NanoVNA #calibration


Radu Bogdan Dicher
 

Hi all,
Newbee here, so please excuse redundancy of questions, unawareness of previous topics, etc. Did my best to research before posting, but find myself at a dead end.

I'm trying to use my newly acquired NanoVNA to sort FM IF filters. I built a little contraption to socket filters and allow for measurement etc. May post pictures later, depending on where the conversation will go.

As I'm pretty consistently getting likely incorrect readings - namely not symmetric around 10.7MHz (or wherever their center is) - the issue of re-calibrating the device was brought about.

A couple of issues with this:
1. I understand there's hardware I got in the box with the device for doing this, but there's no indication of which component from the box is what. I may be missing something starring me in the face, but it's been a really frustrating experience to not even see some basic markings on the parts, get some guidelines with the kit, etc. This was bought from R&L Electronics in the US.
2. I think I have the PDF of what seems to be the document going through the calibration procedure - it's in the files here, and is v1.1 - is this it?

Thank you much in advance!
Radu.


Paul W8SBH
 

The test attachments with my model H are easy to interpret. The 50ohm is
"silver" in color. The open circuit is an empty cavity. The short has a
center pin. You can even leave the fitting off for an "open".

min telfon nayad sh'li

On Tue, May 5, 2020, 5:48 PM Radu Bogdan Dicher <vondicher@gmail.com> wrote:

Hi all,
Newbee here, so please excuse redundancy of questions, unawareness of
previous topics, etc. Did my best to research before posting, but find
myself at a dead end.

I'm trying to use my newly acquired NanoVNA to sort FM IF filters. I built
a little contraption to socket filters and allow for measurement etc. May
post pictures later, depending on where the conversation will go.

As I'm pretty consistently getting likely incorrect readings - namely not
symmetric around 10.7MHz (or wherever their center is) - the issue of
re-calibrating the device was brought about.

A couple of issues with this:
1. I understand there's hardware I got in the box with the device for
doing this, but there's no indication of which component from the box is
what. I may be missing something starring me in the face, but it's been a
really frustrating experience to not even see some basic markings on the
parts, get some guidelines with the kit, etc. This was bought from R&L
Electronics in the US.
2. I think I have the PDF of what seems to be the document going through
the calibration procedure - it's in the files here, and is v1.1 - is this
it?

Thank you much in advance!
Radu.




Al Schwartz
 

Not sure what you may be missing. Need three or four items to calibrate.
Open can be connector with nothing attached or you can use the gold SMA cap
with no center pin. Short is gold SMA cap with center pin. Load/termination
is slightly larger gold and silver cap. For thru measurement you need an
SMA M-M cable. Should have been 2x SMA cable and SMA F-F included with
unit, else how can you calibrate? Do you have these?


Jim Allyn - N7JA
 

Once you get the NanoVNA calibrated properly, you will want to terminate the filters in the impedance they were designed for. If you're talking 10.7 MHz ceramic filters for FM broadcast receivers, most of them used to be 330 ohms if I remember correctly. You could use a minimum loss impedance matching attenuator, or an LC matching network.


Dick
 

Why would you need to connect anything if it's an Open ?

73, Dick, W1KSZ
________________________________
From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of Al Schwartz <whdpc113@gmail.com>
Sent: Tuesday, May 5, 2020 4:40 PM
To: nanovna-users@groups.io <nanovna-users@groups.io>
Subject: Re: [nanovna-users] NanoVNA

Not sure what you may be missing. Need three or four items to calibrate.
Open can be connector with nothing attached or you can use the gold SMA cap
with no center pin. Short is gold SMA cap with center pin. Load/termination
is slightly larger gold and silver cap. For thru measurement you need an
SMA M-M cable. Should have been 2x SMA cable and SMA F-F included with
unit, else how can you calibrate? Do you have these?


SgtJUSMC
 

Not sure if you've seen this, but there are manuals available for down load
at this site.
https://drive.google.com/drive/folders/1-JViWLBOIzaHTdwdONX2RP8S4EgWxoND

On Tue, May 5, 2020 at 5:48 PM Radu Bogdan Dicher <vondicher@gmail.com>
wrote:

Hi all,
Newbee here, so please excuse redundancy of questions, unawareness of
previous topics, etc. Did my best to research before posting, but find
myself at a dead end.

I'm trying to use my newly acquired NanoVNA to sort FM IF filters. I built
a little contraption to socket filters and allow for measurement etc. May
post pictures later, depending on where the conversation will go.

As I'm pretty consistently getting likely incorrect readings - namely not
symmetric around 10.7MHz (or wherever their center is) - the issue of
re-calibrating the device was brought about.

