It's looking to me like my NanoVNA-H has an 87 ohm input impedance when I try to do a through measurement. Shouldn't it be 50?
Here's how I came to that conclusion:
I connected a 4.99k ohm resistor from CH0 to CH1,
Then I configured the NanoVNA as follows:
Display Format LOGMAG
Channel CH1 THROUGH
Then I did a calibration.
The display shows -35.2 dB.
The attenuation would be 10^(35.2/20) = 0.0173
Which means the NanoVNA's input impedance is 88.33(1-0.0173) = 87.5 ohms.
As a confirmation, I replaced the resistor with a 0.01 uF capacitor, and it was 3 dB down at 187 kHz, which is what I would expect for an input impedance of 87.5 ohms.
Am I doing something wrong here?
73,
Phil
