nanovna-users@groups.io

Re: Homebrew sheilding

Thin brass solders easily with regular electronic solder (at least it did before they took the lead out). You might want to tin it along the edges you are soldering together. Also cuts fairly easily with ordinary scissors.

Re: NanoVNA #calibration

#13809

On run external program scan, calibretion data always rebuild, and use interpolation
Do not pay attention to it, if start stop freq some, no difference

Re: NanoVNA #calibration

#13808

I never change the frequency range (center/span) - at least, not
intentionally. I really only expect to be using this to sort IF
filters, and for these a range from 10.4 to 11MHz or so works pretty well.

If I leave everything alone and just insert a filter in my socket, the
device seems to execute a spontaneous scan, "C1" stays in caps, and if I
look on the device's screen, I still see the tilt (harder to read, as it's
on the small device screen, but if on the left side the trace matches a
horizontal grid line, on the right it goes right half way between two, and
higher).

If I run the scan from the Saver app, "C1" changes to "c1" but readings
stay very much the same, as far as I can tell.

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On Sun, May 24, 2020 at 11:13 AM Bill Cromwell <wrcromwell@...> wrote:

Hi,

I wonder if before recall a saved calibration we should do a reset first.

73,

Bill  KU8H

On 5/24/20 1:58 PM, Radu Bogdan Dicher wrote:
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 fourdifferent
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 calibrationis
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@...> 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 atthe
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 sidegets
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 atthe
fixture?

Also, you haven't really detailed your circuit for matching the 50 ohmof
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 54.281014769949586ohm
resistor (it is the value that the calculator gave - LOL) across theinput
and output coax to the VNA and a series resistor of 304.01167774007837ohms
up to the filter input/output. This would give a loss of13.867585162369918
dB on each side. 5% values: 56 and 300. 1% values: 54.9 and 301. I amsure
the 5% values would be just fine. You could bridge the filter locationwith
a short on your test fixture to determine the exact loss through thepads,
then place the filter in the fixture and easily find the filterinsertion
loss.





--
bark less - wag more



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Re: Homebrew sheilding

#13807

Dave,

I am curious how you soldered (braized?) the brass shim. I've been thinking about making my own shields (not for my nano) but am a bit intimidated by my lack of experience with brass.

Thanks,
Dave L

Show quoted text

On Sat, May 23, 2020 at 07:04 AM, Dave B wrote:


Hi just spent a UK windy afternoon confined to my radio 'shack' , so decided
to upgrade the screening on my 'basic' clone nanoVNA to see if the INPUT
'noise'  could be reduced.
I made the screens out of some 'shim' brass foil and formed them round some
srbp (Tufnol) formers THAT I made first.
I am pleased with the improvement that just a couple of hours 'metal bashing'
has produced.
Hopefully this will inspire others to have a go?
Dave

Re: NanoVNA #calibration

#13806

Hi,

I wonder if before recall a saved calibration we should do a reset first.

73,

Bill  KU8H

Show quoted text

On 5/24/20 1:58 PM, Radu Bogdan Dicher wrote:
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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www.avg.com
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On Sun, May 24, 2020 at 6:19 AM <david.hostetler@...> 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.

-- 
bark less - wag more

Re: NanoVNA #calibration

#13805

Big letter mean used calibration data stored in flash
If you change frequency, or use multisegment scan from NanoVNA saver or another program, calibration table rebuild and use interpolated values from main data
Big 'C' mean not interpolated values
Small 'c' interpolated

In most cases mo matter, interpolation good work if start/stop freq range not big

Re: NanoVNA #calibration

#13804

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.

<>
Virus-free.
www.avg.com
<>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

Show quoted text

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

Re: Calibration using Anritsu "tee" #calibration #solt

aparent1/kb1gmx

#13803

At HF the Anritsu tee is likely not going to be that much better a cal
as the supplied SOL.  To test it cal with the ANritsu Tee and then 
measure the supplies SOL.  Likely any difference you see will be 
due to the N to SMA adaptors adding length to the calibration plane.

At upper UHF it may make a difference.

Generally while good there is a finite level of accuracy available 
and you have to go to extremes to verify it.

Allison
-----------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

Re: Calibration using Anritsu "tee" #calibration #solt