A couple of issues with this:
1. I understand there's hardware I got in the box with the device for
doing this, but there's no indication of which component from the box is
what. I may be missing something starring me in the face, but it's been a
really frustrating experience to not even see some basic markings on the
parts, get some guidelines with the kit, etc. This was bought from R&L
Electronics in the US.
2. I think I have the PDF of what seems to be the document going through
the calibration procedure - it's in the files here, and is v1.1 - is this
it?

Thank you much in advance!
Radu.



--
Semper Fi,

Viva Christo Rey!

"A new type of superstition has got hold of peoples minds, the worship of
the state. People demand the exercise of the methods of coercion and
compulsion, of violence and threat. Woe to anybody who does not bend his
knee to the fashionable idols!" - Ludwig von Mises


John


Jim Allyn - N7JA
 

If the filters are not properly impedance matched, they will not be symmetrical. In fact, the passband may be horribly distorted compared to what you expect. Further, the group delay of the filter will be screwy, which is important to those going for minimum distortion in their FM receivers.


Radu Bogdan Dicher
 

Thank you all.

Firstly - on the attachments. Paul: I guess by elimination works great! ;)
In fact, makes complete sense and thank you.

Secondly - on the filters. Jim: yes, I am terminating the measuring rig
properly by impedance matching (closest possible to 330ohm to filters and
50ohm to the NanoVNA). Even after eliminating unnecessary
complications (50ohm BNC cables, SMA adapters, etc.), the filters response
is still screwy (though much improved), and this is across multiple
filters. I assume next step on this pursuit is to recalibrate. I assume
this is probably about as good as factory calibration, so there's not much
to loose there.

Thirdly - on the manuals/files: Thank you for that repository, I wasn't
aware of it!

Radu.

On Tue, May 5, 2020 at 6:37 PM Jim Allyn - N7JA <jim@allynelectronics.com>
wrote:

If the filters are not properly impedance matched, they will not be
symmetrical. In fact, the passband may be horribly distorted compared to
what you expect. Further, the group delay of the filter will be screwy,
which is important to those going for minimum distortion in their FM
receivers.




Radu Bogdan Dicher
 

Thank you both, makes complete sense.
Radu.

On Tue, May 5, 2020 at 6:13 PM Dick <w1ksz@outlook.com> wrote:

Why would you need to connect anything if it's an Open ?

73, Dick, W1KSZ
________________________________
From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of Al
Schwartz <whdpc113@gmail.com>
Sent: Tuesday, May 5, 2020 4:40 PM
To: nanovna-users@groups.io <nanovna-users@groups.io>
Subject: Re: [nanovna-users] NanoVNA

Not sure what you may be missing. Need three or four items to calibrate.
Open can be connector with nothing attached or you can use the gold SMA cap
with no center pin. Short is gold SMA cap with center pin. Load/termination
is slightly larger gold and silver cap. For thru measurement you need an
SMA M-M cable. Should have been 2x SMA cable and SMA F-F included with
unit, else how can you calibrate? Do you have these?







EB4APL
 

The good calibration kits establishes a reference plane for the phase, so the Open accessory is not of zero length but it has the same electrical length as the Sort and the Load.  The reference plane then is well defined and  you measure from this plane. Expensive cal kits also includes the real parameters of each kit component, as they are not perfect but can be measured so the imperfections are taken in account in the VNA calibration.

If you are interested in HF only, all these subtleties are superfluous, a few millimeters don't make any difference at the frequencies involved.

73,

Ignacio  EB4APL

El 06/05/2020 a las 3:13, Dick escribió:
Why would you need to connect anything if it's an Open ?

73, Dick, W1KSZ
________________________________
From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of Al Schwartz <whdpc113@gmail.com>
Sent: Tuesday, May 5, 2020 4:40 PM
To: nanovna-users@groups.io <nanovna-users@groups.io>
Subject: Re: [nanovna-users] NanoVNA

Not sure what you may be missing. Need three or four items to calibrate.
Open can be connector with nothing attached or you can use the gold SMA cap
with no center pin. Short is gold SMA cap with center pin. Load/termination
is slightly larger gold and silver cap. For thru measurement you need an
SMA M-M cable. Should have been 2x SMA cable and SMA F-F included with
unit, else how can you calibrate? Do you have these?
--
El software de antivirus Avast ha analizado este correo electrónico en busca de virus.
https://www.avast.com/antivirus


Bill Cromwell
 

Hi Ignacio,

Thank you for validating my perception that those calibration bits are not nearly as critical for HF as they are V/UHF. There have been hints about that elsewhere and that was my own perception. I just received my new H4 with a 4 inch screen and the tracking utility says I will get a boxful of new adapters and cables today. All of my interest is on 160 through about 17 meters. Mine seems to work fine:)

73,

Bill KU8H

On 5/6/20 8:18 AM, EB4APL wrote:
The good calibration kits establishes a reference plane for the phase, so the Open accessory is not of zero length but it has the same electrical length as the Sort and the Load.  The reference plane then is well defined and  you measure from this plane. Expensive cal kits also includes the real parameters of each kit component, as they are not perfect but can be measured so the imperfections are taken in account in the VNA calibration.
If you are interested in HF only, all these subtleties are superfluous, a few millimeters don't make any difference at the frequencies involved.
73,
Ignacio  EB4APL
El 06/05/2020 a las 3:13, Dick escribió:
Why would you need to connect anything if it's an Open ?

