San Juan Racing Association, the company that owns Washington radio stations WUST-FM and WJMD-FM, has agreed to purchase a Dallas radio station, KNUS-FM.

The Texas station and 43 acres of land it owns in the Dallas-Fort Worth area will be acquired for $4.14 million by SJR Communications Inc., a subsidiary of San Juan Racing, said Edward L. Cossman, executive vice president of SJR.

He said SJR plans to spend an additional $2 million to build a tall transmission tower on the land for KNUS and to offer use of the tower to other broadcasters.

Cossman said negotiations for the purchase of the Dallas station have been under way for several months, and should not affect talks under way for the sale of San Juan Racing to a group headed by Larry Israel, former president of the Washington Post Co.

Israel heads a newly formed broadcasting subsidiary of Coca-Cola of New YORK, A REGIONAL FRANCHISE SOFT DRINK BOTTLER, WHICH OWNS ONE TELEVISION STATION, @WIXT, in Syracuse, N.Y.

Early last month, San Juan Racing officials -- who include a number of prominent Washington businessmen -- said Israel's group had offered $66 million for the firm, which owns 10 radio stations and a horse racing track in Puerto Rico.

Among stockholders and directors of San Juan Racing are Robert Philipson, president of a Washington accounting firm; Raymond Dickey and Martin Willig, partners in the law firm of Danzansky and Dickey; and Joseph B. Danzansky, former president of Giant Food Inc., who recently became chairman of National Bank of Washington.

On Dec. 8, Coca-Cola of New York offered $20 a share for San Juan Racing stock that traded at the time of the offer for about $14.

Both the purchase of the Dallas station and the sale of San Juan Racing require the approval of the Federal Communications Commission.