This project was a quest to build a convenient connector panel for my bench power supply.

This is the 3rd in a series of continually improving designs for a high quality sampling head for making RF signal measurements.  The 1st and 2nd versions (and what they do) are described in this article.  This version has the best frequency range and power handling capability.

Today's experiment is a 10 MHz low pass filter to clean up a square wave and turn it into a sine wave.  This comes from the realization that the reference output from my Racal Dana 1992 universal counter is very unclean square wave instead of a pure sine wave.  Because square waves are actually composed of numerous harmonically-related sine waves, a good filter can extract just the fundamental tone of interest.  Cool, huh?

Why is this important?  Let's delve in a bit further . . .

This is a refinement to an earlier 40 dB coupler that I built in 2013.  That first one was taken directly from the May/June 2013 issue of QEX Magazine.  Inside, there was an article from Loftur Jonasson (TF3LJ / VE2LJX) about building a simple digital RF power meter.  Jonasson's article referenced and built on earlier work by W7ZOI and W7PUA (published in the June 2001 issue of QST).