73, Dick, W1KSZ
________________________________
From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of Al Schwartz <whdpc113@gmail.com>
Sent: Tuesday, May 5, 2020 4:40 PM
To: nanovna-users@groups.io <nanovna-users@groups.io>
Subject: Re: [nanovna-users] NanoVNA

Not sure what you may be missing. Need three or four items to calibrate.
Open can be connector with nothing attached or you can use the gold SMA cap
with no center pin. Short is gold SMA cap with center pin. Load/termination
is slightly larger gold and silver cap. For thru measurement you need an
SMA M-M cable. Should have been 2x SMA cable and SMA F-F included with
unit, else how can you calibrate? Do you have these?
--
bark less - wag more


Radu Bogdan Dicher
 

I'm at the start of the calibration procedure, and I've connected both
cables on CH0 and CH1, while using the pass-through attachment ("F-F SMA"
in the v1.1 guidelines, in my interpretation) on the other end of the SMA
cable coming from CH0.

The menu steps are clear until step 4, which calls for a "4. SINGLE." I'm
not sure what this is. I don't see it anywhere following/around TRACE 0
(which is there). I wonder if this is due to recent changes in the menu
structure. Or maybe I am just missing something...

Thank you all for your help.
Radu.

On Tue, May 5, 2020 at 7:14 PM Radu Bogdan Dicher via groups.io <vondicher=
gmail.com@groups.io> wrote:

Thank you all.

Firstly - on the attachments. Paul: I guess by elimination works great! ;)
In fact, makes complete sense and thank you.

Secondly - on the filters. Jim: yes, I am terminating the measuring rig
properly by impedance matching (closest possible to 330ohm to filters and
50ohm to the NanoVNA). Even after eliminating unnecessary
complications (50ohm BNC cables, SMA adapters, etc.), the filters response
is still screwy (though much improved), and this is across multiple
filters. I assume next step on this pursuit is to recalibrate. I assume
this is probably about as good as factory calibration, so there's not much
to loose there.

Thirdly - on the manuals/files: Thank you for that repository, I wasn't
aware of it!

Radu.

On Tue, May 5, 2020 at 6:37 PM Jim Allyn - N7JA <jim@allynelectronics.com>
wrote:

If the filters are not properly impedance matched, they will not be
symmetrical. In fact, the passband may be horribly distorted compared to
what you expect. Further, the group delay of the filter will be screwy,
which is important to those going for minimum distortion in their FM
receivers.






Radu Bogdan Dicher
 

I think I figured it, a bit trial and error and such. The idea seems to be
to turn off two traces out of four and make sure the two left follow
certain inputs (LOGMAG for each CH). Past this step, it's a bit weird how
the calibration menu steps one ahead on you, making it a bit confusing as
to whether it completed the previous step or not. But it seems the traces
settle in a way that tells me the device read "itself" and calibrated
accordingly.

I'm repeating the procedure, as my 10.7MHz filters plots still lean lower
on the left side. This is across multiple filters, can't be due to them,
still think it's the device.

On Wed, May 6, 2020 at 7:41 PM Radu Bogdan Dicher via groups.io <vondicher=
gmail.com@groups.io> wrote:

I'm at the start of the calibration procedure, and I've connected both
cables on CH0 and CH1, while using the pass-through attachment ("F-F SMA"
in the v1.1 guidelines, in my interpretation) on the other end of the SMA
cable coming from CH0.

The menu steps are clear until step 4, which calls for a "4. SINGLE." I'm
not sure what this is. I don't see it anywhere following/around TRACE 0
(which is there). I wonder if this is due to recent changes in the menu
structure. Or maybe I am just missing something...

Thank you all for your help.
Radu.

On Tue, May 5, 2020 at 7:14 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

Thank you all.

Firstly - on the attachments. Paul: I guess by elimination works great!
;)
In fact, makes complete sense and thank you.

Secondly - on the filters. Jim: yes, I am terminating the measuring rig
properly by impedance matching (closest possible to 330ohm to filters and
50ohm to the NanoVNA). Even after eliminating unnecessary
complications (50ohm BNC cables, SMA adapters, etc.), the filters
response
is still screwy (though much improved), and this is across multiple
filters. I assume next step on this pursuit is to recalibrate. I assume
this is probably about as good as factory calibration, so there's not
much
to loose there.

