I was fiddling with an OT+ the other day, trying to troubleshoot why I wasn't getting audio into the Kenwood TM-271 I was using for a transmitter. It turns out I had the PTT and Audio-out swapped - D'oh!
That's not the reason for this post, though. While testing with a scope on the audio out, I noticed that turning the test tone on and off left a sawtooth waveform of a few microvolts when off. Depending on when I turned the test tone off, I could get a flat line, or I could get the sawtooth. It never died down. I don't think it was a CPU clock artifact, either. I forget the frequency - I'll have to do it again. It was reproducible across several OT pluses I had sitting around, though.
APRS - Amateur (radio) Position Reporting System
- Tracing audio out of an opentracker plus.