NanoVNA SAA-N2 giving incorrect values below 5 mhz

Robert Cartier 2023/01/16 16:09

I just finished comparing my AURSINC nanovna-h against my new AURSINC NanoVNA SAA-2N V2.2 ( https://www.amazon.com/gp/product/B08G4GXTKK/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1 )
and found that the readings below 5 mhz appear to be invalid. I am testing against an antenna that is going thru
a UNUN 9:1.

Both a RiGExpert AA-230 and the nanovna-h appear to depict the SWR accurately but the SAA-2N shows an values of 10
and the others are showing 4.

Green = Rigexpert
Red = nanovna-h
Orange = SAA-2N

It seems to start tracking a little closer once I get past 7 mhz

Any ideas. is the unit defective or having issues with the unun 9:1 where as the others arent ??

UNUN-9 comparison.png

nanov2support 2023/01/16 23:37

Hi, unfortunately the version you have is a clone of an outdated design. Because of the parts shortage the original V2 design has become much more costly to produce, so most clones have now switched to alternative parts without the correct ratings. If you bought it from Amazon you may be able to return it.

Please see here for where to find an original NanoVNA V2: https://nanorfe.com/nanovna-v2.html

We are currently on holiday but will resume taking orders in about two weeks.

Thanks

Glenn Little 2023/01/17 16:42

I would be very surprised if either responded to a 5 milli-hertz signal,
unless, you used the wrong prefix and meant 5 Mega-hertz.

Not understanding the prefixes, or improperly using them can lead to a
lot of confusion.

Glenn

On 1/16/2023 7:09 PM, Robert Cartier via groups.io wrote:
> I just finished comparing my AURSINC nanovna-h against my new AURSINC
> NanoVNA SAA-2N V2.2
> <https://www.amazon.com/gp/product/B08G4GXTKK/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1>
> and found that the readings below 5 mhz appear to be invalid. I am
> testing against an antenna that is going thru
> a UNUN 9:1.
>
> Both a RiGExpert AA-230 and the nanovna-h appear to depict the SWR
> accurately but the SAA-2N shows an values of 10
> and the others are showing 4.
>
> Green = Rigexpert
> Red = nanovna-h
> Orange = SAA-2N
>
> It seems to start tracking a little closer once I get past 7 mhz
>
> Any ideas. is the unit defective or having issues with the unun 9:1
> where as the others arent ??
>

--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIVwb4uiv@arrl.net AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

WA2TP 2023/01/18 10:37

Do you have any am or fm broadcast stations that are within 15 miles?
You could be overloading one of the units.
Perhaps the 2n doesn’t do as good of a job in the presence of strong RF

On Jan 18, 2023, at 12:00 AM, Glenn Little <glennmaillist@bellsouth.net> wrote:

I would be very surprised if either responded to a 5 milli-hertz signal, unless, you used the wrong prefix and meant 5 Mega-hertz.

Not understanding the prefixes, or improperly using them can lead to a lot of confusion.

Glenn

On 1/16/2023 7:09 PM, Robert Cartier via groups.io wrote:
I just finished comparing my AURSINC nanovna-h against my new AURSINC NanoVNA SAA-2N V2.2 <https://www.amazon.com/gp/product/B08G4GXTKK/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1>
and found that the readings below 5 mhz appear to be invalid. I am testing against an antenna that is going thru
a UNUN 9:1.

Both a RiGExpert AA-230 and the nanovna-h appear to depict the SWR accurately but the SAA-2N shows an values of 10
and the others are showing 4.

Green = Rigexpert
Red = nanovna-h
Orange = SAA-2N

It seems to start tracking a little closer once I get past 7 mhz

Any ideas. is the unit defective or having issues with the unun 9:1 where as the others arent ??

--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@arrl.net<mailto:wb4uiv@arrl.net> AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

W0LEV 2023/01/18 17:57

Once again:

M = Mega = 10^6
m = milli = 10^-6

Correct abbreviations are required in engineering and should be even in
amateur radio which is steeped in good engineering practices.

