I love old industrial films. The Prelinger Archives at archive.org has all kinds, ranging from Sutherland right-wing propaganda cartoons to Coronet's films on the proper method of dating.
But here's one dealing with radio that's actually interesting. It's Behind Your Radio Dial and was produced for RCA/NBC in 1947 by Pathé, best-known for its newsreels.
http://www.archive.org/details/BehindYo1947
A trivia note .. director Edward J. Montagne went on to direct a bunch of McHale's Navy episodes in the 60s.
cArtie.