Topics

Low Cost VNA


John Quarmby
 

Members of the group might be interested in this low cost VNA that covers 50kHz-3GHz:

https://www.aliexpress.com/item/1005001267696890.html

Sam G4DDK has measured his compared to an HP VNA and cal kit, and thinks its good value.

It will actually go up to about 4GHz but with unknown accuracy.

Its in a rugged metal case and with N connectors so good for external work on antennas.

Several of my locals now have this. Delivery about 3-4 weeks from order, and it appears to creep into the UK without any VAT to pay (so far).

73

John G3XDY


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geoffrey pike
 

I have the sma SAA-2 and it is worryingly good, almost regret buying the 1.3 GHz VNA but these new things weren't 
available then, the software for the PC does a fine job but the recent Windows update caused havoc with it,
cheers
Geoff
GI0GDP

On Monday, 28 September 2020, 18:51:14 BST, John Quarmby via groups.io <g3xdy@...> wrote:


Members of the group might be interested in this low cost VNA that
covers 50kHz-3GHz:


Sam G4DDK has measured his compared to an HP VNA and cal kit, and thinks
its good value.

It will actually go up to about 4GHz but with unknown accuracy.

Its in a rugged metal case and with N connectors so good for external
work on antennas.

Several of my locals now have this. Delivery about 3-4 weeks from order,
and it appears to creep into the UK without any VAT to pay (so far).

73

John G3XDY


--
This email has been checked for viruses by Avast antivirus software.







Colin Ranson
 

Hi John,

 

Whats the postage please ?    I see them on fleabay for about £73 inclusive from china. I have a PS100 which does 137 MHz to 2.7GHz which has proved useful after calibration.... but the 50KHz up bit looks even better.

 

Regards,

 

Colin de G8LBS.....almost free of the decorating shackles.... I’ve missed some good conditions I hear ?

 

Sent from Mail for Windows 10

 

From: John Quarmby via groups.io
Sent: 28 September 2020 18:51
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] Low Cost VNA

 

Members of the group might be interested in this low cost VNA that
covers 50kHz-3GHz:

https://www.aliexpress.com/item/1005001267696890.html

Sam G4DDK has measured his compared to an HP VNA and cal kit, and thinks
its good value.

It will actually go up to about 4GHz but with unknown accuracy.

Its in a rugged metal case and with N connectors so good for external
work on antennas.

Several of my locals now have this. Delivery about 3-4 weeks from order,
and it appears to creep into the UK without any VAT to pay (so far).

73

John G3XDY


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This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus





 


Andy
 

I had a look earlier today and cost was about £56 with about £13 p&p to the UK

73
Andy



From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of Colin Ranson <g8lbs@...>
Sent: Monday, September 28, 2020 11:41 AM
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] Low Cost VNA
 

Hi John,

 

Whats the postage please ?    I see them on fleabay for about £73 inclusive from china. I have a PS100 which does 137 MHz to 2.7GHz which has proved useful after calibration.... but the 50KHz up bit looks even better.

 

Regards,

 

Colin de G8LBS.....almost free of the decorating shackles.... I’ve missed some good conditions I hear ?

 

Sent from Mail for Windows 10

 

From: John Quarmby via groups.io
Sent: 28 September 2020 18:51
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] Low Cost VNA

 

Members of the group might be interested in this low cost VNA that
covers 50kHz-3GHz:

https://www.aliexpress.com/item/1005001267696890.html

Sam G4DDK has measured his compared to an HP VNA and cal kit, and thinks
its good value.

It will actually go up to about 4GHz but with unknown accuracy.

Its in a rugged metal case and with N connectors so good for external
work on antennas.

Several of my locals now have this. Delivery about 3-4 weeks from order,
and it appears to creep into the UK without any VAT to pay (so far).

73

John G3XDY


--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus





 


g3zqu
 

Has anybody successfully filled in the shipping info form on this website? Only allowing 4 numbers in the phone details and not allowing entry of your town!
Martin G3ZQU


Alan Melia
 


Hi Martin I don't remember having that problem with my Order is it was the Aliexpress site ! I can't find the invoice at the momet but I seem o remember the address was a bit scambled on the label but Royal Snail seemed to make sense of it.
 