Thirdly - on the manuals/files: Thank you for that repository, I wasn't
aware of it!

Radu.

On Tue, May 5, 2020 at 6:37 PM Jim Allyn - N7JA <
jim@allynelectronics.com>
wrote:

If the filters are not properly impedance matched, they will not be
symmetrical. In fact, the passband may be horribly distorted compared
to
what you expect. Further, the group delay of the filter will be
screwy,
which is important to those going for minimum distortion in their FM
receivers.








Radu Bogdan Dicher
 

Hi all,
Having some confidence I've completed calibration on the band of interest
to me (I think I did 10MHz to 11MHz), I am getting the same titled scan of
pretty much any number of filters I threw at this (I enclose a sample). I
am not sure if I need to return this, or request a replacement some other
way.
I contacted the seller (R&L), but it doesn't look like they have stock at
all and they haven't had any in a while.
[image: image.png]
Thank you all for you input.
Radu.

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On Wed, May 6, 2020 at 8:23 PM Radu Bogdan Dicher via groups.io <vondicher=
gmail.com@groups.io> wrote:

I think I figured it, a bit trial and error and such. The idea seems to be
to turn off two traces out of four and make sure the two left follow
certain inputs (LOGMAG for each CH). Past this step, it's a bit weird how
the calibration menu steps one ahead on you, making it a bit confusing as
to whether it completed the previous step or not. But it seems the traces
settle in a way that tells me the device read "itself" and calibrated
accordingly.

I'm repeating the procedure, as my 10.7MHz filters plots still lean lower
on the left side. This is across multiple filters, can't be due to them,
still think it's the device.

On Wed, May 6, 2020 at 7:41 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

I'm at the start of the calibration procedure, and I've connected both
cables on CH0 and CH1, while using the pass-through attachment ("F-F SMA"
in the v1.1 guidelines, in my interpretation) on the other end of the SMA
cable coming from CH0.

The menu steps are clear until step 4, which calls for a "4. SINGLE." I'm
not sure what this is. I don't see it anywhere following/around TRACE 0
(which is there). I wonder if this is due to recent changes in the menu
structure. Or maybe I am just missing something...

Thank you all for your help.
Radu.

On Tue, May 5, 2020 at 7:14 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

Thank you all.

Firstly - on the attachments. Paul: I guess by elimination works great!
;)
In fact, makes complete sense and thank you.

Secondly - on the filters. Jim: yes, I am terminating the measuring rig
properly by impedance matching (closest possible to 330ohm to filters
and
50ohm to the NanoVNA). Even after eliminating unnecessary
complications (50ohm BNC cables, SMA adapters, etc.), the filters
response
is still screwy (though much improved), and this is across multiple
filters. I assume next step on this pursuit is to recalibrate. I assume
this is probably about as good as factory calibration, so there's not
much
to loose there.

Thirdly - on the manuals/files: Thank you for that repository, I wasn't
aware of it!

Radu.

On Tue, May 5, 2020 at 6:37 PM Jim Allyn - N7JA <
jim@allynelectronics.com>
wrote:

If the filters are not properly impedance matched, they will not be
symmetrical. In fact, the passband may be horribly distorted
compared
to
what you expect. Further, the group delay of the filter will be
screwy,
which is important to those going for minimum distortion in their FM
receivers.









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Radu Bogdan Dicher
 

Just to document this a bit better - I placed my calibration data on "c1,"
which I'm recalling (and I see on the left side of the screen, on top)
before running measurements. I calibrated for a CENTER of 10.7MHz, and a
SPAN of 1.4MHz. This was done with the cables in place, including the patch
extension (per guidelines), but my little kit that allows me to socket the
filters was not connected during calibration (I came to wonder if I should
do that).

To continue establishing the baseline of my setup, the kit has proper
termination for the filters (~330ohm) and cables (~50ohm), and also a 10pF
cap on the filters output (per Murata datasheet).


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On Sat, May 23, 2020 at 3:29 PM Radu Bogdan Dicher via groups.io <vondicher=
gmail.com@groups.io> wrote:

Hi all,
Having some confidence I've completed calibration on the band of interest
to me (I think I did 10MHz to 11MHz), I am getting the same titled scan of
pretty much any number of filters I threw at this (I enclose a sample). I
am not sure if I need to return this, or request a replacement some other
way.
I contacted the seller (R&L), but it doesn't look like they have stock at
all and they haven't had any in a while.
[image: image.png]
Thank you all for you input.
Radu.

