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On 6/28/23 3:30 PM, Pedro Madeira CT7AHV wrote:

Hello to all,
Thanks for all your inputs, I made a few searches and I saw the devices you
told.
Actually, I just need to work up to 150MHz, I build solid state amplifiers
and I need to tune the low pass filters. I also build antenna transformers,
Baluns, Ununs and RF chokes and need to measure them.
I have a nanoVNA S-A-A-2 which is useless because it doesn't measure Rs or
Xs independently in S21 mode, only measures impedance complex.

Isn't complex impedance Rs + Xs j?

But you said S21, which is also complex (although often displayed as magnitude and phase). But convertible to equivalent series R and X, with some math. There's been some discussion of this on the list, and it's not "instrument" dependent.



Tuning low

pass filters with this nanoVNA is also not possible because the measurements
are not accurate enough as my other VNA. I performed some comparisons and
the Transmission Loss in dB is very different, and yes I made proper
calibrations. The nanoVNA I have is just good enough to do SWR
measurements...

That seems odd.. how much rejection do you need to measure? (I'm assuming the passband isn't a problem). The little original NanoVNA does just fine at 60dB down, although I don't know that I'd want to commit to 1 dB uncertainty in the stop band.

The NanoVNA is probably not the right tool for aligning a 6 can diplexer for 2 meters.

My goal is to have a VNA independent of the use of a computer, that's why
I'm looking for a VNA with screen bigger than 3 inches! Which model should
be the most accurate? I know all these are Chinese devices, but maybe I can
find a reliable one for my works...

Well, yes - the tiny screen is a pain. I was checking some feedlines earlier this week outdoors and not only is the 3" screen hard to see, it's hard to take a picture of.

But if you're tuning something on a bench, it seems a computer isn't a deal breaker. I use a RPi to talk to a NanoVNA using NanoVNA-Saver, and it will display on as large a screen as you can plug in.

Thanks, best 73
Pedro Madeira
CT7AHV/C91AHV

Hello to all,
Thanks for all your inputs, I made a few searches and I saw the devices you
told.

Actually, I just need to work up to 150MHz, I build solid state amplifiers
and I need to tune the low pass filters. I also build antenna transformers,
Baluns, Ununs and RF chokes and need to measure them.

I have a nanoVNA S-A-A-2 which is useless because it doesn't measure Rs or
Xs independently in S21 mode, only measures impedance complex. Tuning low
pass filters with this nanoVNA is also not possible because the measurements
are not accurate enough as my other VNA. I performed some comparisons and
the Transmission Loss in dB is very different, and yes I made proper
calibrations. The nanoVNA I have is just good enough to do SWR
measurements...

My goal is to have a VNA independent of the use of a computer, that's why
I'm looking for a VNA with screen bigger than 3 inches! Which model should
be the most accurate? I know all these are Chinese devices, but maybe I can
find a reliable one for my works...


Thanks, best 73


Pedro Madeira
CT7AHV/C91AHV

I recently bought the SeeSii nanoVNA-H4 which has a 4" screen. I love the larger screen. It is useful up to 1.5 GHz, but my use for HF radio is just 3 to 30 MHz, plus VHF and UHF, so this is fine for me.

If you look at the nanoVNA menu structure map you will see that the H4 gets you some useful additional functions, including two more memory locations and 201, 301, and 401 sweep points options. The extra sweep points come at corresponding increase in sweep time, however.

As with all of the nanoVNA units, however, it is best to remember that the basic nanoVNA circuit design is open source, and you are getting what you pay for. Chief concern is component quality, shielding, and soldering.

73
Bob Rose "Zayde"
robert.rose@...
KN6UXD
DM13ld
SKCC 27222

Thanks Fran?ois for the response and taking the time. I wanted to put another plot on here, this is with another NanoVNAH4 I have and the outlier is in the middle of the sweep at ~130MHz. The calibration of the device does not get rid of it. I would like to know if there is a way to remove it experimentally or if anyone knows what the cause is.