Alan
G3NYK
 

----- Original Message -----
Sent: Tuesday, September 29, 2020 4:09 PM
Subject: Re: [UKMicrowaves] Low Cost VNA

Has anybody successfully filled in the shipping info form on this website? Only allowing 4 numbers in the phone details and not allowing entry of your town!
Martin G3ZQU


David Redman
 

Martin
Set country to 'uk' then next box to 'other' then you can type in your town on the next box rather than from the limited list of  cities in the drop down box

Dave
G4IDR 




On Tue, 29 Sep 2020, 16:09 g3zqu via groups.io, <g3zqu=btinternet.com@groups.io> wrote:
Has anybody successfully filled in the shipping info form on this website? Only allowing 4 numbers in the phone details and not allowing entry of your town!
Martin G3ZQU


Tim, VK2XAX
 

Has anyone published a comparison or review between this thing and a real VNA ?

I'd be interested to read that.

A quick search of the net shows people doing things with the NanoVNA but I've not seen a proper comparison of it vs something real.

thanks

Tim

--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA


Lou Blasco
 

Hi Tim,

Owen Duffy has written about it on a number of occasions. He never sits on the fence.


Regards

Lou
VK3ALB


On Wed, Sep 30, 2020 at 2:07 PM Tim, VK2XAX <VK2XAX@...> wrote:
Has anyone published a comparison or review between this thing and a
real VNA ?

I'd be interested to read that.

A quick search of the net shows people doing things with the NanoVNA but
I've not seen a proper comparison of it vs something real.

thanks

Tim

--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA







Paul Entwistle
 

Tim - I bought one of these for setting up POTY antennas - based on the cost it has proved invaluable.

My decision to purchase was, in part, coloured by a very brief comparison by DD1US (below)- may help you decide.

http://www.dd1us.de/Downloads/Brief%20comparison%20of%20NanoVNA%20V2%20with%20a%20professional%20VNA%20HP-8753E.pdf

Paul G8AFC/3B8HE

-----Original Message-----
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Tim, VK2XAX
Sent: 30 September 2020 05:07
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Low Cost VNA

Has anyone published a comparison or review between this thing and a
real VNA ?

I'd be interested to read that.

A quick search of the net shows people doing things with the NanoVNA but
I've not seen a proper comparison of it vs something real.

thanks

Tim

--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA


Tim, VK2XAX
 

Hi Lou,

My googlefu must be off! I didn't find anything from him last time I looked, I should have gone direct to Owen's web site instead of relying on google.

I love reading his stuff, pulls no punches :D

thanks

Tim


On 30/9/20 5:26 pm, Lou Blasco wrote:
Hi Tim,

Owen Duffy has written about it on a number of occasions. He never sits on the fence.


Regards

Lou
VK3ALB


On Wed, Sep 30, 2020 at 2:07 PM Tim, VK2XAX <VK2XAX@...> wrote:
Has anyone published a comparison or review between this thing and a
real VNA ?

I'd be interested to read that.

A quick search of the net shows people doing things with the NanoVNA but
I've not seen a proper comparison of it vs something real.

thanks

Tim

--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA






-- 
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA


Tim, VK2XAX
 

Hi Paul,

Interesting read, I hope he does a more extensive test

thanks

Tim

On 30/9/20 5:30 pm, Paul Entwistle via groups.io wrote:
Tim - I bought one of these for setting up POTY antennas - based on the cost it has proved invaluable.

My decision to purchase was, in part, coloured by a very brief comparison by DD1US (below)- may help you decide.

http://www.dd1us.de/Downloads/Brief%20comparison%20of%20NanoVNA%20V2%20with%20a%20professional%20VNA%20HP-8753E.pdf

Paul G8AFC/3B8HE

-----Original Message-----
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Tim, VK2XAX
Sent: 30 September 2020 05:07
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Low Cost VNA

Has anyone published a comparison or review between this thing and a
real VNA ?

I'd be interested to read that.

A quick search of the net shows people doing things with the NanoVNA but
I've not seen a proper comparison of it vs something real.

thanks

Tim
--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA


alwyn.seeds1
 

Dear All,

All NanoVNAs are not equal. There seem to be a number of versions from a large number of resellers.

I had one of the original caseless NanoVNAs and found it useful; now have the large screen metal-boxed NanoVNA-F version, which is even more useful.

I bought that from the Deepelec store on Ali Express. Transaction was quick and smooth.

I have done a few comparisons with work VNAs and using professional calibration standards there is little (<1dB, +/-10 deg) difference for return losses up to 25 dB at frequencies up to 900 MHz.

The top range up to 1500 MHz is noisier, but still very useful for eg setting up aerials.

The biggest cause of uncertainty is the calibration standards used, nothing new here!

In summary, superb value for money, but choose your supplier carefully as there are so many look-alikes.

