OK, so I have An AR8c, and two AR12cs. This is a constant on all of those devices. There are two specific frequencies, Approx 1220.0 and 2460.0. also a few lesser frequencies, but these are not prominent so can be ignored. ( see the link with the spectrogram from audacity displaying these. I have discovered that a good notch filter at both of those freqs will successfully kill the whine in post without any impact to the overall sound, , but this is an annoying workaround for an issue that, if you do a quick google search, you'll realize all of these AR series devices have.. I just wish I knew which part of the board was causing it. ALSO let us set a creation date for the SD card darnit!
https://bit.ly/4abjSbL