<
http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail
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On Wed, May 6, 2020 at 8:23 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

I think I figured it, a bit trial and error and such. The idea seems to
be
to turn off two traces out of four and make sure the two left follow
certain inputs (LOGMAG for each CH). Past this step, it's a bit weird how
the calibration menu steps one ahead on you, making it a bit confusing as
to whether it completed the previous step or not. But it seems the traces
settle in a way that tells me the device read "itself" and calibrated
accordingly.

I'm repeating the procedure, as my 10.7MHz filters plots still lean lower
on the left side. This is across multiple filters, can't be due to them,
still think it's the device.

On Wed, May 6, 2020 at 7:41 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

I'm at the start of the calibration procedure, and I've connected both
cables on CH0 and CH1, while using the pass-through attachment ("F-F
SMA"
in the v1.1 guidelines, in my interpretation) on the other end of the
SMA
cable coming from CH0.

The menu steps are clear until step 4, which calls for a "4. SINGLE."
I'm
not sure what this is. I don't see it anywhere following/around TRACE 0
(which is there). I wonder if this is due to recent changes in the menu
structure. Or maybe I am just missing something...

Thank you all for your help.
Radu.

On Tue, May 5, 2020 at 7:14 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

Thank you all.

Firstly - on the attachments. Paul: I guess by elimination works
great!
;)
In fact, makes complete sense and thank you.

Secondly - on the filters. Jim: yes, I am terminating the measuring
rig
properly by impedance matching (closest possible to 330ohm to filters
and
50ohm to the NanoVNA). Even after eliminating unnecessary
complications (50ohm BNC cables, SMA adapters, etc.), the filters
response
is still screwy (though much improved), and this is across multiple
filters. I assume next step on this pursuit is to recalibrate. I
assume
this is probably about as good as factory calibration, so there's not
much
to loose there.

Thirdly - on the manuals/files: Thank you for that repository, I
wasn't
aware of it!

Radu.

On Tue, May 5, 2020 at 6:37 PM Jim Allyn - N7JA <
jim@allynelectronics.com>
wrote:

If the filters are not properly impedance matched, they will not be
symmetrical. In fact, the passband may be horribly distorted
compared
to
what you expect. Further, the group delay of the filter will be
screwy,
which is important to those going for minimum distortion in their
FM
receivers.









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Larry Rothman
 

Please remember that if even if you've saved your new calibration to c1, if you power cycle the Nano, it automatically recalls c0 and you need to manually recall c1 every time you turn the unit ON

On top of that, many Nano units will power cycle when connected to USB power. 


On Sat, 23 May 2020 at 6:56 PM, Radu Bogdan Dicher<vondicher@gmail.com> wrote: Just to document this a bit better - I placed my calibration data on "c1,"
which I'm recalling (and I see on the left side of the screen, on top)
before running measurements. I calibrated for a CENTER of 10.7MHz, and a
SPAN of 1.4MHz. This was done with the cables in place, including the patch
extension (per guidelines), but my little kit that allows me to socket the
filters was not connected during calibration (I came to wonder if I should
do that).

To continue establishing the baseline of my setup, the kit has proper
termination for the filters (~330ohm) and cables (~50ohm), and also a 10pF
cap on the filters output (per Murata datasheet).


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On Sat, May 23, 2020 at 3:29 PM Radu Bogdan Dicher via groups.io <vondicher=
gmail.com@groups.io> wrote:

Hi all,
Having some confidence I've completed calibration on the band of interest
to me (I think I did 10MHz to 11MHz), I am getting the same titled scan of
pretty much any number of filters I threw at this (I enclose a sample). I
am not sure if I need to return this, or request a replacement some other
way.
I contacted the seller (R&L), but it doesn't look like they have stock at
all and they haven't had any in a while.
[image: image.png]
Thank you all for you input.
Radu.

<
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On Wed, May 6, 2020 at 8:23 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

I think I figured it, a bit trial and error and such. The idea seems to
be
to turn off two traces out of four and make sure the two left follow
certain inputs (LOGMAG for each CH). Past this step, it's a bit weird how
the calibration menu steps one ahead on you, making it a bit confusing as
to whether it completed the previous step or not. But it seems the traces
settle in a way that tells me the device read "itself" and calibrated
accordingly.

I'm repeating the procedure, as my 10.7MHz filters plots still lean lower
on the left side. This is across multiple filters, can't be due to them,
still think it's the device.

On Wed, May 6, 2020 at 7:41 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

I'm at the start of the calibration procedure, and I've connected both
cables on CH0 and CH1, while using the pass-through attachment ("F-F
SMA"
in the v1.1 guidelines, in my interpretation) on the other end of the
SMA
cable coming from CH0.