On Wed, Jun 28, 2023 at 04:57 PM, EB4APL wrote:

Hi, I still keep a true GDO but I had nor used it for a long time.

When I built my Poor Ham Scalar Network Analyzer some years ago, I also
built a pickup coil wound in an old 35 mm film canister with a BNC
connector. I connect it to the Return Loss Bridge? and used it as a GDO
but much more convenient. When I got the nanoVNA I tested it with it and
the results are very good, you can measure the resonance of any? circuit
without physically connecting to it.? I uploaded some pictures to the
Photos section.

Ignacio

Nice job Ignacio. How many turns on your pickup coil?

I had to wind my pickup coil around the end of the inductor to get enough coupling for a response.

The dip is fairly close to the SRF estimated by Coil64, which was 15.58MHz.

Pictures attached.

--
Mike

The following photos have been uploaded to the Pickup coil ( /g/nanovna-users/album?id=287692 ) album of the [email protected] group.

* CAM01346r.jpg ( /g/nanovna-users/photofromactivity?id=3641350 )

*By:* EB4APL <eb4apl@...>



---

The following photos have been uploaded to the Pickup coil ( /g/nanovna-users/album?id=287692 ) album of the [email protected] group.

* CAM01348R.jpg ( /g/nanovna-users/photofromactivity?id=3641351 )

*By:* EB4APL <eb4apl@...>

Hi, I still keep a true GDO but I had nor used it for a long time.

When I built my Poor Ham Scalar Network Analyzer some years ago, I also built a pickup coil wound in an old 35 mm film canister with a BNC connector. I connect it to the Return Loss Bridge? and used it as a GDO but much more convenient. When I got the nanoVNA I tested it with it and the results are very good, you can measure the resonance of any? circuit without physically connecting to it.? I uploaded some pictures to the Photos section.

Ignacio

--
Este correo electrónico ha sido analizado en busca de virus por el software antivirus de Avast.
www.avast.com

The following photos have been uploaded to the Pickup coil ( /g/nanovna-users/album?id=287692 ) album of the [email protected] group.

* Pickup coil.jpg ( /g/nanovna-users/photofromactivity?id=3641345 )

*By:* EB4APL <eb4apl@...>

EB4APL <eb4apl@...> added the album Pickup coil ( /g/nanovna-users/album?id=287692 ) : A coil for using the nanoVNA as a GDO.

Hi Robert,

I have tried several times to send a message to cqxiegu, but I never got an answer.

I can't understand how a company like Xiegu can not respond to customer inquiries.

Other hams have contacted me who have had a similar problem to mine and have gone through an odyssey to get it fixed.

I hope I won't be forced to buy an icom 705, especially to avoid arguing with my wife....hi

Thanks and 73


Maurizio IW2GOB

Hi Pedro
This is the biggest screen I have seen so far:

73
Fredrik

Everitt and Anner, "Communication Engineering," Third Edition, McGraw-Hill, 1956, provide a general method (pages 330-331) for examining a mismatch between a source and load, such as a transmission line feeding an antenna. They factor the source and the load into series networks, one element of which in each case is Zo, the desired impedance.

They then use "Compensation Theorem A" from page 107, which states":

"Any impedance in a network (either linear or nonlinear) may be replaced by a generator of zero internal impedance, whose generated voltage at every instant is equal to the instantaneous potential difference produced across the replaced impedance by the current flowing through it."

Using this theorem, they replace the added network segments by voltage generators so that the resultant equivalent network consists of a matched source and load with added voltage generators to represent the voltages generated by the mismatch.

I applied this to the special case of the complex conjugate load in "More Octave for Complex Zo," QEX, September/October, 2019. In that case, no modification of the source voltage or impedance is needed and the complex conjugate load is replaced by a matched load (image impedance) in series with a reactance of opposite sign that is twice the value of the reactance of the complex conjugate load's reactance. That "extra" reactance may then be replaced by a complex voltage source of zero internal impedance that will be seen to be generating a voltage that corresponds to the value of the reflected signal.

