An Arlington-based public broadcasting station will not have to dismantle the radio tower it extended beyond the permissible height, but it will have to follow several conditions set by the County Board to help allay nearby residents' concerns about the tower and emissions from microwave dishes on it.

Any future changes to the tower owned by the Greater Washington Educational Telecommunications Association (WETA) will require County Board approval, the County Board said, instead of a lower-level review. The board said the station also must pay for semiannual radiation tests on the dishes.

The board imposed those and other conditions after two lengthy hearings, one in September and the other last week, when it heard occasionally bitter testimony from neighbors about the relationship with WETA.

The latest dispute erupted over the extension of WETA's FM-91 radio tower at 5217 N. 19th Rd., to a height of 496 feet, or 21 feet higher than allowed in the tower's use permit.

The extension was permitted because of a clerical oversight by the county. Rather than tear down the extension, which had led to the strengthening of the full tower, WETA requested a use-permit amendment.

The process of obtaining that amendment opened a forum for neighbors to complain about the station's treatment of the neighborhood and its agreement to lease space on the tower for six microwave relay dishes that GTE-Sprint mass telecommunications uses for its long-distance telephone system.

Although the county has received reports that emissions from the microwave dishes posed minimal risks, neighbors complained of potential health threats and of noise, trash and parking problems they have encountered because of WETA's proximity.

"This is not a public service," said neighbor R.C. Mozingo of the nonprofit WETA. "This is an outrage."

Ward Chamberlin, WETA's president, acknowledged that "it's not pleasant having a tower sitting over your house. We realize that. And in some ways we haven't been as good neighbors as we should have . . . . But we're going to do our best to make [the future] as pleasant as possible."

Between the two County Board hearings, the neighbors and WETA arrived at agreements on several issues, including soundproofing, landscaping and property access, said James R. Michael, a WETA attorney.

County Board members, expressing distress that the extension permit was improperly approved, gave WETA a one-year use permit but stipulated that the station would have to go in for renewal sooner than that if the radiation tests showed higher-than-expected levels.

"I share your concerns," board member Michael E. Brunner told the residents in introducing the motion that the board adopted. "Had we to do this over again, I wouldn't have allowed a lot of it."