Hope that helps.

Regards,

Alwyn G8DOH




_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


Mark GM4ISM
 

Hi all

I have not done direct comparison tests ( I rarely get my eldery 8754A VNA out) but a few publications have indicated that the results are broadly similar.

I do however us VNAs extensively and know  their limitation and pitfalls in their use.

 The Nano VNAs stack up moderately well overall and on most circumstances are  more than adequate

Here are a few comparisons


Frequency range.. The Nano VNA  has a lower minimum frequency than many older 'affordable' large VNAs  making it great for MF and LF antenna work that are out of range to the big boys

At the upper extent of the nanoVNA type frequency range the dynamic range is significantly reduced. If you are looking at broadcast critical mask professional filters you will not be able to determine the stop-band characteristics.

If you are sweeping your amateur band transverter filters you will see far enough down to  be able to tune them up and know they are working adequately

The lack of dynamic range is no issue for return loss measurements. You will be able to  'measure' return losses that are meaningful  (More on that later)

Provided calibration standards on the unit I purchased (a nanoVNA-F) we surprisingly good. I have access to professional cal kits as i mentioned in a previous post on 18 Aug  and the return loss of the supplied load was 35db over the instruments 1500MHz range

One thing I have not seen mentioned is that when you calibrate a VNA, the directivity of the instrument  becomes equal to the return loss of the calibration load  this limits the accuracy of further measurements   in general you can measure  return loss with reasonable accuracy  at about 15dB below your directivity  ie 35 dB directivity  with mean if the analyser says 20db Ret loss that is pretty close.   This is plenty good enough for  most amateur applications and  even acceptable in many cases in the professional world.  The flip side of this is that if you succeed in achieving an indicated perfect match say  50dB or more tha catual return loss of the measured device become equal to the directivity of the  instrument   / the return loss of you calibrated load.

The Nano VNA is no different in this respect

The number of measurement points is the other limitation of the nanoVNA  over a wide sweep the frequency granularity will be poor. I believe that you can stitch adjacent  captures in some software to increase the effective resolution.  In practice this limited number of points  is not a big problem for most measurements with the exception of TDR (Distance to fault)

The distance resolution of the 'TDR' function and its maximum distance is related to the frequency span and the number of points .   With this limitation the nanoVNA does not compare well to 'proper' VNAs   You can still discern roughly where the fault / discontinuity  may be  but you wont see every joint  and kink in the system.  I am used to the fine resolution but from a practical point of view knowing where to look on simple amateur antenna systems is a very good start

It would in theory be possible to  collect the raw data  of multiple sweeps and do the FFT calculations  externally

The last niggle with the nanao VNA that I have ( and i suspect most) is that it is painfully slow in responding to button pushes.  It is usable but could do with more processing grunt

A positive.. Its extremely portable!

Overall the line up well against the  bigger instrument and at the price means that if you want to learn more about VNAs  and how to use them, or are familiar with them  and want to tune loads of filters and check antennas but  don't want to spend big money, they are  really very good value.

Mark GM4ISM



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https://www.avg.com


geoffrey pike
 

Surely the item originally mentioned has nothing to do with the NanoVNA, the SAA-2 is a different beastie from
what i understand and from the start was a 3GHz device where as the Nano VNA was originally a 900 MHz but now
variants have extended this range.
Geoff
GI0GDP

On Wednesday, 30 September 2020, 09:44:32 BST, Mark GM4ISM via groups.io <gm4ism@...> wrote:


Hi all

I have not done direct comparison tests ( I rarely get my eldery 8754A
VNA out) but a few publications have indicated that the results are
broadly similar.

I do however us VNAs extensively and know  their limitation and pitfalls
in their use.

 The Nano VNAs stack up moderately well overall and on most
circumstances are  more than adequate

Here are a few comparisons


Frequency range.. The Nano VNA  has a lower minimum frequency than many
older 'affordable' large VNAs  making it great for MF and LF antenna
work that are out of range to the big boys

At the upper extent of the nanoVNA type frequency range the dynamic
range is significantly reduced. If you are looking at broadcast critical
mask professional filters you will not be able to determine the
stop-band characteristics.

