The pilot reported that the takeoff was normal. As he attempted to adjust the pitch attitude during climb out of ground effect, the control yoke locked in position and could not be moved fore or aft. He aborted the takeoff and porpoised the remaining 1,500 feet down the runway collapsing the nose landing gear. A postaccident examination by two FAA inspectors failed to find any type of control interference. The inspectors reported that the company station manager said the pilot had initially reported 'odd vibrations' just before the abort.