Radio: HAPPY BIRTHDAY MBS

Mutual Broadcasting System is seven years old this month, and a happy birthday it will be. Mutual will add two more NBC stations to its chain. The Federal Communications Commission's antimonopoly hearings which begin in Washington this week will not mar the youngest network's celebration, will probably be a sick headache for rivals CBS and NBC. Mutual's position is dandy. As a cooperative, it has little to fear from FCC's projected chain-busting.

Baltimore's WFBR and Pittsburgh's WCAE, MBS's two new outlets, were among the many stations being jogged around by NBC preparatory...