This device is part of my APRS radio transmitter backpack rig published later on.
PCB layout file, schematic diagram and AVR program available on GitHub: https://github.com/Juvar1/RFPowerMeter
It is designed with KiCad.
Here is second version of my RF power meter device. It has improved RF shielding and noise immunity. A little bit more expensive to make but quality pays.
C14 is also added for improving noise immunity from supply line.
Case is bought from Digi-Key. It’s part number is PIP-11766-C. DC jack outer diameter is 5.5mm and inner 2.5mm.