开云体育

Update to last edy555 code:

added Q factor format trace (See FORMAT->MORE->Q FACTOR)

Now AntScope2 can detect NanoVNA (see my post /g/nanovna-users/message/14317), but this software must better parse info data for correct detect device.

A lot of work for SD card support, size optimisation and standartization (all code for H version except SD card, upload to my github)
Rewrite standart ChibiOS Real Time Clock lib, it allow save ~1k flash
Speedup write to SD card (on good cards up to 800kB/s sector write speed, total write speed ~350-450 kB/s)

For NanoVNA-H remove debug info + new RTC code, and now still have free 7.5kB flash, it a lot of size for another features (now possible add exFat support, but only ~1k flash will be free)

Small changes for time command

time [y|m|d|h|min|sec] 0-99

Warning! command not check correct value size, not need set fot second 60-99 value and so on
For year 2020 need run 'time y 20'

As before LSI version for not installed external 32.768kHz quartz, LSE if instaled
I hope write autodetect, but it need rewrite ChibiOS code for all versions CPU)

Now more easy compile versions
This is pre-release code if all work ok, i remove debug info from H4 version and upload all fixes to github

For made screenshot need tab on BW text at bottom
For save s1p or s2p file SD Card-> SAVE ...

Info how install SD card slot and quartz for H4 see screenshots
For H version, only old PCB versions have not soldered SD card slot, for new version install slot difficult task.
See /g/nanovna-users/message/223

Solution used in the shop was U.FL adaptors to SMA, then offset the
plane of meausrement buy the needed distance in picoseconds.

At below 30mhz its not an bit issue.

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

I think I was using Hugen's but I switched to Edy555's and it seems to be an improvement. Thanks!

On Fri, Jun 19, 2020 at 11:45 PM, <david.hostetler@...> wrote:

I purchased an RF Demo Kit (picture attached) that uses SMA to u.fl cables to
attach VNAs to a small circuit board with 18 different circuits on it.

Hello David,

There was already a longer thtead started December last year:
/g/nanovna-users/topic/rf_demo_kit_testing_tutorial/65778338

73, Rudi DL5FA

Any good VNA can be used to evaluate preamps. However, remember to
consider IP3 and the max input that may yield 1 dB compression at the
output. When driven too hard, the device will not perform as it would with
a weak signal, which is your goal. Also, and I won't belabor the point as
it has been previously mentioned, best NF is generally not best match.
Rely on the published noise S-Parameters.

While not an instrument to measure absolute noise figure (but it can be
calibrated), the gated noise source is good for setting gain, bandwidth,
and noise figure. Zener diodes make wonderful noise sources when biased
near or at the knee. You can 'gate' them using the square wave output from
any signal generator and view the output on a spectrum analyzer. The
'noise output' impedance can be stabilized by installing a 50-ohm loss pad
between the Zener and the noise output. 5 dB of attenuation will assure a
worst case match (or known source impedance) of 2:1 SWR, or a return loss
of 10 dB. Best noise figure will occur when the noise on vs. noise off is
at a maximum. Using a broadband noise source, you will also be able to
view the bandwidth and, to an extent, the gain whether for max, best match,
and/or best NF. Even without a spectrum analyzer, you can set the preamp
for best NF using an o'scope with adequate bandwidth. If you can find or
buy a calibrated noise source (which I gave $5.00 for at a local ham
swapmeet several years ago), you will have an absolute measurement of NF.
When I found it on the table, the guy selling it commented, "Who wants more
noise"?! Little did he know the multiple uses of a calibrated noise
source!!

Dave - W?LEV

--
*Dave - W?LEV*
*Just Let Darwin Work*

Here is the picture. LOL

I purchased an RF Demo Kit (picture attached) that uses SMA to u.fl cables to attach VNAs to a small circuit board with 18 different circuits on it. When I calibrated my H4 using one cable and using the Short, Open and Load on the PCB, I got the expected results on the 33 ohm, 75 ohm, 3 dB attenuator and 10 dB attenuator across 10 MHz to 1.5 GHz. The attenuators were open on the output side so the return loss was 6 and 20 dB. I didn't try any thru tests.

About $25 on Amazon, less from eBay and China.

Hope this info is helpful.

I'm not sure exactly what you want, but my NanoVNA H4 can find the minimum
value for SWR or s11, whichever is selected. Choose "Marker" > "Search" >
"Minimum" and then "Search Left" or "Search Right."

I did this with my 4 band (40-20-15-10 meters) vertical antenna. I chose
5.0 to 30.0 MHz as the range. I was impressed. The display matches what my
RigExpert AA-600 displays. The routine I listed above would go right to the
dips. I found that my antenna also has minor dips around 9 and 25 MHz.

73, Zack W9SZ


On Thu, Jun 18, 2020 at 8:37 PM John Dusek <johndusek3@...> wrote:

Following up on this thread 6 months later. Does anyone know if there has
been any firmware development performed on a function to track the lowest
SWR for the nanoVNA?

John - W3JED

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

Yeah, I know. I've designed a lot of preamps optimized for noise figure if
the s-parameter file also includes noise optimization files. Generally, the
input is not a conjugate match when the NF is optimized. This was just to
get me in the ballpark for now. Central States VHF and MUD conferences and
others generally have noise figure testing equipment on hand and the
operator will optimize your preamp for you if is doable. But they have all
been cancelled fro this year, so I'll have to wait till next year unless I
come upon someone with NF equipment (which I don't have myself). Some day
...

That's a good idea on putting the attenuator on the input instead of the
output. Looking at the documents, I see the output is in the range of 0 to
-7 dBm. And like I said, I haven't seen anything about using the NanoVNA
with an active device. Maybe it's lost in the long set of threads of this
reflector, but there were no documents in the "Files" section that I could
find that covered it.

