Dear OM, I'm interested about various measurements with NanoVNA but now I'm fighting with some fundamental questions not related only to nano VNA. but still unable to find answers, even after reading a lot of articles (for example k9yc, palomar engineers, and not only...)
- when I will try to determine ferrite core material by inductance and AL value, how can I be sure about right frequency for inductance? inductance could vary with frequency (various permeability) and then my AL value calculation could be wrong.
- I read somewhere that chokes need higher AL value then transformers. Why chokes requires higher AL value and transformers lower? It is because in chokes big AL value means high inductance with small amount of winding and wire and then high impedance for common mode currents with good efficiency?
Many thanks for answers, hope I will find an answer even when it is not simple topic ?
sources which I used:
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Re: nanovna-saver/displayed charts/S11 R/¦Ø & X/¦Ø (?? / Hz)
My question of F4HTQ having remained unanswered, I appeal to you again.
Question 1
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I do not understand one of the graphs of Nanovna-Saver: S11 R/¦Ø & X/¦Ø
I don't understand what it wants to represent, nor the units. In addition there are two curves. It does not seem to me that the values ??are returned to the data of the markers. Basically I don't understand anything.
Question 2
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I had the bad idea to check the overall operation by putting under test, between 1 MHz and 10 MHz, a simplistic circuit made up of a 720 PF capacitor with a resistance of 51 ¦¸.
If the value of the series resistance is almost constant, this is not the case with the value of the series capacitor. I changed the type of capacitor (mica / ceramic) I get exactly the same values. I even observe a resonance at 20.7 MHz, frequency where the serial impedance is worth 50.2+J1.74.
Why does the bridge produce this aberrant result.
73 And thank you for your help
--
F1AMM (Fran?ois)
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Re: Using a nanoVNA as a passive receiver
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Re: Perfect SWR with dummy load, but huge with antenna
That was my first thought when i have seen your first post.... Antenna is rp-sma
.... You also should by some extenders (male female sma)....
Sma socket may wear out after extensive usage... And its easier to just replace the extender... Call it a socket saver
Dg9bfc sigi
Am 03.07.2022 09:20 schrieb Lucian <lucian@...>:
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Thanks, but you were too quick to dismiss the human factor..
It wasn't until this morning that I realised the antenna is rp-sma female
and the nanovna is sma female.. They will screw in perfectly, yet no core
contact... facepalm.
I'll need to buy some adapters.
Have a nice day!
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Re: Perfect SWR with dummy load, but huge with antenna
Thanks, but you were too quick to dismiss the human factor..
It wasn't until this morning that I realised the antenna is rp-sma female and the nanovna is sma female.. They will screw in perfectly, yet no core contact... facepalm.
I'll need to buy some adapters.
Have a nice day!
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Re: Perfect SWR with dummy load, but huge with antenna
Willing to bet you have a strong, or many, interfering signals in the
passband. Point your test antenna straight upward and see if anything
changes. However, if you have additional strong signals in the area, you
will be unable to determine the SWR of your test antenna.
Dave - W?LEV
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On Sun, Jul 3, 2022 at 1:01 AM Lucian <lucian@...> wrote: Hi,
Just bought a Nanovna-h (0.4.5-4-g96e7efe firmware) and calibrated it,
tuned the display to only show the SWR, however while I am getting a
perfect SWR of 1 with the dummy load, I get a SWR in the hundreds or
thousands with the antenna.
The antenna is a commercial and tested LoRA 868 MHz one and this is indeed
what I am testing for, yet the Nanovna reports huge SWR.
Did I buy a dud or am I looking at the wrong things?
A few pictures here to see what I mean:
Thanks!
-- *Dave - W?LEV* *Just Let Darwin Work*
--
Dave - W?LEV
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Perfect SWR with dummy load, but huge with antenna
Hi,
Just bought a Nanovna-h (0.4.5-4-g96e7efe firmware) and calibrated it, tuned the display to only show the SWR, however while I am getting a perfect SWR of 1 with the dummy load, I get a SWR in the hundreds or thousands with the antenna.
The antenna is a commercial and tested LoRA 868 MHz one and this is indeed what I am testing for, yet the Nanovna reports huge SWR.
Did I buy a dud or am I looking at the wrong things?
A few pictures here to see what I mean:
Thanks!
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One seldom achieves the "advertised" or modeled pattern, especially at HF
frequencies. VHF, UHF, and ?waves are whole different stories. HF
patterns rarely conform to expected results except for installations done
by Uncle with unlimited budget (just us taxpayers!). So, don't sweat the
pattern modification. Even the "expected" pattern is likely not thereas
assumed.
And with only 28 dB isolation between the two antennas, disconnect one from
any receivers while transmitting on the other. 28 dB down from 100-watts
is still roughly 160 mW. I sure would not input that much power into any
receiver I own!
