Re: Power Meter
Sam Wetterlin has some information on his web site on how to build a calibrator and the theory behind the circuit. It is the fifth paragraph down, under the title "MSA Documentation Relating to Hardware" http://www.wetterlin.org/sam/
I made a version for myself and there is documentation on my web page along with Gerbers for OSH Park under "Calibration Source for VNA, PHSNA, Scopes or Spectrum Analyzers" http://www.k9ivb.net/VNA/index.htm
There was also a spreadsheet and documentation in the old Yahoo Groups File area [not sure where it is here] on how to calibrate with a battery and a pot by applying the DC directly to the AD8307 inputs.