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Learn about the NanoVNA in the following forum areas:

Documentation & Update Files:/g/nanovna-users/files

If you visit that link you will find:

1. //[email protected] </g/nanovna-users>
2. //Files </g/nanovna-users/files>
3. Absolute Beginner Guide to The NanoVNA

and then you will find:

Absolute_Beginner_Guide_NanoVNA_v1_6.pdf </g/nanovna-users/files/Absolute%20Beginner%20Guide%20to%20The%20NanoVNA/Absolute_Beginner_Guide_NanoVNA_v1_6.pdf>

-PE0CWK-



Op 20-10-2022 om 14:42 schreef Frank:

Hi All. I am a newbie here and I need a manual for my new NanoVNA-H4 and also step by step instructions on how to calibrate and save the cal data.

Frank

Nice results.

I did the same experiment with a Hugen 2.3 and had to move to S21 measurements for accurate results on 1-30 MHz.

Maybe, if I get around to it, I? will try these low/high resistance S11 measurements on an H4.2.

Thanks.

Arie PA3A

Op 20-10-2022 om 01:33 schreef jmr via groups.io:

It's also possible to post process the VNA data to do other things. Here's a chart of current gain vs frequency for the same 2N3904 at 10Vce and 10mA Ic. This chart is derived from the same dataset that produced the GMAX and K plots. You can see the VNA shows unity current gain at about 300MHz at 10Vce and 10mA Ic as this is the frequency where the current gain falls though unity on the chart.

If Ft is calculated at 20.19MHz (marker 4) the Ft is predicted to be 20.19 * 16.73MHz = 338MHz.

I often use a lab VNA to measure and model semiconductors up to many GHz. These 2 port models work well in practice and a lot can be learned about a transistor from these measurements.

In the plots below I measured a 2N3904 in common emitter at 10Vce and 10mA Ic. I also measured a MMBTH10 in common base at 10Vce and 3mA Ic. The plots show GMAX and K in each case. These models are taken using bias tees and a decent test fixture where the reference plane is set right at the pins of the SMD BJT.

The VNA predicts that (at 10Vce and 10mA Ic) the 2N3904 can produce about 15dB gain at 145MHz and about 8dB gain at 432MHz. It also predicts that the 2N3904 could go unstable and oscillate at just over 1GHz if configured as an oscillator as the K factor is still below 1 at 1GHz at this operating point. The MMBTH10 plot shows that the MMBTH10 BJT can oscillate at up to about 2.4GHz at 10Vce and 3mA Ic as K is still less than 1 here. This is the SMD version of the MPSH10 BJT.

You can't predict this behaviour from the datasheet. This shows how useful and powerful a VNA can be. I used an Agilent VNA for these plots rather than a nanovna.

On 10/19/22 3:26 PM, Leif M wrote:

"You can calibrate for any resistance"
Sure. But if those things can be made would it improve accuracy, when measuring low and high impedances.

Sure - and people do that - sometimes as part of a research project or dissertation.

Ultimately, what you do is look at what you need to measure, assess the uncertainty with your "50 ohm" equipment and go from there. Usually, it's a matter of SNR and accuracy of measurement of small changes. Looking at a 5 ohm circuit, the reflection coefficient is huge (0.8=45/55) and if you want 10% accuracy, you need to look at telling the difference between about 0.02 out of 0.8 (2%).

Z mag gamma
4.5 .834
5 .818
5.5 .801

The NanoVNA can easily make measurements to 2% or even 1%.

OTOH, if you need 1% accuracy, you're looking at needing a measurement to 0.2%.
The NanoVNA can still do that, but you'd better have really good cal standards, etc.

It's also going to be painful making accurate S21 measurements of lossy components, because you've got 15dB loss through the first reflection and the same at the output, so it's like having a 30dB pad in series with your UUT.



If you want to get really wild, look into "dembedding" - it's of vital importance in measuring circuits on a semiconductor die and they're rarely 50 ohms.

In addition, waveguide has a frequency dependent impedance that is also propagation mode dependent. And it calibrates out.

I've used near field antenna ranges which use a VNA as their core, with a open waveguide as the probe, and it's nothing even remotely close to 50 ohms. But it *can* be precisely calculated, and verified.

There's also VNAs that don't use the coherent transmitter/receiver like the NanoVNA. Look up 6-port analyzers - which use only power detectors (which can be made very accurate).

VNA errors get high when the mismatch is also high; we try to calibrate them out but it is an imperfect process. When we needed to measure the impedances of large L-band power bipolar transistors, with impedances in the single digits, we would use a low-impedance series microstrip line matching transformer to pre-match the impedance to something closer to 50Ω. We would use a break-apart fixture where we could measure the matching section separately and back its transformation out of the measurements. We'd measure two matching sections back to back to determine the losses. It was time-consuming and narrow-band.

