TVX Broadcast Group Inc., owners of five independent Taft Broadcasting Co. stations, including Washington's WDCA, missed a Dec. 31 deadline to repay $200 million to Salomon Brothers Inc., which lent the money to the Virginia Beach broadcasting company last April to purchase the stations.

Salomon Brothers has extended the deadline to Feb. 1 to keep TVX from defaulting on the loans, according to a filing with the Securities and Exchange Commission. It also has lent TVX an additional $7 million, according to Tim McDonald, president and chief executive of TVX.

McDonald said TVX had planned to sell high-yield bonds before the end of the year to repay the entire $248 million bridge loan it received. "But we ran into a little hitch on Oct. 19," he said, referring to Black Monday, when the stock market plunged 508 points.

"In the aftermath of the stock market crash, we have not brought the financing to market," he said.

If market conditions are not right before Feb. 1, McDonald said TVX will probably ask for another extension, and he said he expects no problem in receiving it. He declined to speculate on the timing, saying only that "bond prices are a little high right now, but they're do-able."

Salomon Brothers declined to comment.

McDonald is a former Washington television executive who worked at channels 5, 9 and 20 before starting the broadcasting company in 1979. The company now owns 12 television stations.

TVX took control of WDCA, Channel 20, on April 9, along with stations in Philadelphia, Miami, Dallas-Fort Worth and Houston. Since the sale, TVX has slashed personnel at Channel 20 and the other four stations. Two years ago, WDCA had about 119 employees; it now has about 45.

McDonald said personnel were cut at all the stations to reduce expenditures.

He also said that revenue has risen at all five stations. At WDCA, he said, revenue will rise 11 percent this month over January 1987.