I made a stab at some measurements back when we were first getting me onboard with the test. My thought was to compare the signal coming from my scanner, which wasn't being recorded, to the signal coming from the Baofeng, which was recording just fine.

Audio sidekick board partial schematic. I measured at TP5 with trimmer RV1 at its default setting. I honestly can't say what I found -- I didn't write it down. I do recall that the scanner audio signal was much lower than the 800-mV p-p specified above, and that the Baofeng output was much higher.

The reason I got poor numbers (that I don't remember) was because I was measuring the audio for whatever was being said on the radio at that moment. I feel like I need a simple sine wave coming from the scanner to accurately assess what's going on at TP5 with my oscilloscope. So, step one is to build something that can send an audio sine wave to the scanner (or the Baofeng) so I can get an accurate measurement for each.