73,

Maynard
W6PAP

nanovna v2plus4, lite vna64, nanovna h4, nanovna -F V2, etc etc

there are a handful of vna and vna v2 with 4 inch or 4.3 inch screens

i recommend to use one of the newer v2 models that go up to 3 or even up to 6 ghz cause the older models (1.5ghz) only have a clock up to 300mhz and above that (900mhz or 1.5ghz) is measured in harmonic mode (with reduced sensitivity and dynamic range) ... the newer v2 models are much better on the higher frequency area

maybe a lite64 is for you?? or a plus4 or ... a vna6000??? (a bit expensive in my view)

greetz sigi dg9bfc

ps an option is to buy a cheaper version and add a 4 inch screen to it ... just needs the fw for that bigger screen to be uploaded in the device

Am 28.06.2023 um 04:45 schrieb Pedro Madeira CT7AHV:

On 28/06/2023 03:45, Pedro Madeira CT7AHV wrote:

Hello to all
Recently I saw a nanoVNA somewhere with a bigger screen than the normal 3 inches.
Can someone tell me the model please?
Thanks in advance
73

Pedro,

There are several, but the "LiteVNA 64" has coverage up to 6 GHz and gets good reviews and comments here.



If 2 GHz is enough try the NanoVNA H4



Beware of clones....

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

Problem solved, TLW3 works ok.
Robert

Pedro,

most probably it was an nanoVNA-H4 (/g/nanovna-users/wiki#NanoVNA-H4)

There are other possibilities, but they are more expensive.

HTH, 73, Stay Safe,

Robin, G8DQX

Hello to all
Recently I saw a nanoVNA somewhere with a bigger screen than the normal 3 inches.
Can someone tell me the model please?

Thanks in advance
73

Pedro Madeira
CT7AHV/C91AHV

Ah, the old days! It's been 50 years since I've used a GDO (when G = grid!).

I'll give that a go, thanks.

--
Mike

On Tue, Jun 27, 2023 at 05:54 AM, Mike wrote:

I compared both methods of calibration, which I refer to as "screws" and
"crocs".

At around 72kHz, where the reactance is approximately 50R, both calibration
methods give an inductance of 108uH. However, the SRF was 7.4MHz for "screws"
and 12.9MHz for "crocs".

I then repeated the measurement with a different VNA, an FA-VA5. This gave
L=110.7uH for "screws" and 110.5uH for "crocs". The SRF was 6.38MHz for
"screws" and 6.45MHz for "crocs".

I can accept the difference in L between the two devices but can't decide
which one is giving me the most accurate SRF.

With a 110 uH coil it takes 4.2 pF to resonate at 7.4 MHz. and 1.4 pF to resonate at 12.9 MHz. That is a difference of 2.8 pF which is not much.

One way to get to the bottom of this is to short the terminals of the coil together and then "grid dip" it like the old days. You can do this with the NanoVNA by making a pickup coil at the end of a short connecting cable. Calibrate over 5 to 15 MHz. in the usual manner. Set the trace to S11 Log (Return Loss setting) Then attach the pickup coil to the NanoVNA and place the 110 uh coil and the pickup coil in parallel a short distance apart. Look for a dip in the trace. Keep moving the coil further away until the dip has just about disappeared. Now move a marker to the dip and the frequency should be very close to the SRF.

Roger

On Tue, Jun 27, 2023 at 04:23 PM, Robert wrote:

I have a PC with Windows 7 Pro SP1 32bit (German).
C:\windows\SysWOW64 does not exist on my OS, and your batch file reports an
error.
On my 2 other Win10 64bit PCs TLW3 works ok after running TLW3-Install.bat.
I get the Error 339 when I exit TLW3.

My batch file is for 64 bit systems only.

Try manually copying TeeChart5.ocx to C:\WINDOWS\system32

Then run TLW3.exe

Roger