Dave - W?LEV
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On Sat, Jul 2, 2022 at 7:15 PM WB2UAQ <pschuch@...> wrote: Did a coupling test between two antennas and it was interesting to see how
the impedance looking into one antenna was impacted when leaving one of
the antennas open, shorted and terminated in 50 ohms. With about 28 dB
between antennas I would see a change of a about 0.5 to 1 ohm. Could be
an indication of how one antenna impacts the radiation pattern of the
other. The energy reflected by one of the antennas is phase shifted by
180 degrees between a short and an open condition. At 28 dB of isolation
I bet there is little pattern change. Something to think about.
-- *Dave - W?LEV* *Just Let Darwin Work*
--
Dave - W?LEV
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Did a coupling test between two antennas and it was interesting to see how the impedance looking into one antenna was impacted when leaving one of the antennas open, shorted and terminated in 50 ohms. With about 28 dB between antennas I would see a change of a about 0.5 to 1 ohm. Could be an indication of how one antenna impacts the radiation pattern of the other. The energy reflected by one of the antennas is phase shifted by 180 degrees between a short and an open condition. At 28 dB of isolation I bet there is little pattern change. Something to think about.
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Re: Using a nanoVNA as a passive receiver
Thank you very much for the precise answer.
For the TinySA, I read:
Manually selectable resolution filters of 3, 10, 30, 100, 300, 600 kHz. Automatic selection of one of 57 resolution filters.
What do these 57 filters correspond to ?
Does this type of device make it possible to evaluate the IMD (Intermodulation Distortion) produced by an SSB power amplifier where it seems to me that a much finer resolution than 3 kHz is needed ?
73
--
Fran?ois
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-----Message d'origine----- De la part de Larry AC9OX Envoy¨¦ : samedi 2 juillet 2022 13:32
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Re: Using a nanoVNA as a passive receiver
Good Morning,
Yes, the tinySA has computer control application:
Larry
AC9OX
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Re: Using a nanoVNA as a passive receiver
On 02/07/2022 10:41, Siegfried Jackstien wrote: A similar device is the rf explorer.. And THAT can be driven from pc
Or just use an rtl dongle
From nuts about nets there is a free soft that was mainly made for the explorer but can also drive an rtl stick
It let the rtl scan over a given area in 2 megs steps an stitches that together to your sweep scan
Akso other scanning soft is available fir the rtl (and a few other sdr)
.... So with pc use you have a few options..
Greetz sigi dg9bfc If you have a Pluto (possibly RTL-SDR): For the RTL and others: 73, David GM8ARV -- SatSignal Software - Quality software for you Web: Email: david-taylor@... Twitter: @gm8arv
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Re: Using a nanoVNA as a passive receiver
A similar device is the rf explorer.. And THAT can be driven from pc
Or just use an rtl dongle
From nuts about nets there is a free soft that was mainly made for the explorer but can also drive an rtl stick
It let the rtl scan over a given area in 2 megs steps an stitches that together to your sweep scan
Akso other scanning soft is available fir the rtl (and a few other sdr)
.... So with pc use you have a few options..
Greetz sigi dg9bfc
Am 02.07.2022 07:06 schrieb F1AMM <18471@...>:
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Hello
Evan Main wrote: A better tool is the TinySA.
Is there software like nanovna-saver that can drive this TinySA from a PC?
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Re: Usinf the NanoVNA-H4 to identify ferrite cores
Read this one.
I've gone the path :-)
73
Arie PA3A
Op 1-7-2022 om 20:46 schreef n4cla@...:
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Good afternoon. I am not sure but I don't think I have seen this mentioned as yet another tool for the NanoVNA. Can the Nano be used to help identify anything about any of the cores that are sold by Amadon or Fairite? I have many unidentified cores and would like to try to identify them as well as many others out there.
Thanks
Fred - n4cla
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Re: Using a nanoVNA as a passive receiver
Hello
Evan Main wrote: A better tool is the TinySA.
Is there software like nanovna-saver that can drive this TinySA from a PC?
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Re: nanovna-saver/displayed charts/S11 R/¦Ø & X/¦Ø (?? / Hz)
Hello
Regarding my initial question "S11 R/¦Ø & X/¦Ø (?¦¸ / Hz)" I contacted F4HTQ directly, who answered me, but I don't have the technical answer yet.
I restored the various formulas allowing to calculate the values displayed by nanovna-saver, I take advantage of the subject and your skills to ask other questions.
1/ What is the native measurement performed by the bridge. I see that we can recalculate everything from S11 (in the form a+jb), value that we find in the .S1P files
6802488 0.4113950308366892 -0.670538673974817
or in .CAL files
# Hz ShortR ShortI OpenR OpenI LoadR LoadI ThroughR ThroughI IsolationR IsolationI
3/ How is calculated the Quality factor appearing in the data of the marker; I don't even see its practical significance.
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Re: Usinf the NanoVNA-H4 to identify ferrite cores
Please see the attachments as well. If one wants to test a single ferrite
toroid with no windings, I have a 1/4-inch rod that fits between the
alligator clips with the toroid in place.