The menu steps are clear until step 4, which calls for a "4. SINGLE."
I'm
not sure what this is. I don't see it anywhere following/around TRACE 0
(which is there). I wonder if this is due to recent changes in the menu
structure. Or maybe I am just missing something...

Thank you all for your help.
Radu.

On Tue, May 5, 2020 at 7:14 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

Thank you all.

Firstly - on the attachments. Paul: I guess by elimination works
great!
;)
In fact, makes complete sense and thank you.

Secondly - on the filters. Jim: yes, I am terminating the measuring
rig
properly by impedance matching (closest possible to 330ohm to filters
and
50ohm to the NanoVNA). Even after eliminating unnecessary
complications (50ohm BNC cables, SMA adapters, etc.), the filters
response
is still screwy (though much improved), and this is across multiple
filters. I assume next step on this pursuit is to recalibrate. I
assume
this is probably about as good as factory calibration, so there's not
much
to loose there.

Thirdly - on the manuals/files: Thank you for that repository, I
wasn't
aware of it!

Radu.

On Tue, May 5, 2020 at 6:37 PM Jim Allyn - N7JA <
jim@allynelectronics.com>
wrote:

If the filters are not properly impedance matched, they will not be
symmetrical.  In fact, the passband may be horribly distorted
compared
to
what you expect.  Further, the group delay of the filter will be
screwy,
which is important to those going for minimum distortion in their
FM
receivers.









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Radu Bogdan Dicher
 

Larry,
Thank you for your input. When I run the scan, I see "c1" on the top/left
side, and I'm always keeping it current.
That said, I just tried in both modes - RECALL 0, and RECALL 1 - and I
can't see a difference in the graph shape. Maybe my calibration hasn't been
successful?... Or, maybe this is a sign the device is defective?
Thank you,
Radu.


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On Sat, May 23, 2020 at 4:04 PM Larry Rothman <nlroth@rogers.com> wrote:

Please remember that if even if you've saved your new calibration to c1,
if you power cycle the Nano, it automatically recalls c0 and you need to
manually recall c1 every time you turn the unit ON

On top of that, many Nano units will power cycle when connected to USB
power.


On Sat, 23 May 2020 at 6:56 PM, Radu Bogdan Dicher<vondicher@gmail.com>
wrote: Just to document this a bit better - I placed my calibration data
on "c1,"
which I'm recalling (and I see on the left side of the screen, on top)
before running measurements. I calibrated for a CENTER of 10.7MHz, and a
SPAN of 1.4MHz. This was done with the cables in place, including the patch
extension (per guidelines), but my little kit that allows me to socket the
filters was not connected during calibration (I came to wonder if I should
do that).

To continue establishing the baseline of my setup, the kit has proper
termination for the filters (~330ohm) and cables (~50ohm), and also a 10pF
cap on the filters output (per Murata datasheet).


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On Sat, May 23, 2020 at 3:29 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

Hi all,
Having some confidence I've completed calibration on the band of interest
to me (I think I did 10MHz to 11MHz), I am getting the same titled scan
of
pretty much any number of filters I threw at this (I enclose a sample). I
am not sure if I need to return this, or request a replacement some other
way.
I contacted the seller (R&L), but it doesn't look like they have stock at
all and they haven't had any in a while.
[image: image.png]
Thank you all for you input.
Radu.

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On Wed, May 6, 2020 at 8:23 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

I think I figured it, a bit trial and error and such. The idea seems to
be
to turn off two traces out of four and make sure the two left follow
certain inputs (LOGMAG for each CH). Past this step, it's a bit weird
how
the calibration menu steps one ahead on you, making it a bit confusing
as
to whether it completed the previous step or not. But it seems the
traces
settle in a way that tells me the device read "itself" and calibrated
accordingly.

I'm repeating the procedure, as my 10.7MHz filters plots still lean
lower
on the left side. This is across multiple filters, can't be due to
them,
still think it's the device.

On Wed, May 6, 2020 at 7:41 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

I'm at the start of the calibration procedure, and I've connected
both
cables on CH0 and CH1, while using the pass-through attachment ("F-F
SMA"
in the v1.1 guidelines, in my interpretation) on the other end of the
SMA
cable coming from CH0.

The menu steps are clear until step 4, which calls for a "4. SINGLE."
I'm
not sure what this is. I don't see it anywhere following/around
TRACE 0
(which is there). I wonder if this is due to recent changes in the
menu
structure. Or maybe I am just missing something...

Thank you all for your help.
Radu.

On Tue, May 5, 2020 at 7:14 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

Thank you all.

Firstly - on the attachments. Paul: I guess by elimination works
great!
;)
In fact, makes complete sense and thank you.