Dave - WØLEV

On Wed, Jan 18, 2023 at 12:58 PM WA2TP <myis300@hotmail.com> wrote:

> Do you have any am or fm broadcast stations that are within 15 miles?
> You could be overloading one of the units.
> Perhaps the 2n doesn’t do as good of a job in the presence of strong RF
>
> On Jan 18, 2023, at 12:00 AM, Glenn Little <glennmaillist@bellsouth.net>
> wrote:
>
> I would be very surprised if either responded to a 5 milli-hertz
> signal, unless, you used the wrong prefix and meant 5 Mega-hertz.
>
> Not understanding the prefixes, or improperly using them can lead to a lot
> of confusion.
>
> Glenn
>
> On 1/16/2023 7:09 PM, Robert Cartier via groups.io wrote:
>
> I just finished comparing my AURSINC nanovna-h against my new AURSINC
> NanoVNA SAA-2N V2.2
> <https://www.amazon.com/gp/product/B08G4GXTKK/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1>
> and found that the readings below 5 mhz appear to be invalid. I am testing
> against an antenna that is going thru
> a UNUN 9:1.
>
> Both a RiGExpert AA-230 and the nanovna-h appear to depict the SWR
> accurately but the SAA-2N shows an values of 10
> and the others are showing 4.
>
> Green = Rigexpert
> Red = nanovna-h
> Orange = SAA-2N
>
> It seems to start tracking a little closer once I get past 7 mhz
>
> Any ideas. is the unit defective or having issues with the unun 9:1 where
> as the others arent ??
>
>
> --
> -----------------------------------------------------------------------
> Glenn Little ARRL Technical Specialist QCWA LM 28417
> Amateur Callsign: WB4UIV wb4uiv@arrl.net AMSAT LM 2178
> QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
> "It is not the class of license that the Amateur holds but the class
> of the Amateur that holds the license"
>
>
>
>

--
*Dave - WØLEV*

Ken Sejkora 2023/01/19 06:45

Absolutely correct, Dave. However, I’m not sure if someone who easily confuse a lower-case ‘m’ with an upper-case ‘M’ will understand the semi-scientific notation of 10^6 vs 10^-6. Easier to understand and less confusing by stating it as:

M = Mega = 1,000,000 = 10^6 = 1E+6
m = milli = 0.001 = 10^-3 = 1E-3

Also, your notation for milli as 10^-6 should be really 10^-3. Notation as 10^-6 would actually be micro, or 0.000001, which carries an abbreviation of lower-case ‘u’, or more correctly the lower-case Greek letter ‘Mu’. For example, 1 µ-meter = 1 micrometer = 0.000001 meter. This is also more commonly referred to as a micron.

One can ‘type’ a lower case Greek Mu (µ) by holding down the ALT-key and typing 230 on the numeric pad on the keyboard, or inserting the appropriate corresponding symbol from the Symbol font. Here are a few other useful ALT-numeric keypad notations:

Alt228 = Σ (summation)
Alt234 = Ω (ohms)
Alt236 = ∞ (infinity)
Alt241 = ± (plus/minus)
Alt242 = ≥ (greater than or equal to)
Alt243 = ≤ (less than or equal to)
Alt246 = ÷ (division sign)
Alt247 = ≈ (approximate)
Alt248 = ° (degrees)

Of course, I know you fully understand all of this Dave, but there are others out there in the discussion group that might not.

Have a great day.

Ken -- WBØOCV

From: W0LEV
Sent: Thursday, January 19, 2023 02:09 AM
To: NanoVNAV2@groups.io
Subject: Re: [nanovnav2] NanoVNA SAA-N2 giving incorrect values below 5 mhz

Once again:

M = Mega = 10^6
m = milli = 10^-6

Correct abbreviations are required in engineering and should be even in amateur radio which is steeped in good engineering practices.

Dave - WØLEV

Stephen Laurence 2023/01/19 03:49

Errrrrr...

Surely m is milli which is a thousandth as in millimetre, NOT one millionth (-is nano not a millionth?)
c is a hundredth as in centimetre

Please correct if I am wrong

Stephen Laurence. G7PSZ

Ken Sejkora 2023/01/19 07:54

Hi Stephen,

Certainly lower-case ‘m’ is milli, one-thousandth. One-millionth is ‘micro’. ‘Nano’ is one-billionth, or 0.000000001, or 10^-9 or 1E-9.

