Fairfax County officials sweetened an already rich cable television pot yesterday by voting to offer franchise rights for the entire county to the highest bidder.

The Board of County Supervisors' 6-to-3 vote to change the bidding rules is expected to accelerate the already frenetic maneuvering to secure cable rights to Fairfax, which has a potential market of 200,000 subscribers worth an estimated $53 million over the next decade. Twenty-two companies have expressed interest in bidding for the cable rights.

Until yesterday, the board had indicated that the county's three market areas -- north Fairfax, south Fairfax and Reston -- would each be served by a seperate cable company.

But in a report presented by county staff, the benefits in increased competition and diversity of programming from such a three-way division was said, in view of a study of other cable systems around the country, to be "more hypothetical than real."

Vice Chairman Martha V. Pennino, who voted against changing the bidding rules along with Supervisors Marie B. Travesky and Audrey Moore, argued that her own investigation of cable companies indicated that the county would be well advised not to depend upon one source.

"As a rule," said Pennino, "companies receiving franchises have been slow in delivering (services). If county residents are going to be served well, it is going to take more than one company to do it."

Supervisor Joseph Alexander disagreed. He maintained that any cable company picked to serve the entire county would be investigated thoroughly enough to ensure its capability of providing fast and adequate hookups.

"This just makes it a little more cohesive," said Alexander. The county staff reported that it changed its opinion on the benefits of multicable franchises after visiting five municipalities with cable systems in June and talking to officials in three additional cities.Information obtained from those inquiries disproved prior estimates that multiple franchises stimulated competition and thus led to higher quality programs, the staff reported.

There is still the possibility that Fairfax County will be served by two cable systems when franchises are awarded early next year. The supervisors indicated that Reston might be awarded a separate cable system, but the rest of the county, which is still divided nominally into north and south markets, will be dealt to the one big winner in the high stakes cable competition.

County staffers argued in their report that the presence of Herndon and Vienna in the northern market made the coalition of the two halves of the county necessary. Both of those towns have expressed a desire to participate with the county in the cable system. But both also have maintained that if they were dissatisfied with the cable company that gets the franchise they might withdraw from the county and seek cable service from other companies.

Since both towns are in northern Fairfax, that withdrawal could leave that portion of the county a significantly less attractive marketplace for a bidder.

In action later in the day, the supervisors adopted a tough financial disclosure resolution that would require them and certain county staff members to state under oath in circuit court what interest, if any, they had in any cable television business. Lying undr oath is a felony punishable under Virginia law by a one-to-10 year prison term.

The supervisors also adopted a disclosure measure for franchise applicants that would require them to reveal their financial arrangements, including the names of so-called "rent-a-citizens" hired to be lobbyists and consultants.