Greetings! I listened here from upstate South Carolina for about 2
hours during the listed times continuous, on both frequencies and heard
nothing.
I listened on the GE Super Radio II, and the RS DX-396. Both are
pretty good on Medium Wave, but alas nothing I could possitively ID.
It did sound like on the 690 frequency I might have heard some morse,
but nothing I could hear on record.
Nice experiment though. I was hopeful being from SC that I might hear
it. Conditions were pretty good here, although I have had some
electronic interference on some frequencies since our recent ice storm
and week of lost power.
Thanks for passing on the tip! Have a great New Year! Jon in South
Carolina.