This one is a prototype. I screwed the board up on this cycle (SMA footprint) but it works and is dirt cheap (under £10!). Decided to put together a proper RF power meter as most of the stuff from China is junk. That doesn't mean the parts are junk but the way they put them together is.
This is an evolution of the W7ZOI power meter here:
https://www.vintage-radio.net/forum/...d.php?t=144088 ...
The original one suffered from a few problems. That was mainly due to the layout. Secondly it was poorly decoupled. Thirdly it was badly constructed. Fourthly, the output transform circuit actually pretty much made it useless. It was a hack job.
Now we have version 2...
Calibration is done as follows: Apply 0dBm. Record the voltage on the DMM here to get the 0dBm intercept. Stick a 20dB attenuator in line (or crank generator down by 20dBm) and record the difference in voltage. This gives you a y=mx+b transformation.
Calibration is pretty much 100% linear and it has 60dB dynamic range which is good for most tasks with suitable attenuators and/or taps.
Currently waiting for a suitable signal generator to appear so I can check it across a wider frequency range than my AWG kicks out. It's flat across 2-25MHz though.
The board is designed to fit inside a specific hammond enclosure with a pigtail on one end. Once I've fixed the boards and get hold of a signal generator, I may be offering this as a kit. Time will tell!
Edit: also to note, the output buffer and filter is designed to respond fast enough to allow a sweeping signal to be applied from the generator. This allows you to use this to do antenna (with return loss bridge) and filter sweeps with a sweeping generator and get a log-log output on a scope this turning it into a scalar network analyser too!