An agreement to finance a new Washington television station, Channel 50, has been reached by Washington businessman Theordore Ledbetter representatives of Texas oil millionaire Clint Murchison Jr. and Field Enterprises Co., it was announced yesterday.

The station will offer a combination of pay television fare -- such as movies, entertainment and sports -- and free local programming as soon as next summer.

The deal was announced by Ledbetter, an engineer, filmmaker and one-time station operator in U.S. Virgin Islands who won Federal Communications Commission approval last June to construct Channel 50 here. At that time, Ledbetter had an agreement with Teleprompter Corp., the nation's largest cable system operator.

After Teleprompter officials concluded that they were not interested in major involvement in the subscription television business, Subscription Television of America, the Murchison-controlled private firm, and Field Communications, a subsidiary of Field Enterprises Inc., joined in a 50-50 agreement to form Subscription TV of Greater Washington to finance the project. Field owns The Chicago Sun-Times and five UHF television stations.

Ledbetter, 40, holder of most of the company's stock, hopes to have the television station on the air in the summer, splitting the air time between local programming and a pay television service offering films, concerts and sports. He would be the only black operating a television station in the area.

After building the facility, he still must receive his FCC license to broadcast. The station's startup date is dependent on acquisition of the antenna and other equipment that requires a long period of time from order to delivery.

Subscription television (STV) is a broadcast service that sends scrambled ultra high frequency (UHF) or very high frequency (VHF) signals over the air to home television sets equipped with a decorder, enabling the viewer to watch the broadcast. Nationally, the industry's 15 operating stations expect to have an audience of almost 850,000 by year's end.

Channel 50 will operate conventional UHF service from early in the morning to roughly dinner time. No decoder will be necessary to receive programming during those hours. But at that point the pay service, costing $20 a month, will take over the station.

Installation of the equipment is expected to cost between $40 and $50, with a deposit of about $50 required, Ledbetter said. Homes without the decoder will see a scrambled signal as a voice explains the available pay service.

Ledbetter said it would cost about $3 million to build the Channel 50 facilities. But the financing partnership for the station will put up as much as $30 million for home decoding boxes for 200,000 homes and for the staffing by 100 to 150 technicians to install and service the equipment, according to H. Brian Thompson, president of Subscription Television of America.

Thompson said the company would offer programming similar to its San Francisco station, and would be interested in bidding for possible rights to local professional and college sports.

STV has a station in operation in San Francisco and also is involved in licenses for stations in Chicago Atlanta. Providence and Norfolk. Field Communications, which is based in San Francisco, operates UHF stations there and in Chicago, Philadelphia, Detroit and Boston. Field recently bought its first cable television franchise in Southern California.

Ledbetter expects to complete negotiations with the District police department shortly to lease space on an existing 455-foot television tower at Georgia Avenue and Peabody Street NW.

The station's signal, he said, could reach Baltimore, although Ledbetter and Thompson said the initial marketing of the service would focus on Washington. Within a 50-mile radius there are about 1.5 million homes that could receive Channel 50.

Thompson said the two financiers plan to have an "arm-length" relationship with Ledbetter, who said he plans to operate Channel 50 with an emphasis on community needs, which he says existing Washington-area media do not fill.

"Most of Washington's media treats Washington as the nation's capital," Ledbetter said. "We will treat the city as a place where people work and play. We want to encourage local television, professional filmmakers and producers and everybody who is not making television here now to work with us."

Ledbetter said he has a unique opportunity to do that because the revenues from the pay service will fund his operation of Channel 50, leaving him free to assemble virtually uninterupted educational and community-oriented programming. He emphasized that he is not in the business to attempt to match the large revenues of commercial stations.

"I'm choosing not to go that route, because I think television is too commercialized," he said. "People are trained to be consumers. This is an alternative. I want to provide the kind of service" that will help people with their business and hobbies.

We're not going to do black programming," he added. "Our station will be more for people who have a certain life style and set of interests, black or white, people who want to make all their dreams come true."

The announcement moves the establishment of Channel 50, the subject of a long financial and regulatory wrangle, closer to reality.