Here is a collection of sign-on and sign-off recordings from Central Iowa radio stations. Cal Bierman, on of this site's most loyal contributors has provided these interesting and historical recordings.
He actually provided more, but for the sake of conserving bandwidth, we are providing a sampling of the recordings.
Sigh- on and sign off of Des Moines radio stations 50's - 80's (Streaming MP3 - RealMedia player not used)
Courtesy of Cal Bierman
Audio Oddities page
DesMoinesBroadcasting.com home page