HOME SHOPPING <HSN> TO PURCHASE TV STATION Home Shopping NEtwork Inc said its Silver King Broadcasting Co INc unit entered a definitive contract to buy the broadcasting assets of TV station KWVT, Channel 22 in the Portland/Salem, Ore. area for undisclosed terms. Additionally, the company said KWVT, which serves 785,000 homes, began broadcasting Home Shopping Network full time this morning under an affiliation agreement. Home Shopping also said it entered a definitive contract to buy TV Station KPST, Channel 66 in San Francisco and KLTJ, Channel 49 in Dallas.