United Television Inc. posted earnings of $ 5.18 million (49 cents per share) for the three months ended Sept. 30, 1992, compared to a loss of $ 96,000 (1 cents) for the like period last year.Earnings for the first nine months of the year rose 338% to $ 8 million (76 cents) from $ 1.83 million (17 cents) for the same period last year. Net revenues for the third quarter increased 7% to $ 26.1 million from $ 24.4 million last year. Net revenues for the nine-month period grew 3% to $ 81.6 million from $ 79.6 milion last year. The NASDAQ-traded company said increased ad revenues from political campaigns and the Summer Olympics as well as a substantial reduction in operating expenses , including a 39% decrease in programming expenses, boosted the company’s bottom line. Dividend and interest income for the quarter rose to $ 3.9 million from $ 3.4 million last year, and for the nine-month period to $ 10.8 million compared to $ 9.4 million last year.