Now that he’s retiring, Ron Hull has time to find out who he is. Not that he or anyone else in public TV is uncertain on that point. Hull is one of the field’s most prominent advocates for good programs and a memorable character who flips his tie over his shoulder when he gets excited, which is often. He worked most of 47 years at the University of Nebraska’s public TV network, leaving periodically and coming back again to its program side, which he tended while Jack McBride built the transmitters, the relationships and an array of ambitious projects based in Lincoln. Hull is retiring from half-time work at the university this month, but his to-do list is full: dedicating a study center for Nebraska author Mari Sandoz at Chadron State College, raising a million bucks for the Lewis & Clark Bicentennial Commission celebration in 2004, and tracking down who his parents were.