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How find crystal filter terminaison resistor and capacitor

 

Hello,
I have a lot of 2 poles filters 20J26 Motorola and 45R15AZ.
I can¡¯t find the datasheet of these filters on the net, except on a site that tells me that the 45R15AZ is a 3rd harmonic filter, but no datasheet.
So I have no value of termination resistance and capacity.
In addition, if you take a common model like a 45M15A, you find different values depending on the manufacturer, it ranges from 560 Ohm/1pf to 4KOhm -1pf.
My question is whether we can measure these values with a nanovna or some other method.
and if you have the datasheet, put it.
Thank you
 

People seem to do it with variable resistors at input and output and tweak those untill the passband looks nice and flat.
Then the resistors can be measured with a multimeter to find out the impedance.
 

Gerard,
In addition to the variable resistance fixture method, there is provision in some firmware versions to mathematically modify the displayed data to show what the response would be in a system with Z0 other than 50 ohms.
I think that this feature is available only for the V2 and later versions because of the memory limitations in the original NanoVNA.
You can set Z0 to say, 330 ohms for typical 10.7 MHz ceramic filters. I don't know how well this would work at 4kohm.
The DiSlord firmware has the Port-Z setting in the DISPLAY menu. The ojisankoubou firmware has the Port-Z setting in the DISPLAY/SIMULATE menu.
--John Gord

On Sun, Aug 7, 2022 at 03:04 AM, Gerard wrote:


Hello,
I have a lot of 2 poles filters 20J26 Motorola and 45R15AZ.
I can¡¯t find the datasheet of these filters on the net, except on a site
that tells me that the 45R15AZ is a 3rd harmonic filter, but no datasheet.
So I have no value of termination resistance and capacity.
In addition, if you take a common model like a 45M15A, you find different
values depending on the manufacturer, it ranges from 560 Ohm/1pf to 4KOhm
-1pf.
My question is whether we can measure these values with a nanovna or some
other method.
and if you have the datasheet, put it.
Thank you
 

Gerard,
It looks like the latest H and H4 firmware from DiSlord also has the Port-Z rescaling.
--John Gord

On Sun, Aug 7, 2022 at 11:34 AM, John Gord wrote:


Gerard,
In addition to the variable resistance fixture method, there is provision in
some firmware versions to mathematically modify the displayed data to show
what the response would be in a system with Z0 other than 50 ohms.
I think that this feature is available only for the V2 and later versions
because of the memory limitations in the original NanoVNA.
You can set Z0 to say, 330 ohms for typical 10.7 MHz ceramic filters. I don't
know how well this would work at 4kohm.
The DiSlord firmware has the Port-Z setting in the DISPLAY menu. The
ojisankoubou firmware has the Port-Z setting in the DISPLAY/SIMULATE menu.
--John Gord

On Sun, Aug 7, 2022 at 03:04 AM, Gerard wrote:


Hello,
I have a lot of 2 poles filters 20J26 Motorola and 45R15AZ.
I can¡¯t find the datasheet of these filters on the net, except on a site
that tells me that the 45R15AZ is a 3rd harmonic filter, but no datasheet.
So I have no value of termination resistance and capacity.
In addition, if you take a common model like a 45M15A, you find different
values depending on the manufacturer, it ranges from 560 Ohm/1pf to 4KOhm
-1pf.
My question is whether we can measure these values with a nanovna or some
other method.
and if you have the datasheet, put it.
Thank you
 

Thanks for this comment Gerard.

I upgraded to from DiSlord 1.1 to DiSlord 1.2.00 on an H4.3 and it seems to work.
I tried 300 ohm as Zo and it moved the 50 ohm load to the place it should be on a 300 ohm Smith Chart.

So far so good.

73

Arie PA3A


Op 8-8-2022 om 03:40 schreef John Gord via groups.io:

Gerard,
It looks like the latest H and H4 firmware from DiSlord also has the Port-Z rescaling.
--John Gord

On Sun, Aug 7, 2022 at 11:34 AM, John Gord wrote:
 

Hi all,

this might be helpful.

[image: image.png]

[image: image.png]

R should be ~ 1 - 2 kOhm, noniductive.

73

Predrag, 9A3QV

On Mon, 8 Aug 2022 at 10:37, Arie Kleingeld PA3A <pa3a@...> wrote:

Thanks for this comment Gerard.

I upgraded to from DiSlord 1.1 to DiSlord 1.2.00 on an H4.3 and it seems
to work.
I tried 300 ohm as Zo and it moved the 50 ohm load to the place it
should be on a 300 ohm Smith Chart.

So far so good.

73

Arie PA3A


Op 8-8-2022 om 03:40 schreef John Gord via groups.io:
Gerard,
It looks like the latest H and H4 firmware from DiSlord also has the
Port-Z rescaling.
--John Gord

On Sun, Aug 7, 2022 at 11:34 AM, John Gord wrote:





image.png
image.png

 

Hi again,

and basic principle of the output impedance measurement.

[image: image.png]

Step 1. measure outpunt voltage V1 with no load (open circuit)
Step 2 terminate ouput with the known resistor
Step 3 Calculate Zout / Rout

[image: image.png]

73

Predrag , 9a3qv


On Mon, 8 Aug 2022 at 11:26, Predrag Pavo?evi? via groups.io <ppavosevic=
[email protected]> wrote:

Hi all,

this might be helpful.

[image: image.png]

[image: image.png]

R should be ~ 1 - 2 kOhm, noniductive.

73

Predrag, 9A3QV

On Mon, 8 Aug 2022 at 10:37, Arie Kleingeld PA3A <pa3a@...> wrote:

Thanks for this comment Gerard.

I upgraded to from DiSlord 1.1 to DiSlord 1.2.00 on an H4.3 and it seems
to work.
I tried 300 ohm as Zo and it moved the 50 ohm load to the place it
should be on a 300 ohm Smith Chart.

So far so good.

73

Arie PA3A


Op 8-8-2022 om 03:40 schreef John Gord via groups.io:
Gerard,
It looks like the latest H and H4 firmware from DiSlord also has the
Port-Z rescaling.
--John Gord

On Sun, Aug 7, 2022 at 11:34 AM, John Gord wrote:









image.png
image.png

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