Well, last night, I tweaked my recording program to produce recordings in 15 minute chunks and started it running. This morning, I had a bunch of recordings, a short run of which produced the following spectrograms (never tried this WordPress functionality before hope it works out!):

Addedum: Sigh. WordPress insisted on converting my nifty names (which told you what time they are recording) to shorter things, which didn’t preserve their relative ordering. Grump. Oh well. I think I got them sorted. By hand. How tedious.

Addendum²: Here’s W8LIW’s beacon, booming in quite strong.