Standard engineering notation works in multiplier-increments of 1000. Here’s a table that lists the common, and some uncommon, abbreviations. Note that the non-standard abbreviations in the middle of the table which deviate from the 1000-rule are not listed in bold text:

Ken – WBØOCV

From: Stephen Laurence
Sent: Thursday, January 19, 2023 07:40 AM
To: NanoVNAV2@groups.io
Subject: Re: [nanovnav2] NanoVNA SAA-N2 giving incorrect values below 5 mhz

Errrrrr...

Surely m is milli which is a thousandth as in millimetre, NOT one millionth (-is nano not a millionth?)
c is a hundredth as in centimetre

Please correct if I am wrong

Stephen Laurence. G7PSZ

C83928D0BD92414EA987B525AF8AF964.jpg

F169BE85B0AF423B830F870E273093B6.png

Dave Daniel 2023/01/19 08:03

Yes.

The correct SI prefix for 10^-6 is “micro”, symbolized by the Greek letter mu
(“μ”).

DaveD

> On Jan 19, 2023, at 07:40, Stephen Laurence <Gaslaurence@gmail.com> wrote:
>
>

> Errrrrr...
>
> Surely m is milli which is a thousandth as in millimetre, NOT one millionth
(-is nano not a millionth?)
> c is a hundredth as in centimetre
>
> Please correct if I am wrong
>
> Stephen Laurence. G7PSZ

_._,_._,_

* * *

Robert Cartier 2023/01/19 08:09

Guys

it was just entered in the emaill. it was entered correctly in nanovna-saver

Thanks all

Robert Cartier
kd1jg@icloud.com

- Show quoted text -

j.zietlow 2023/01/19 07:52

Check again Dave, milli is 10^-3 😊

John K9WIC

Marc Nordquest 2023/01/19 11:01

m=milli, or one thousandth, or 10^-3

On Thu, Jan 19, 2023, 2:09 AM W0LEV <davearea51a@gmail.com> wrote:

- Show quoted text -

W0LEV 2023/01/19 17:35

Thanks, Ken. Especially for the correction on milli being 10E-3!

I use scientific notation all the time and assume others who have gone
through high school also have a knowledge of logarithms. But, then, I'm a
total nerd and techie from the age of maybe 5. Now 76 and all this is a
part of my life (and profession).

I'd ask just one question: how did they get their licenses without
learning this?

Enough for excuses.

Dave - WØLEV

On Thu, Jan 19, 2023 at 12:40 PM Ken Sejkora <kjsejkora@comcast.net> wrote:

> Absolutely correct, Dave. However, I’m not sure if someone who easily
> confuse a lower-case ‘m’ with an upper-case ‘M’ will understand the
> semi-scientific notation of 10^6 vs 10^-6. Easier to understand and less
> confusing by stating it as:
>
>
>
> M = Mega = 1,000,000 = 10^6 = 1E+6
>
> m = milli = 0.001 = 10^-3 = 1E-3
>
>
>
> Also, your notation for milli as 10^-6 should be really 10^-3. Notation
> as 10^-6 would actually be micro, or 0.000001, which carries an
> abbreviation of lower-case ‘u’, or more correctly the lower-case Greek
> letter ‘Mu’. For example, 1 µ-meter = 1 micrometer = 0.000001 meter. This
> is also more commonly referred to as a micron.
>
>
>
> One can ‘type’ a lower case Greek Mu (µ) by holding down the ALT-key and
> typing 230 on the numeric pad on the keyboard, or inserting the appropriate
> corresponding symbol from the Symbol font. Here are a few other useful
> ALT-numeric keypad notations:
>
>
>
> Alt228 = Σ (summation)
>
> Alt234 = Ω (ohms)
>
> Alt236 = ∞ (infinity)
>
> Alt241 = ± (plus/minus)
>
> Alt242 = ≥ (greater than or equal to)
>
> Alt243 = ≤ (less than or equal to)
>
> Alt246 = ÷ (division sign)
>
> Alt247 = ≈ (approximate)
>
> Alt248 = ° (degrees)
>
>
>
> Of course, I know you fully understand all of this Dave, but there are
> others out there in the discussion group that might not.
>
>
>
> Have a great day.
>
>
>
> Ken -- WBØOCV
>
>
>
> *From: *W0LEV <davearea51a@gmail.com>
> *Sent: *Thursday, January 19, 2023 02:09 AM
> *To: *NanoVNAV2@groups.io
> *Subject: *Re: [nanovnav2] NanoVNA SAA-N2 giving incorrect values below 5
> mhz
>
>
>
> Once again:
>
>
>
> M = Mega = 10^6
>
> m = milli = 10^-6
>
>
>
> Correct abbreviations are required in engineering and should be even in
> amateur radio which is steeped in good engineering practices.
>
>
>
> Dave - WØLEV
>
>
>
>
>