For lower frequencies it might be worthwhile using a commercial (Mini-Circuits) 9:1 or 16:1 transformer backwards and do the same trick. Then the analyzer only needs to deal with measuring a 45Ω impedance (VSWR 1.11:1) rather than 500Ω (VSWR 10:1).

In the REAL Dark Ages We had an Alford 5Ω slotted line for measuring low impedances; SUPER tedious work. For high impedances, maybe an open-wire "Lecher line" could be used:
73, Don N2VGU

I have had success on my Baofeng using a female barrow between the Baofend RP and a rubber duck with a normal BNC.

Dave - WB6DHW

Across the 5MHz to 50MHz frequency range, it's still possible for a basic nanovna to make fairly accurate resistance measurements across a wide range of resistances using a basic s11 measurement. In the plot below I measured a suite of test resistors from 0.167? through to 330k? from 2MHz to 30MHz. You can see in the chart below that my little nanovnaH did quite well in these tests. It failed to measure the 330k? resistor but did OK across 0.167? through to about 100k?. At higher test frequencies the performance of the nanovna will degrade but I think the performance of the nanovnaH is quite impressive in the plot below. This was all done with a single s11 calibration.

I have had problems when I have accidentally used RP connectors. Two female connectors back to back do not work.

I can't edit my posts, so a second post. What I understand, NanoVna asn other VNAs are optimised for 50 ohms, they have for instance 50 ohms impedance bridge inside.

"You can calibrate for any resistance"
Sure. But if those things can be made would it improve accuracy, when measuring low and high impedances.

The test equipment standard in the RF/?wave industry is and has been for
some time 50-ohms. No, others are not made. The TV industry may have a
few dedicated instruments at 75 ohms, but that's about it. 50-Ohms is our
standard.

Dave - W?LEV

--
Dave - W?LEV

On 10/19/22 1:12 PM, Leif M wrote:

Do we need a VNA for 5 ohms and an other for 500ohms. Are they possible. Lets forget about 5 or 500 ohms attenuators, coaxials and such. But would it help if VNA is made for other impedances.

You can calibrate for any resistance

Do we need a VNA for 5 ohms and an other for 500ohms. Are they possible. Lets forget about 5 or 500 ohms attenuators, coaxials and such. But would it help if VNA is made for other impedances.

Has anyone produced a structure map for V1.2.14 firmware? If so, where is it located?
Thanks,
- John

The wiki page Home ( /g/nanovna-users/wiki/12336/174009 ) has been updated by Ho-Ro <homuth-rosemann@...>.

*Reason:* Mirror/clone of DiSlord's source repo with binaries of his recent commit

Compare Revisions ( /g/nanovna-users/wiki/12336/history?dataid=174009&dataid=170538 )

I provide unmodified bin and hex binaries of DiSlord's latest version in a branch of my clone, for version info just check the commit message - currently version 1.2.15:



These are the download links:

I have the H version 3.5 older software has small screen.. H4 larger screen
would be my choice for what we want to use it for. Other models have either
no case or more rugged case and have extended testing capabilities beyond
my scope. I'll dig into my notes a little later to send you more info. And
cautions regarding manufacturer.

I might as well put in my .02 cents worth. I am pleased with the new
Deeplec DeepVNA101. This is the current evolution of the VNA-F. It has the
4 inch screen and is more visible in the outdoor sun than others. The
biggest advantage of the DeepVNA101 is that it has a rotary encoder in
place of the rocker switch for adjusting values. This makes changing
parameters and frequency than most other VNA's in this price range. The
dynamic range has been improved over earlier versions. The big PLUS is the
ease of upgrading firmware. IN other units you have to work to get the unit
in the DFU mode and then load the new firmware. In the DeepVNA 101 you just
use the USB cable to plug into the computer, download the latest firmware
file from Deeplec, and place it in the root directory of the DeepVNA101.
Next turn the unit on and off and you are ready to go.

You can purchase the unit from Deeplec.com or even Amazon. If you order ANY
VNA from Amazon make sure you are getting and original and not a knock off
clone.



*Clyde K. Spencer*



On Wed, Oct 19, 2022 at 9:11 AM Lester Veenstra via groups.io <m0ycm=
[email protected]> wrote:

To be contrary; Not as low cost, but I would suggest the German/English
VNWA
I have them all, and on the bench I prefer to use the VNWA

Lester B Veenstra K1YCM M?YCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (REformed
CTM1)
lester@...

452 Stable Ln (HC84 RFD USPS Mail)
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Frank
Sent: Tuesday, October 18, 2022 3:32 PM
To: [email protected]
Subject: [nanovna-users] Which NANO VNA To Buy ?

I've been thinking about purchasing a VNA. I mainly will need it for HF
and VHF and I will only be using it once in a while for tuning a few
antennas I have in my attic.

I have been looking on Amazon and eBay and saw so many versions and also
so many different prices.

Saw V2, V4.3 and SA, H4 ? Its really been overwhelming. !

Any ideas on which one would be best for me ?

Frank