After graduating from the University of Kansas in 1975. Mr. Callahan worked on the business side at three New York ad agencies before joining Fairchild Publications 10 years ago, climbing the corporate ladder there and moving on to ABC. In August 1991, Mr. Callahan was named to head ABC Radio Networks, the nation's largest radio network with 3,200 affiliates. The division of ABC/Capital Cities Inc. had revenue approaching $ 200 million last year.