One of basketball's longest running soap operas - Where will Ralph Sampson turn? - Is expected to end tonight when the 7-foot-4 Harrisonburg, Va., senior announces which college he will play for next year.

Sampson, who led Harrisonburg High to back-to-back Virginia AA championships, narrowed the field to four schools early this month and as late as yesterday rumors linking him with all four were still flying.

The four - Virginia, Virginia Tech, North Carolina and Kentucky - each claimed to have reason to hope that Sampson will name it at his 7 p.m. press conference tonight in his school gymnasium.

One rumor was dispelled yesterday: Sampson will not follow the recent pattern of many high school stars and join his coach as part of a package deal. Harrisonburg Coach Ralph Bergey is expected to sign with Maryland as an assistant to Lefty Driesell but the Terps are not back in the picture with Sampson.

In the circus-like atmosphere of the final hours, each of the four schools named to Sampson's final four were claiming the inside track yesterday.

Virginia supporters, pointing out that Sampson's parents want him near home and that Charlottesville is the closest of the four schools to Harrisonburg, said they believed Sampson's parents would win out and he would end up with Terry Holland's team.

North Carolina people insisted that Sampson wants to go out of state but remain in the Atlantic Coast Conference and all but decided on Carolina two weeks ago.

Kentucky rooters noted that Sampson spent much of his time at a weekend all-star game with Wildcat recruits and enjoyed himself thoroughly.

And Virginia Tech, considered by many to be the dark horse, was reveling in the fact that rumors that Sampson had signed with WPI grew so strong Tuesday night that Bergey called a North Carolina radio call-in show to deny them and to say that even he did not know where Sampson was going.

Less-partisan sources said they thought Sampson had decided on an ACC school but has not chosen yet between Virginia and North Carolina. Whenever Sampson goes basketball people are certain that success will follow. The slender senior is the most highly touted center to come out of high school since Moses Malone and the media was already massed in Harrisonburg yesterday awaiting the decision.