Secondly - on the filters. Jim: yes, I am terminating the measuring
rig
properly by impedance matching (closest possible to 330ohm to
filters
and
50ohm to the NanoVNA). Even after eliminating unnecessary
complications (50ohm BNC cables, SMA adapters, etc.), the filters
response
is still screwy (though much improved), and this is across multiple
filters. I assume next step on this pursuit is to recalibrate. I
assume
this is probably about as good as factory calibration, so there's
not
much
to loose there.

Thirdly - on the manuals/files: Thank you for that repository, I
wasn't
aware of it!

Radu.

On Tue, May 5, 2020 at 6:37 PM Jim Allyn - N7JA <
jim@allynelectronics.com>
wrote:

If the filters are not properly impedance matched, they will not
be
symmetrical. In fact, the passband may be horribly distorted
compared
to
what you expect. Further, the group delay of the filter will be
screwy,
which is important to those going for minimum distortion in their
FM
receivers.









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Larry Rothman
 

Radu,
Please note there is a big difference between upper case C and lower case c as an indication of calibration. 
Refer to the User Guide in the Forum files section. I emphasized this in the section on calibration. 
If you see c0 instead of C0 then the unit is NOT calibrated. (The number can be 0 thru 4)
Remember to always press the Reset menu button before calibration and then Save to one of the memories ( 0 is the power-on recall default memory). 



On Sat, 23 May 2020 at 10:29 PM, Radu Bogdan Dicher<vondicher@gmail.com> wrote: Larry,
Thank you for your input. When I run the scan, I see "c1" on the top/left
side, and I'm always keeping it current.
That said, I just tried in both modes - RECALL 0, and RECALL 1 - and I
can't see a difference in the graph shape. Maybe my calibration hasn't been
successful?... Or, maybe this is a sign the device is defective?
Thank you,
Radu.


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On Sat, May 23, 2020 at 4:04 PM Larry Rothman <nlroth@rogers.com> wrote:

Please remember that if even if you've saved your new calibration to c1,
if you power cycle the Nano, it automatically recalls c0 and you need to
manually recall c1 every time you turn the unit ON

On top of that, many Nano units will power cycle when connected to USB
power.


  On Sat, 23 May 2020 at 6:56 PM, Radu Bogdan Dicher<vondicher@gmail.com>
wrote:  Just to document this a bit better - I placed my calibration data
on "c1,"
which I'm recalling (and I see on the left side of the screen, on top)
before running measurements. I calibrated for a CENTER of 10.7MHz, and a
SPAN of 1.4MHz. This was done with the cables in place, including the patch
extension (per guidelines), but my little kit that allows me to socket the
filters was not connected during calibration (I came to wonder if I should
do that).

To continue establishing the baseline of my setup, the kit has proper
termination for the filters (~330ohm) and cables (~50ohm), and also a 10pF
cap on the filters output (per Murata datasheet).


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On Sat, May 23, 2020 at 3:29 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

Hi all,
Having some confidence I've completed calibration on the band of interest
to me (I think I did 10MHz to 11MHz), I am getting the same titled scan
of
pretty much any number of filters I threw at this (I enclose a sample). I
am not sure if I need to return this, or request a replacement some other
way.
I contacted the seller (R&L), but it doesn't look like they have stock at
all and they haven't had any in a while.
[image: image.png]
Thank you all for you input.
Radu.

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On Wed, May 6, 2020 at 8:23 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

I think I figured it, a bit trial and error and such. The idea seems to
be
to turn off two traces out of four and make sure the two left follow
certain inputs (LOGMAG for each CH). Past this step, it's a bit weird
how
the calibration menu steps one ahead on you, making it a bit confusing
as
to whether it completed the previous step or not. But it seems the
traces
settle in a way that tells me the device read "itself" and calibrated
accordingly.

I'm repeating the procedure, as my 10.7MHz filters plots still lean
lower
on the left side. This is across multiple filters, can't be due to
them,
still think it's the device.

On Wed, May 6, 2020 at 7:41 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

I'm at the start of the calibration procedure, and I've connected
both
cables on CH0 and CH1, while using the pass-through attachment ("F-F
SMA"
in the v1.1 guidelines, in my interpretation) on the other end of the
SMA
cable coming from CH0.

The menu steps are clear until step 4, which calls for a "4. SINGLE."
I'm
not sure what this is. I don't see it anywhere following/around
TRACE 0
(which is there). I wonder if this is due to recent changes in the
menu
structure. Or maybe I am just missing something...

Thank you all for your help.
Radu.

On Tue, May 5, 2020 at 7:14 PM Radu Bogdan Dicher via groups.io
<vondicher=
gmail.com@groups.io> wrote:

Thank you all.

Firstly - on the attachments. Paul: I guess by elimination works
great!
;)
In fact, makes complete sense and thank you.

