Over on the Tech Minds YouTube channel Matt has recently showed us his build of DL5NEG's super simple diode based RF power sensor. The device is designed to detect and measure RF power, using a DC voltage meter and a calibration curve which converts the voltage detected by the diode into dBm. The simple diode based design is remarkably accurate, and could be a useful tool for testing or calibrating SDRs.
Matt's first build uses a simple copper PCB board, and although it is low precision the results he achieved match up pretty nicely with the calibration curves. In Matt's second implementation he created a proper PCB design using KiCad and PCBWay. After soldering the components with hot air, he found that the results were just as good when he tested the power output of his AntSDR E200.
Matt intends to use this sensor along with a simple ADC connected to a Raspberry Pi to measure the power going into his QO-100 setup via a -40 dBm coupler.
This story was also shown Hackaday.