Ages ago, so long ago that the battery says use by 2016, I built the W7ZOI/W7PUA power meter from QST. See picture below - meter scale generated by meters.

I dug out the meter for an experiment recently, and needed the calibration data. I've lost the plots I made at the time, but do have the raw measurements from my logbook. Plots and measurements reproduced below for next time.

Frequency responsePower Response

Supporting data: