On Sun, Feb 9, 2025 at 02:04 PM, John Gord wrote:
A crystal (or ceramic) filter response is correctly transformed by the
renormalization; I have used this feature several times.
Interesting... What was the design impedance of the filter?
I am surprised at your results because the loading greatly affects the crystal filter characteristics. The usual way is to use a series resistance, L pad or transformer on input and output if the crystal filter is designed for a higher impedance and then recalculate the response from the measured results factoring this in. Doing this is not the same as directly connecting a 50 ohms VNA and then doing a S parameter transformation (Port Z function) like the one in the NanoVNA. I am interested in your results so please explain the test setup and your results.
Roger
Roger Need