If you are sweeping your amateur band transverter filters you will see
far enough down to  be able to tune them up and know they are working
adequately

The lack of dynamic range is no issue for return loss measurements. You
will be able to  'measure' return losses that are meaningful  (More on
that later)

Provided calibration standards on the unit I purchased (a nanoVNA-F) we
surprisingly good. I have access to professional cal kits as i mentioned
in a previous post on 18 Aug  and the return loss of the supplied load
was 35db over the instruments 1500MHz range

One thing I have not seen mentioned is that when you calibrate a VNA,
the directivity of the instrument  becomes equal to the return loss of
the calibration load  this limits the accuracy of further measurements  
in general you can measure  return loss with reasonable accuracy  at
about 15dB below your directivity  ie 35 dB directivity  with mean if
the analyser says 20db Ret loss that is pretty close.   This is plenty
good enough for  most amateur applications and  even acceptable in many
cases in the professional world.  The flip side of this is that if you
succeed in achieving an indicated perfect match say  50dB or more tha
catual return loss of the measured device become equal to the
directivity of the  instrument   / the return loss of you calibrated load.

The Nano VNA is no different in this respect

The number of measurement points is the other limitation of the nanoVNA 
over a wide sweep the frequency granularity will be poor. I believe that
you can stitch adjacent  captures in some software to increase the
effective resolution.  In practice this limited number of points  is not
a big problem for most measurements with the exception of TDR (Distance
to fault)

The distance resolution of the 'TDR' function and its maximum distance
is related to the frequency span and the number of points .   With this
limitation the nanoVNA does not compare well to 'proper' VNAs   You can
still discern roughly where the fault / discontinuity  may be  but you
wont see every joint  and kink in the system.  I am used to the fine
resolution but from a practical point of view knowing where to look on
simple amateur antenna systems is a very good start

It would in theory be possible to  collect the raw data  of multiple
sweeps and do the FFT calculations  externally

The last niggle with the nanao VNA that I have ( and i suspect most) is
that it is painfully slow in responding to button pushes.  It is usable
but could do with more processing grunt

A positive.. Its extremely portable!

Overall the line up well against the  bigger instrument and at the price
means that if you want to learn more about VNAs  and how to use them, or
are familiar with them  and want to tune loads of filters and check
antennas but  don't want to spend big money, they are  really very good
value.

Mark GM4ISM



--
This email has been checked for viruses by AVG.
https://www.avg.com







Mark GM4ISM
 

Hi Geoff

You are right. A number of  sellers are  listing the SAA-2 as NanoVNA  so I hadn't spotted the differences in the hardware. I assumed it was another extension sampling trick.

The 3GHz upper range is really useful, with the caveat that the cal load is  good that high up.

Principal advantages

Increase to 201 sample points  instead of 101, TDR functionality will improve a bit.  A professional modern VNA may have 1601 points or more

Specified dynamic range is improved at the higher frequency end but still wont match a  'big' VNA 

A lot of the notes below are based on the device having the  published specs, which for the version I have,  seem to be met. 

The SAA-2 spec is   better than the classic NanoVNA but the limitations still  hold.  (but weren't  much of an issue in the first place)

It  should be noted that the open frame versions (ie no metal case shielding) do not always reach their full potential for dynamic range in a  normal RF environment.

You get what you pay for.  A shielded version of any of these is likely to perform better than an unshielded version.

With  the improvements in technology  moving so fast  I would expect  small cheap  devices to really rival big VNAs  in the near future for most tasks.

Mark GM4ISM


On 30/09/2020 10:24, geoffrey pike via groups.io wrote:
Surely the item originally mentioned has nothing to do with the NanoVNA, the SAA-2 is a different beastie from
what i understand and from the start was a 3GHz device where as the Nano VNA was originally a 900 MHz but now
variants have extended this range.
Geoff
GI0GDP

On Wednesday, 30 September 2020, 09:44:32 BST, Mark GM4ISM via groups.io <gm4ism@...> wrote:


Hi all

I have not done direct comparison tests ( I rarely get my eldery 8754A
VNA out) but a few publications have indicated that the results are
broadly similar.

I do however us VNAs extensively and know  their limitation and pitfalls
in their use.

 The Nano VNAs stack up moderately well overall and on most
circumstances are  more than adequate

Here are a few comparisons


Frequency range.. The Nano VNA  has a lower minimum frequency than many
older 'affordable' large VNAs  making it great for MF and LF antenna
work that are out of range to the big boys

At the upper extent of the nanoVNA type frequency range the dynamic
range is significantly reduced. If you are looking at broadcast critical
mask professional filters you will not be able to determine the
stop-band characteristics.

