Here's a big surprise! During the summer of 1976, the somewhat stodgy WGBH-TV Channel 2, the PBS affiliate in Boston would not sign-on until 1 or 2 in the afternoon. They would fire up the transmitter at exactly 30 minutes before airtime. For the first 5 minutes you would get 3/4 bars and tone. Then.... they would start playing some of the Top-40 hits of the day on the audio carrier over the 3/4 color bars for the next 20 or 25 minutes before they began regular programming. Imagine hearing "The Theme from Laverne and Shirley" (Make All Our Dreams Come True) by Cindi Grecco, "More, More, More" by The Andrea True Connection and "Don't Go Breaking My Heart" by Elton John and Kiki Dee. Not exactly PBS material. But, sure enough (and I saw this myself back then) it did happen. I'm sure the higher-ups at 'GBH eventually told whoever to "nix the Top 40" before sign-on (or else.....). Sure enough, by the fall, nothing but 3/4 bars and 400 Hz tone was all you get on Channel 2, 30 minutes before airtime. (sigh....... )