[BC] Class "D" AM Towers

[Tom Taggart]

RE: Class C (Class IV) DA's...

These channels were originally limited to 250 watts. In the 60's, the  
Class IV stations were allowed to increase daytime power to a  
kilowatt, but were required to accept interference from other Class IV  
stations on the same channel.

They were not allowed to increase power if they caused interference to  
adjacent channel stations, usually regionals.  Hence a number of these  
Class IV stations elected to go directional daytime to protect those  
adjacent channel stations.