If you are sweeping your amateur band transverter filters you will see
far enough down to  be able to tune them up and know they are working
adequately

The lack of dynamic range is no issue for return loss measurements. You
will be able to  'measure' return losses that are meaningful  (More on
that later)

Provided calibration standards on the unit I purchased (a nanoVNA-F) we
surprisingly good. I have access to professional cal kits as i mentioned
in a previous post on 18 Aug  and the return loss of the supplied load
was 35db over the instruments 1500MHz range

One thing I have not seen mentioned is that when you calibrate a VNA,
the directivity of the instrument  becomes equal to the return loss of
the calibration load  this limits the accuracy of further measurements  
in general you can measure  return loss with reasonable accuracy  at
about 15dB below your directivity  ie 35 dB directivity  with mean if
the analyser says 20db Ret loss that is pretty close.   This is plenty
good enough for  most amateur applications and  even acceptable in many
cases in the professional world.  The flip side of this is that if you
succeed in achieving an indicated perfect match say  50dB or more tha
catual return loss of the measured device become equal to the
directivity of the  instrument   / the return loss of you calibrated load.

The Nano VNA is no different in this respect

The number of measurement points is the other limitation of the nanoVNA 
over a wide sweep the frequency granularity will be poor. I believe that
you can stitch adjacent  captures in some software to increase the
effective resolution.  In practice this limited number of points  is not
a big problem for most measurements with the exception of TDR (Distance
to fault)

The distance resolution of the 'TDR' function and its maximum distance
is related to the frequency span and the number of points .   With this
limitation the nanoVNA does not compare well to 'proper' VNAs   You can
still discern roughly where the fault / discontinuity  may be  but you
wont see every joint  and kink in the system.  I am used to the fine
resolution but from a practical point of view knowing where to look on
simple amateur antenna systems is a very good start

It would in theory be possible to  collect the raw data  of multiple
sweeps and do the FFT calculations  externally

The last niggle with the nanao VNA that I have ( and i suspect most) is
that it is painfully slow in responding to button pushes.  It is usable
but could do with more processing grunt

A positive.. Its extremely portable!

Overall the line up well against the  bigger instrument and at the price
means that if you want to learn more about VNAs  and how to use them, or
are familiar with them  and want to tune loads of filters and check
antennas but  don't want to spend big money, they are  really very good
value.

Mark GM4ISM



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https://www.avg.com







Virus-free. www.avg.com


John Quarmby
 

Just to add to the resolution topic - when connected to a PC via the USB interface for bench measurements the frequency resolution on the PC app increases to 1028 points, useful for plotting sharp notches for example. Measuring my 23cm harmonic notch filter for through loss and return loss gives almost identical results on the SAA-2N as on an Agilent 6GHz scalar analyser under these conditions.

73

John G3XDY

On 30/09/2020 11:33, Mark GM4ISM via groups.io wrote:

Hi Geoff

You are right. A number of  sellers are  listing the SAA-2 as NanoVNA  so I hadn't spotted the differences in the hardware. I assumed it was another extension sampling trick.

The 3GHz upper range is really useful, with the caveat that the cal load is  good that high up.

Principal advantages

Increase to 201 sample points  instead of 101, TDR functionality will improve a bit.  A professional modern VNA may have 1601 points or more

Specified dynamic range is improved at the higher frequency end but still wont match a  'big' VNA 

A lot of the notes below are based on the device having the  published specs, which for the version I have,  seem to be met. 

The SAA-2 spec is   better than the classic NanoVNA but the limitations still  hold.  (but weren't  much of an issue in the first place)

It  should be noted that the open frame versions (ie no metal case shielding) do not always reach their full potential for dynamic range in a  normal RF environment.

You get what you pay for.  A shielded version of any of these is likely to perform better than an unshielded version.

With  the improvements in technology  moving so fast  I would expect  small cheap  devices to really rival big VNAs  in the near future for most tasks.

Mark GM4ISM


On 30/09/2020 10:24, geoffrey pike via groups.io wrote:
Surely the item originally mentioned has nothing to do with the NanoVNA, the SAA-2 is a different beastie from
what i understand and from the start was a 3GHz device where as the Nano VNA was originally a 900 MHz but now
variants have extended this range.
Geoff
GI0GDP

On Wednesday, 30 September 2020, 09:44:32 BST, Mark GM4ISM via groups.io <gm4ism@...> wrote:


Hi all

I have not done direct comparison tests ( I rarely get my eldery 8754A
VNA out) but a few publications have indicated that the results are
broadly similar.

I do however us VNAs extensively and know  their limitation and pitfalls
in their use.

