Said,
I posted this procedure earlier that I used to check the gain of a RF preamp. The device under test was a Mini-Circuits preamp with a handwritten note saying, "27 dB gain, 1-1000 MHz".
Test procedure used:
1. Turn the amplifier on to allow it to warm up and also to guard against turn on transients damaging the nanoVNA during testing.
2. Turn on the nanoVNA, set the display to CH1/LOGMAG only, 10 dB per DIV, reference position at 4 divisions to be able to see 27 dB gain.
3. Connect a 20 dB attenuator to CH1 and a 6 dB attenuator to CH0 to closely match the expected 27 dB gain of the preamp.
4. Connect attenuators together using a cable. The nanoVNA should be displaying a 26 dB loss over the frequency range. If not your attenuators are not flat
5. Change to the calibrate menu and select "reset" and then perform a "through" calibration. The new reference should be 0 dB at 4 divisions.
6. Connect the output of the 6 dB attenuator to the input of the amplifier and output of the amplifier to the 20 dB attenuator.
7. Read the amplifier gain in dB directly off the nanoVNA using the marker display.
The above only checks the S21 performance of the preamp. That was all I was interested in at the time.
