be dominated by the L value and the rotation is confined to the upper portion of the chart.

It is a shame from an instructional point of view that the explanations for each of these test beds is so terse.


Re: Amplitude calibration

 

Just to be clear, you are saying that the vna gives an insertion loss that is different than what the SA TG provides and the difference is as much as 2- 3 dB?


Re: Amplitude calibration

ejfelix4976
 

There is a 2 to 3 dB difference between what the spec an says and the nanoVNA.
I know the spec an is good as it is calibrated.


Re: Amplitude calibration

 

Is there a difference in S21 after thru calibration using a direct cable between CH0 and CH1?
That should not be as the thru calibration should normalize S21

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK


Re: RF Demo Kit Testing tutorial released

 

On Fri, Jan 10, 2020 at 07:15 PM, Klaus W?rner wrote:

Your Smith chart 8.png of test field 8 (470 nH) shows at low frequency an
Open.
That can not be correct.
This is correct. 8 contains a series capacitor. This is an isolator at low
frequency.
Hello Klaus,
It looks like, tha we have slightly differen PCB layouts.
My PCB layout was posted in number 9245.

73, Rudi DL5FA


Re: RF Demo Kit Testing tutorial released

 

On Fri, Jan 10, 2020 at 07:07 PM, Klaus W?rner wrote:

Yes. The other ones are OK.
Hello Klaus,

I am glad that your RF Demo Kit now works as it should.
I think it is mainly for learning, and not for every day work.

73, Rudi DL5FA


Re: Amplitude calibration

ejfelix4976
 

Thanks for the replies!
Actually My spec an has a tracking gen which I normalize.
I noticed after doing a cal on the nanovna and nanoVNA F that there is a 2 to 3 dB difference in the measurement.
Used the same cables and the frequency was 6.5M to 14.5M on both
RBW was 3 KHz
I know the spec an is good.
I was curious if there is a way to adjust the Nanovna calibration to reflect the same value.


Re: nanovna that continues to indicate 50 ohms when S11 is open

Bob Albert
 

Sometimes the 'scale' function needs to be reset to 1:1.
Bob

On Friday, January 10, 2020, 10:08:45 AM PST, Torbj?rn Toreson <torbjorn.toreson@...> wrote:

Quite right, whatever impedance but no signal in on CH1 will show 50 ohm. Thanks.
/Torbjorn


Re: Poor Manual

 

From: Robert E. Gross

Where can I get better manual or instructions?
==========================



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


Re: RF Demo Kit Testing tutorial released

 

Your Smith chart 8.png of test field 8 (470 nH) shows at low frequency an
Open.
That can not be correct.
This is correct. 8 contains a series capacitor. This is an isolator at low frequency.


Re: nanovna that continues to indicate 50 ohms when S11 is open

 

Quite right, whatever impedance but no signal in on CH1 will show 50 ohm. Thanks.
/Torbjorn


Re: RF Demo Kit Testing tutorial released

 

Yes. The other ones are OK.


Re: We started selling nanoVNA-H4 using STM32F303CCT6 and 4-inch LCD

 

Hugen - Nice work. I am looking forward to working with the improved version.

On the alibaba page, the four inch model is the more expensive of the two listed, correct?

Cheers, bill


Re: nanovna that continues to indicate 50 ohms when S11 is open

 

50 ohm on CH1 means no input signal to CH1 as expected

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK


Re: nanovna that continues to indicate 50 ohms when S11 is open

 

Colin,

What You see in blue on the screen is the CH1 Smith Chart and the value off 50 ohm is to best of my knowledge the input impedance of CH1. Switch to Channel 0 reflect and the marker will jump to the right sida showing infinity. I just tested that myself since I was curious of the 50 ohm on an open CH1. Calibration with SOL on CH0 will not affect what You see on CH1.
Regards/Torbjorn


Re: nanovna that continues to indicate 50 ohms when S11 is open

 

Hi Hugen,

True, it was sold as an original with the latest software. I soon realized that this was unfortunately not entirely true :-(
This was before I discovered this forum and read that there were a lot of clones¡­

Thank you all for your response. I will, as Hugen advises, first try to update the software.


