The New England QRP Club invites you to check in to our weekly net, join us at one of our gatherings, build a NEScaf or 79er, work WQ1RP, participate at NewEnglandQRP.org, or simply enjoy your QRP with our 73.
Have you ever wondered what the real power output of your QRP rig is? How about being able to measure QRPP?
Here's a circuit using two junkbox transistors and a garden variety op-amp that will let you accurately measure your rig's flea power down to milliwatts. It makes use of your ordinary shop multi-meter. If your DMM or analog voltmeter's accuracy is good, your results will be too. It works because power is proportional to the square of the voltage across a resistor, assuming the resistance stays the same.
Although it can't measure a rig's output power while operating into an antenna, it will tell you how much power your QRP rig puts out into 50-ohm resistive loads like a well-matched coaxial feedline. The best thing is that it's accurate!