73, Zack W9SZ

On Fri, Jun 19, 2020 at 12:15 AM <david.hostetler@...> wrote:

Optimizing the S11 of a pre amp usually doesn't result in best noise
figures and hence best overall receiver sensitivity. Also having too much
gain in a pre amp may cause overload and intermodulation.distortion in the
receive system. When my job was designing add on VHF pre amps, we aimed for
closer to 12 dB gain.

Also, CH0 has a relatively strong output and connecting directly to the
pre amp input could cause the output to be very high, possibly pushing it
to compression, causing false gain readings and making the bandwidth spread
wider than it really is.

I would put 20 - 30 dB between CH0 and the input and connect the output
directly to CH1.

But this discussion has made me wonder if there is a way to use a VNA for
noise figure optimization.

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

Hi David,

Thank you for your answer.

In between, i found the "problem".

The USB port was connected to a battery powered PC.

The NanoVNA's CH0 port was connected to a grounded frequency meter,
powered by the main.

After a main power fail, a fatal overvoltage arrived and the NanoVNA's
USB interface was killed.

Results, no more USB connection; no red line active and no battery
charging possible.

May be, a better USB protection would be required...but for the price...

Regards,

Rudi

PS I ordered a NanoVNA-H4 and i will take it totally disconnected when
not in use...
=====================================

Sorry to hear that. Still a pain, Rudi, but better to destroy a $80 (or whatever) device than a $8000 one!

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

Hi David,

Thank you for your answer.

In between, i found the "problem".

The USB port was connected to a battery powered PC.

The NanoVNA's CH0 port was connected to a grounded frequency meter,? powered by the main.

After a main power fail, a fatal overvoltage arrived and the NanoVNA's USB interface was killed.

Results, no more USB connection; no red line active and no battery charging possible.

May be, a better USB protection would be required...but for the price...

Regards,

Rudi

PS I ordered a NanoVNA-H4 and i will take it totally disconnected when not in use...

Have you tried a different USB cable?

Does anyone know of a reasonably priced U.Fl calibration kit?

Thanks,
Mark

Hello Rudi,

The performance of my device was initially very poor. It was one of the early "bad clones" without shields.
The S11 at 900 MHz was in the range of -30 dB, S21 -40 dB.
So i made some modifications.
I added two shields to the RF parts (0.5 mm brass sheet) and a 68 uF / 10 V tantalum capacitor from the 5 V trace to ground (near the TCXO).
I also added 3 100 nF caps to C40, C42 and C44.
Before soldering the shields to the PCB i modified the TX and RX bridges as mentioned above.
Last i soldered C38 - 4.7 uF and TF1 - the SD card holder (below the LIPO pack, unpopulated on my PCB).
I replaced the LIPO by a 2100 mAh (Samsung).
The screenshot You saw are the results of theese modifications when connecting two good SMA 50 Ohm terminators (Teleg?rtner) to the two ports.

Best regards
Bert

Link to the nanorfe store? According to the website it is not open yet:
"The NanoRFE store is planned to open in July 2020 and will have the NanoVNA V2 in stock."


================================================

... and no mention of a big-screen, cased version either.

Guess I'll have longer to wait....

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

On Fri, Jun 19, 2020 at 01:07:49AM +0800, Gabriel Tenma White wrote:

Most clones of the V2 now perform ok, but consider buying from the Tindie store/nanorfe if you want to support the original developers (only these two stores remit a percentage of profit to the developers).

Link to the nanorfe store? According to the website it is not open yet:
"The NanoRFE store is planned to open in July 2020 and will have the NanoVNA V2 in stock."

On Fri, Jun 19, 2020 at 10:56 AM, <bert_winkler@...> wrote:

The firmware i use is version 0.9.3.3 beta FAT16/FAT32 SD card by DiSlord.
This combination of hardware and firmware gives good results up to 1.5 GHz.
The S11 up to 1.5 GHz is better than 50 dB.
The S21 up to 1.5 GHz is better than 60 dB.

Hello Bert,
I am using the same firmware version 0.9.3.3.
Congratulation about the good hardware you have.
Mine is not so good.

If you want to show your screenshot in the forum, it is better to convert .BMP to either .jpg or .png format.
See attached screenshot Bert_50D35603.png
73, Rudi DL5FA

Hello Rudi,

Sorry, in my NanoVNA R24 - 91 Ohm.

Bert

Hello Rudi,

In hugen79 H4 schematic there ara two versions of the RX input bridge.
From version 4.2
R24 - 91 Ohm
R22, R23 - 51 Ohm
R25 - 11 Ohm
From version 4.2.1
R24 - 56 Ohm
R22, R23 - 240 Ohm
R25 - 49.9 Ohm
In my NanoVNA i use
R24 - 56 Ohm
R22, R23 - 49.9 Ohm
R25 - 11 Ohm
I also tested R22, R23 - 51 Ohm - does not make big difference.
The firmware i use is version 0.9.3.3 beta FAT16/FAT32 SD card by DiSlord. This combination of hardware and firmware gives good results up to 1.5 GHz.
The S11 up to 1.5 GHz is better than 50 dB.
The S21 up to 1.5 GHz is better than 60 dB.

Best regards
Bert

On Fri, 19 Jun 2020 10:00:27 +0200, you wrote:

Hello,

Since this morning, my NanoVNA-H don't accept the USB connection.

I tried on 3 different PCs, no success.

On battery, all is ok but i'm not able to do charging.

I suspect an USB interface failure but i'm not sure...

What can i do ?

Thank you for your help.

Rudi

Why don't you look into the Device Manager.


W.