 The Nano VNAs stack up moderately well overall and on most
circumstances are  more than adequate

Here are a few comparisons


Frequency range.. The Nano VNA  has a lower minimum frequency than many
older 'affordable' large VNAs  making it great for MF and LF antenna
work that are out of range to the big boys

At the upper extent of the nanoVNA type frequency range the dynamic
range is significantly reduced. If you are looking at broadcast critical
mask professional filters you will not be able to determine the
stop-band characteristics.

If you are sweeping your amateur band transverter filters you will see
far enough down to  be able to tune them up and know they are working
adequately

The lack of dynamic range is no issue for return loss measurements. You
will be able to  'measure' return losses that are meaningful  (More on
that later)

Provided calibration standards on the unit I purchased (a nanoVNA-F) we
surprisingly good. I have access to professional cal kits as i mentioned
in a previous post on 18 Aug  and the return loss of the supplied load
was 35db over the instruments 1500MHz range

One thing I have not seen mentioned is that when you calibrate a VNA,
the directivity of the instrument  becomes equal to the return loss of
the calibration load  this limits the accuracy of further measurements  
in general you can measure  return loss with reasonable accuracy  at
about 15dB below your directivity  ie 35 dB directivity  with mean if
the analyser says 20db Ret loss that is pretty close.   This is plenty
good enough for  most amateur applications and  even acceptable in many
cases in the professional world.  The flip side of this is that if you
succeed in achieving an indicated perfect match say  50dB or more tha
catual return loss of the measured device become equal to the
directivity of the  instrument   / the return loss of you calibrated load.

The Nano VNA is no different in this respect

The number of measurement points is the other limitation of the nanoVNA 
over a wide sweep the frequency granularity will be poor. I believe that
you can stitch adjacent  captures in some software to increase the
effective resolution.  In practice this limited number of points  is not
a big problem for most measurements with the exception of TDR (Distance
to fault)

The distance resolution of the 'TDR' function and its maximum distance
is related to the frequency span and the number of points .   With this
limitation the nanoVNA does not compare well to 'proper' VNAs   You can
still discern roughly where the fault / discontinuity  may be  but you
wont see every joint  and kink in the system.  I am used to the fine
resolution but from a practical point of view knowing where to look on
simple amateur antenna systems is a very good start

It would in theory be possible to  collect the raw data  of multiple
sweeps and do the FFT calculations  externally

The last niggle with the nanao VNA that I have ( and i suspect most) is
that it is painfully slow in responding to button pushes.  It is usable
but could do with more processing grunt

A positive.. Its extremely portable!

Overall the line up well against the  bigger instrument and at the price
means that if you want to learn more about VNAs  and how to use them, or
are familiar with them  and want to tune loads of filters and check
antennas but  don't want to spend big money, they are  really very good
value.

Mark GM4ISM



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This email has been checked for viruses by AVG.
https://www.avg.com







Virus-free. www.avg.com


dbztuzujdhgtrjzthxh
 

The NanoVNA (plus its clones and derivatives) are best thought of as the Gen.1 machine.
The SAA2 (otherwise known as NanoVNA V2) is the Gen.2.

Of the Gen.2 family, there is the V2.2 (already discontinued) replaced by the V2 Plus (V2.3) and the soon to be release V2 Plus4 (V2.4)

The V2.4 is claimed to go to 4.4GHz


Chris Bartram G4DGU
 

Hello John,

How long does a 1024 point sweep take under PC control?

73

Chris G4DGU

On 30/09/2020 14:35, John Quarmby via groups.io wrote:

Just to add to the resolution topic - when connected to a PC via the USB interface for bench measurements the frequency resolution on the PC app increases to 1028 points, useful for plotting sharp notches for example. Measuring my 23cm harmonic notch filter for through loss and return loss gives almost identical results on the SAA-2N as on an Agilent 6GHz scalar analyser under these conditions.


John Quarmby
 

Hi Chris

A quick test shows it was about 20 seconds for a 1024 point sweep from 1GHz to 4GHz which is what I had it last set up for.

73

John G3XDY

On 30/09/2020 14:12, Chris Bartram G4DGU wrote:
Hello John,

How long does a 1024 point sweep take under PC control?

73

Chris G4DGU


On 30/09/2020 14:35, John Quarmby via groups.io wrote:

Just to add to the resolution topic - when connected to a PC via the USB interface for bench measurements the frequency resolution on the PC app increases to 1028 points, useful for plotting sharp notches for example. Measuring my 23cm harmonic notch filter for through loss and return loss gives almost identical results on the SAA-2N as on an Agilent 6GHz scalar analyser under these conditions.


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