--
*Dave - WØLEV*

Jim Lux 2023/01/19 09:56

On 1/19/23 4:54 AM, Ken Sejkora wrote:
> Hi Stephen,
>
> Certainly lower-case ‘m’ is milli, one-thousandth. One-millionth is
> ‘micro’. ‘Nano’ is one-billionth, or 0.000000001, or 10^-9 or 1E-9.
>
> Standard engineering notation works in multiplier-increments of 1000.
> Here’s a table that lists the common, and some uncommon, abbreviations.
> Note that the non-standard abbreviations in the middle of the table
> which deviate from the 1000-rule are not listed in bold text:
>

As a practical matter, in emails, particularly from handheld devices,
the whole m/M thing gets fouled up a lot. I figure, as long as it
communicates. Usually, it's context - few people work in milliHertz -
(Seismologists, Earth Dynamics, maybe some folks worried about random
processes in oscillators - millihertz offsets from the carrier as phase
noise vs Allan Deviation as time - they're subtly different).

Another one is using uF instead of the actual "micro" character. some
folks use mF (milliFarad is a very unusual unit to use) which I would
discourage.

But ultimately, if it communicates, I'd say it's ok.

Jim Lux 2023/01/19 15:12

On 1/19/23 9:35 AM, W0LEV wrote:
> Thanks, Ken. Especially for the correction on milli being 10E-3!
>
> I use scientific notation all the time and assume others who have gone
> through high school also have a knowledge of logarithms. But, then, I'm
> a total nerd and techie from the age of maybe 5. Now 76 and all this is
> a part of my life (and profession).
>
> I'd ask just one question: how did they get their licenses without
> learning this?

There aren't freehand or typed responses on the test. The test
questions, and answers, would generally have the correct case/symbology.

Realistically, too, a ham isn't going to ever work in millihertz (except
perhaps in the FMT), so if they see mHz (or mhz, or MHZ) they are going
to interpret it as MHz.

FWIW that whole Alt-digits thing only works on Windows, eh?

For those of us using an ASCII only keyboard, or who have displays that
don't understand extended character sets, we don't get mu or other fancy
characters. For those communicating in Morse code, I'll venture few use
the greek letters, nor lower case (so instead of kHz, it's KHZ),
although I believe there actually are Morse symbols for those.

<grin>

Ken Sejkora 2023/01/20 06:41

It takes a trillion (10^12) microphones to make one megaphone.

And don’t make mistakes… it takes a quintillion (10^18) attoboys to offset one mistake! 😉

From: Jim Lux
Sent: Friday, January 20, 2023 01:28 AM
To: NanoVNAV2@groups.io
Subject: Re: [nanovnav2] NanoVNA SAA-N2 giving incorrect values below 5 mhz

On 1/19/23 9:35 AM, W0LEV wrote:
> Thanks, Ken. Especially for the correction on milli being 10E-3!
>
> I use scientific notation all the time and assume others who have gone
> through high school also have a knowledge of logarithms. But, then, I'm
> a total nerd and techie from the age of maybe 5. Now 76 and all this is
> a part of my life (and profession).
>
> I'd ask just one question: how did they get their licenses without
> learning this?

There aren't freehand or typed responses on the test. The test
questions, and answers, would generally have the correct case/symbology.

Realistically, too, a ham isn't going to ever work in millihertz (except
perhaps in the FMT), so if they see mHz (or mhz, or MHZ) they are going
to interpret it as MHz.

FWIW that whole Alt-digits thing only works on Windows, eh?

For those of us using an ASCII only keyboard, or who have displays that
don't understand extended character sets, we don't get mu or other fancy
characters. For those communicating in Morse code, I'll venture few use
the greek letters, nor lower case (so instead of kHz, it's KHZ),
although I believe there actually are Morse symbols for those.