[image: image.png]
[image: image.png]
Dave - W?LEV
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On Fri, Jul 1, 2022 at 10:41 PM Dave (NK7Z) <dave@...> wrote: Anyone have a photo of their Ferrite text fixture?
73, and thanks,
Dave (NK7Z)
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 7/1/22 13:50, W0LEV wrote:
There is a tutorial which I have referred to in the past for such a purpose
on the Fair-Rite www site.
Look under "Technical Resources" at the bottom of this folder. You will
find an excellent presentation there on how to determine what you have in
terms of ferrite cores. You can use the NANOVNA at the bottom end of its
frequency coverage to measure the inductance which you will need. What is
required:
1) The dimensions of the core / toroid
2) The measured inductance with a known number of turns (it will guide you
in this respect).
3) The number of turns on the toroid
4) The frequency of measurement (don't remember if this is necessary)
Then there is an applet you input these values into which comes up with the
material. It's golden.
Dave - W?LEV
On Fri, Jul 1, 2022 at 6:46 PM <n4cla@...> wrote:
Good afternoon. I am not sure but I don't think I have seen this
mentioned as yet another tool for the NanoVNA. Can the Nano be used to
help identify anything about any of the cores that are sold by Amadon or
Fairite? I have many unidentified cores and would like to try to identify
them as well as many others out there.
Thanks
Fred - n4cla
-- *Dave - W?LEV* *Just Let Darwin Work*
--
Dave - W?LEV
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Re: Usinf the NanoVNA-H4 to identify ferrite cores
Anyone have a photo of their Ferrite text fixture?
73, and thanks,
Dave (NK7Z)
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
toggle quoted message
Show quoted text
On 7/1/22 13:50, W0LEV wrote: There is a tutorial which I have referred to in the past for such a purpose
on the Fair-Rite www site.
Look under "Technical Resources" at the bottom of this folder. You will
find an excellent presentation there on how to determine what you have in
terms of ferrite cores. You can use the NANOVNA at the bottom end of its
frequency coverage to measure the inductance which you will need. What is
required:
1) The dimensions of the core / toroid
2) The measured inductance with a known number of turns (it will guide you
in this respect).
3) The number of turns on the toroid
4) The frequency of measurement (don't remember if this is necessary)
Then there is an applet you input these values into which comes up with the
material. It's golden.
Dave - W?LEV
On Fri, Jul 1, 2022 at 6:46 PM <n4cla@...> wrote:
Good afternoon. I am not sure but I don't think I have seen this
mentioned as yet another tool for the NanoVNA. Can the Nano be used to
help identify anything about any of the cores that are sold by Amadon or
Fairite? I have many unidentified cores and would like to try to identify
them as well as many others out there.
Thanks
Fred - n4cla
|
Re: Usinf the NanoVNA-H4 to identify ferrite cores
There is a tutorial which I have referred to in the past for such a purpose
on the Fair-Rite www site.
Look under "Technical Resources" at the bottom of this folder. You will
find an excellent presentation there on how to determine what you have in
terms of ferrite cores. You can use the NANOVNA at the bottom end of its
frequency coverage to measure the inductance which you will need. What is
required:
1) The dimensions of the core / toroid
2) The measured inductance with a known number of turns (it will guide you
in this respect).
3) The number of turns on the toroid
4) The frequency of measurement (don't remember if this is necessary)
Then there is an applet you input these values into which comes up with the
material. It's golden.
Dave - W?LEV
toggle quoted message
Show quoted text
On Fri, Jul 1, 2022 at 6:46 PM <n4cla@...> wrote: Good afternoon. I am not sure but I don't think I have seen this
mentioned as yet another tool for the NanoVNA. Can the Nano be used to
help identify anything about any of the cores that are sold by Amadon or
Fairite? I have many unidentified cores and would like to try to identify
them as well as many others out there.
Thanks
Fred - n4cla
-- *Dave - W?LEV* *Just Let Darwin Work*
--
Dave - W?LEV
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Re: Usinf the NanoVNA-H4 to identify ferrite cores
We can analyze the characteristics of the ferrites in the drawers with a nanoVNA device and a nanoVNA-Saver program. These "curves" should then be compared with the curves given by the manufacturers. You can see such curves, e.g. here: The first ferrite measurements with the nanoVNA were discussed by forum members here: /g/nanovna-users/message/6996 and in subsequent discussions. ( /g/nanovna-users/topic/nanovna_saver_0_2_0/54247421?p=Created,,,20,1,20,0&jump=1) NanoVNA Sorts Unknown Ferrite Suppression Beads So whoever is interested in the topic can do it. nanoVNA-Saver -> Display setup -> S11 with R/¦Ø & X/¦Ø (?¦¸/Hz) selection. -- Gyula HA3HZ ( )
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Larry McElhiney
David J Taylor
Arie Kleingeld PA3A
HA3HZ