Secondly - on the filters. Jim: yes, I am terminating the measuring
rig
properly by impedance matching (closest possible to 330ohm to
filters
and
50ohm to the NanoVNA). Even after eliminating unnecessary
complications (50ohm BNC cables, SMA adapters, etc.), the filters
response
is still screwy (though much improved), and this is across multiple
filters. I assume next step on this pursuit is to recalibrate. I
assume
this is probably about as good as factory calibration, so there's
not
much
to loose there.

Thirdly - on the manuals/files: Thank you for that repository, I
wasn't
aware of it!

Radu.

On Tue, May 5, 2020 at 6:37 PM Jim Allyn - N7JA <
jim@allynelectronics.com>
wrote:

If the filters are not properly impedance matched, they will not
be
symmetrical.  In fact, the passband may be horribly distorted
compared
to
what you expect.  Further, the group delay of the filter will be
screwy,
which is important to those going for minimum distortion in their
FM
receivers.









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Dave W6OQ
 

What I see in the plot that you posted is a filter that is about 170 kHz wide at the -3 dB points and centered at 10.715 MHz. This is consistent with a Murata SFELF10M7HA00-B0 that has a spec of 180 +/-40 kHz and a center frequency of 10.7 MHz +/-30 kHz. The fact that all the filters exhibit the same response wouldn't surprise me if you purchased them at the same time, they probably came from the same batch, and the tolerance is likely based on batch to batch differences caused by process variations rather than random variations within a batch.

It is a little harder to understand/explain the fact that the low frequency side runs out of dynamic range at -60 dB and the high side gets there at 5 dB higher at -55 dB. Since these filters are symmetrical, have you tried swapping the input and output by turning the filter around at the fixture?

Also, you haven't really detailed your circuit for matching the 50 ohm of the VNA to the 330 ohm of the filter. If I were doing it, I would use a minimum loss matching pad. This would consist of a 54.281014769949586 ohm resistor (it is the value that the calculator gave - LOL) across the input and output coax to the VNA and a series resistor of 304.01167774007837 ohms up to the filter input/output. This would give a loss of 13.867585162369918 dB on each side. 5% values: 56 and 300. 1% values: 54.9 and 301. I am sure the 5% values would be just fine. You could bridge the filter location with a short on your test fixture to determine the exact loss through the pads, then place the filter in the fixture and easily find the filter insertion loss.


Radu Bogdan Dicher
 

Larry - I re-executed the calibration over 10.4 through 11MHz, saved to
"1," and I always recall it before measuring. However, the letter changes
every time I start the scan (from "C1" to "c1") - I press sweep, flop!, it
changes. Not sure why, as far as I can tell I have the same settings on
device and computer application (center: 10.7MHz, span: 600kHz), and I
RECALL 1 it every time I prepare for scanning.

David - yes, I am using 56.2ohm and 301ohms, 1% tolerance resistors. It's
the closest I could come up with by calculating for minimum loss. The
filters are 150kHz Muratas (JAs), but I also measured about four different
bandwidths, and from multiple sources. I have at least 7 or 8 different
batches and they all have the 5dB difference L/R. I think my calibration is
not getting applied, based upon Larry's feedback above.

Still trying to figure out how to maintain calibration settings while
executing the scan.

Thank you both,
Radu.

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On Sun, May 24, 2020 at 6:19 AM <david.hostetler@ieee.org> wrote:

What I see in the plot that you posted is a filter that is about 170 kHz
wide at the -3 dB points and centered at 10.715 MHz. This is consistent
with a Murata SFELF10M7HA00-B0 that has a spec of 180 +/-40 kHz and a
center frequency of 10.7 MHz +/-30 kHz. The fact that all the filters
exhibit the same response wouldn't surprise me if you purchased them at the
same time, they probably came from the same batch, and the tolerance is
likely based on batch to batch differences caused by process variations
rather than random variations within a batch.

It is a little harder to understand/explain the fact that the low
frequency side runs out of dynamic range at -60 dB and the high side gets
there at 5 dB higher at -55 dB. Since these filters are symmetrical, have
you tried swapping the input and output by turning the filter around at the
fixture?

Also, you haven't really detailed your circuit for matching the 50 ohm of
the VNA to the 330 ohm of the filter. If I were doing it, I would use a
minimum loss matching pad. This would consist of a 54.281014769949586 ohm
resistor (it is the value that the calculator gave - LOL) across the input
and output coax to the VNA and a series resistor of 304.01167774007837 ohms
up to the filter input/output. This would give a loss of 13.867585162369918
dB on each side. 5% values: 56 and 300. 1% values: 54.9 and 301. I am sure
the 5% values would be just fine. You could bridge the filter location with
a short on your test fixture to determine the exact loss through the pads,
then place the filter in the fixture and easily find the filter insertion
loss.