<grin>

W0LEV 2023/01/20 17:52

Jim, I went through college in physics. If I had used lower case "m" for
MegaHertz, I would have gotten zero credit for that improper abbreviation.
Even in "amateur" radio, I don't believe there is any place for these sort
of errors and oversights (forgiveness?).

If any ham had taken chemistry in HS, he/she would be intimately aware of
scientific notation. For example, Avogadro's Number: 6.02(2...?)E+23
molecules/mole. Further: I had logarithms in HS algebra. But I was doing
the decibel well before that.

This won't go anywhere, but it just grates me with 60-grit garnet paper to
view these errors.

Dave - WØLEV

On Fri, Jan 20, 2023 at 6:28 AM Jim Lux <jimlux@earthlink.net> wrote:

> On 1/19/23 9:35 AM, W0LEV wrote:
> > Thanks, Ken. Especially for the correction on milli being 10E-3!
> >
> > I use scientific notation all the time and assume others who have gone
> > through high school also have a knowledge of logarithms. But, then, I'm
> > a total nerd and techie from the age of maybe 5. Now 76 and all this is
> > a part of my life (and profession).
> >
> > I'd ask just one question: how did they get their licenses without
> > learning this?
>
> There aren't freehand or typed responses on the test. The test
> questions, and answers, would generally have the correct case/symbology.
>
> Realistically, too, a ham isn't going to ever work in millihertz (except
> perhaps in the FMT), so if they see mHz (or mhz, or MHZ) they are going
> to interpret it as MHz.
>
> FWIW that whole Alt-digits thing only works on Windows, eh?
>
> For those of us using an ASCII only keyboard, or who have displays that
> don't understand extended character sets, we don't get mu or other fancy
> characters. For those communicating in Morse code, I'll venture few use
> the greek letters, nor lower case (so instead of kHz, it's KHZ),
> although I believe there actually are Morse symbols for those.
>
> <grin>
>
>
>
>
>
>
>
>

--
*Dave - WØLEV*

Jim Allyn - N7JA 2023/01/20 12:14

On Thu, Jan 19, 2023 at 10:28 PM, Jim Lux wrote:

>
> Realistically, too, a ham isn't going to ever work in millihertz (except
> perhaps in the FMT), so if they see mHz (or mhz, or MHZ) they are going to
> interpret it as MHz.

People tell me I take things too literally. If somebody writes mHz, which is the abbreviation for millihertz, I am going to assume they mean millihertz. If they mean megahertz, they should use the appropriate abbreviation, which is MHz.

I confess I have been known to use uF for microfarad, rather than taking the time to look up how to do a µ on my system. (I just tried what I thought was the most likely [Compose key, m, u], and it worked.) And when to capitalize Hertz? Only at the beginning of a sentence or when referring to the person, Heinrich Hertz. According to the National Institute of Science and Technology (NIST), "When spelled out in full, unit names are treated like ordinary English nouns. Thus the names of all units start with a lower-case letter, except at the beginning of a sentence or in capitalized material such as a title. In keeping with this rule, the unit symbols for Ampere is a capitalized "A" and Volt is capitalized "V" because both unit names are based on the names of scientists." (I would argue that ampere and volt probably should NOT have been capitalized in that sentence.)

David J Taylor 2023/01/21 07:17

On 20/01/2023 20:14, Jim Allyn - N7JA wrote:
> On Thu, Jan 19, 2023 at 10:28 PM, Jim Lux wrote:
>
> Realistically, too, a ham isn't going to ever work in millihertz (except
> perhaps in the FMT), so if they see mHz (or mhz, or MHZ) they are going to
> interpret it as MHz.

I've just been comparing two 10 MHz GPSDO where the offset is about 3 mHz - one
cycle in about 300 seconds. I thought that some frequency measuring tests were
organised (ARRL?) where mHz mattered?

Ah, that's what FMT means!

