I grew up in KCK and my dad listened to it almost every night for a few minutes seeing if it would change. It never did. My oldest son now listens from time to time. I am 38, the haunting sounds of morse code has been there as long as I know. Also, I don’t know anybody that knows why!
:D:D:D:D
Stumbled upon this thread while searching about nearly the same thing I heard on my a.m. radio near the 530 slot, except this was approximately 1992 and in E. Moline, Illinois. Always impressionable, I fancied it was time travel communication. (sounded like ‘SOS’. ) 
Would this count as a double zombie?
Yeah, and I, for one, welcome our new overlords (again !)
The code for Quad Cities airport is MLI. That’s --. .-. …