Re: We started selling nanoVNA-H4 using STM32F303CCT6 and 4-inch LCD

 

From

Quote.....

"NanoVNA is a very compact and portable vector network analyzer created by Mr. TAKAHASHI Tomohiro(edy555), which cost is very low. It is easy to manufacture and provide good measurement accuracy. Mr. Takahashi uses the GPL protocol to open source the NanoVNA software, aiming to attract more young people to pay attention to radio frequency and wireless. Based on Mr. Takahashi's software, I made simple modification to make it measure with odd harmonic. What's more, I have made a version that can measure 900MHz and shared it in the community, which has received widespread attention from the community. Later on, I started to mass produce NanoVNA. At the suggestion of Mr. Takahashi, I renamed my version NanoVNA-H. The community began to contribute new code for NanoVNA, new features were added, cho45 added TDR and screenshot functions to NanoVNA, and QRP73 helped to improve the driver of Si5351 and AIC3204. With more functional requirements being raised, the resources of STM32F072CBT6 are not enough, therefore, under a discussion with Mr. Liao(AA6KL) at /, he proposed the idea to replace STM32F303CCT6 with STM32F072CBT6. I provided Mr. Liao a NanoVNA-H test version with STM32F303CCT6. Thanks to Mr. Takahashi's early work, the porting was smooth. Because the STM32F303CCT6 has a faster SPI bus speed, we started to consider the display size problem which is widely complained by the community. After some selection and testing, we finally used a 4-inch LCD screen.

After discussion with Issues # # 14, we have now increased the measurement frequency of NanoVNA to 1.5GHz. With the larger screen, we have more PCB space for components and batteries. Therefore, we use a separate charge pump to power the mixer and add tantalum capacitors, which can further reduce power supply noise, and the 1950mAh battery can be used independently for more than 8 hours. We add DC dimming to the 4.0 inch full-view LCD screen, which make the view more clearly when used outdoors and more comfortable when used indoors.

In order to make it easier for geeks to create more possibilities, UART1, PC14, and PC15 are introduced on the PCB. Thanks to the manufacturing experience of NanoVNA-H, we made a new ABS shell for NanoVNA-H 4, which can effectively protect SMA connectors and switchs. Each set of NanoVNA-H 4 sold to the community is installed with a complete ABS shell. It is packed in a beautiful gift box, which can surely protect the NanoVNA-H 4 without being damaged during the long-distance express transportation. NanoVNA-H 4 maintains high degree of software compatibility with previous versions of NanoVNA. All software developed for NanoVNA can be used directly. Just note that with the larger LCD screen, the data returned by the ¡°capture¡± command is twice as long as the original one, but the developers can easily modify the code for compatibility.

I'm selling the full NanoVNA at gen111.taobao.com, if you are an overseas user, you can purchase the hardware I made through alibaba. If you need to trade with PayPal, please contact Maggie through Alibaba. you can also design your own PCB by reference schematic, it should be noted that analog circuit partial shielding and isolation are important, the bridge part is strictly matched, if you need to use harmonic extension 300M or more measurements need to pay special attention."


Re: nanovna that continues to indicate 50 ohms when S11 is open

 

I have also seen this. Bad calibration kit.
In my case the 50 ohm load did not connect well to the nut ring, which caused bad calibration.
Order a new one in good quality.

Best
Soren


Re: Amplitude calibration

 

You can measure a filter without a tracking generator and do want you desire... of course WHY. In any case, sure.

Set your generator to the same level as your vna. Stop the vna sweep so you can do this. Then run the generator direct to the SA. That is your zero reference and then insert filter under test. The measure is now IL and same as magS21.


Re: Amplitude calibration

 

On Fri, Jan 10, 2020 at 08:54 AM, ejfelix4976 wrote:

Just curious, is there a way to calibrate the output amplitude so that when measuring say a filter I can get it to read the same as a calibrated spectrum analyzer??
===============================================

Ed,
When measuring a filter with a spectrum analyzer the usual procedure is to do so in concert with a tracking generator. The S21 (thru measurement) on the NanoVNA accomplishes the same thing within the limits of its dynamic range.

- Herb