David GM8ARV
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv

Siegfried Jackstien 2023/01/21 16:08

and then there are there "chatting rules" used in forums or newsgroups
where CAPITALIZE is seen as "shouting" ... or can be used to

let A MAJOR THING stand out in the text :-)

lets not beat that dead horse anymore ... we can all imagine that the
user meant MEGAHERTZ not milliHERTZ (uups .. was that now shouting?!?)

have fun and do not overcomplicate things

all was about the SAA2N (another typo found?!?) and millihertz is sure
not for an antenna we would use

DG9BFC sigi

Am 20.01.2023 um 21:14 schrieb Jim Allyn - N7JA:

- Show quoted text -

Raj vu2zap 2023/01/22 12:20

David,

I feed two oscillators into a SBL-1 mixer and take the IF out to a
center zero meter

through a series pot (meter sensitivity control). You can watch the
needle swing left to right

slowly and correct an oscillator with GPSDO. I usually compare a
rubidium against GPSDO.

Raj, vu2zap

On 21/01/2023 12:47 PM, David J Taylor via groups.io wrote:

- Show quoted text -

David J Taylor 2023/01/22 08:56

On 22/01/2023 06:50, Raj vu2zap wrote:
> David,
>
> I feed two oscillators into a SBL-1 mixer and take the IF out to a center zero
> meter
>
> through a series pot (meter sensitivity control). You can watch the needle
> swing left to right
>
> slowly and correct an oscillator with GPSDO. I usually compare a rubidium
> against GPSDO.
>
> Raj, vu2zap

Raj,

I used a TinySA Ultra with the TinyPFA software:
https://www.tinydevices.org/wiki/pmwiki.php?n=TinyPFA.Homepage

One example here from Owen Duffy:
https://owenduffy.net/blog/?p=27681

Your method is an excellent one. What I've tended to do is to use harmonics
(they are mostly square wave outputs) so trimming TCXO against as high a
frequency as I can manage (odd harmonics are usually easily detectable). The
steps in the typical programmable divider used in these small boxes are easy to
spot - you have to go for the nearest!

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv

Nels Nelsen 2023/01/22 13:21

David, Hi,
Thank you for the information, I was wondering about a way to do that. I
want to compare some 800 MHz trunked transmitters that are GPS referenced
for stability and accuracy and some FM transmitters. This will be a lot
easier than my idea. So much better.

Thank you
Nels Nelsen
NE7LS

On Sat, Jan 21, 2023, 11:16 PM Raj vu2zap <rajendrakumargg@gmail.com> wrote:

- Show quoted text -

Raj vu2zap 2023/01/23 12:08

Here is my KISS mode comparator!

Mixer-s.jpg

W4JDY 2023/02/04 09:53

As a DoD engineer for major weapon systems, this vein is ridiculous, as I have bigger things to worry about other than desktop publishing.

Human errors – Earth to Mr. Spock over !!!

Robert Cartier 2023/02/06 09:45

This is absolute nuts.. Is it me or do people find it imperative to critique all emails for accuracy

I made a mistake during email construction.. You wonder why the hobby is in trouble
everyone is trolling and quick to find fault about an abbreviation but did anyone answer my question about the hardware

I think there was one.

SMH

Robert Cartier
kd1jg@icloud.com

Bob Groh wa2cky 2023/02/07 07:05

Bob, I totally agree with you. I groaned when I saw some of the responses. Goodness sake, what a bunch of ......well, you know what I mean.

Regarding solutions to your 5 MHz problem, I think the one what makes the most sense to me is that you are getting a strong interfering signal. The front end of the NanoVNA is wide open and it wouldn't take much (i.e. a very strong broadcast station) to muck things up.

73
Bob Groh, WA2CKY

Robert Cartier 2023/02/09 05:16

i contacted the vendor and they informed me that there is issues with their unit below 5 Mhz

you see i am not crazy

=====================
*this is their reply*

Hi Robert,

when the freq is under 4mhz, the coupling degree of our saa2n will perform less satisfactarily, which is the original settting for it so we do not recommend test it on low freq, you could use nanovna for better accuracy in low freq.

Helena.
AURSINC

nanov2support 2023/02/09 06:50

Hi, as this hardware is a clone (we have never produced this version), it is not guaranteed to meet any of the NanoRFE specifications, because they do not have the QC and test software we developed, and all clones are missing the factory calibration data that is required to get good results at the lower and upper end of component limits. Please see https://nanorfe.com/nanovna-v2.html for official stores if you are looking for original hardware that is tested to meet specs.

Beware of cheap underperforming clones

NanoVNA SAA-N2 giving incorrect values below 5 mhz