Gerard,
The latest DisLord firmware for the NanoVNA does allow you to see what the filter response would be with a load impedance different than 50 ohms.
First perform an SOLT (short, open, load, through) calibration right at your filter test point. Then connect the filter: You should see a somewhat distorted band-pass response at the nominal filter center frequency (use a span about 4 times the nominal filter width).
Then use the PORT-Z setting in the DISPLAY menu. Set it to something like 500 ohms and see if the filter response looks flatter in the pass band. Adjust the PORT-Z setting until you get the flattest response.
You can try adding a small capacitor (a few pF) to ground to see if it improves things.
Once you get an approximate value for the filter design impedance, you can design some simple L-match sections to measure the response more accurately. Some iteration may be required.
--John Gord
On Sat, Sep 17, 2022 at 09:59 AM, Gerard wrote:
Hello,
How to find the values of the "Terminating impedance" of a filter 2 poles.
(values of resistor and capacity)
I have 2 models, but I can¡¯t find the values on the Net (45R15AZ; motorola
20J26)
Is it possible with a NanoVNA? or other?
cdt
On Sat, Sep 17, 2022 at 09:59 AM, Gerard wrote:
45R15AZ
