The Fairfax County Board of Supervisors yesterday praised the $1 billion budget proposed by County Executive J. Hamilton Lambert and gave it preliminary approval with only minor revision.

Despite intense lobbying by teachers, the board did not even consider appropriating more money to increase their salaries above the 3 percent limit it approved earlier for other county employes. The board did, however, vote to give some policemen raises and to spend money on subsidized housing at the Circle Woods development near Fairfax City.

The board is scheduled to take a final vote on the fiscal 1984 budget next Monday. Yesterday's vote indicates that it will formally approve it largely as Lambert proposed, without any increase in property tax rates. Taxes currently are set at $1.47 per $100 valuation.

Supervisor Thomas M. Davis, a Republican from the Mason District, described Lambert's budget as "lean and mean." Supervisor Sandra L. Duckworth, a Democrat from Mount Vernon, agreed that it is "very tight," and said she is delighted "that we didn't have to raise taxes or cut programs."

The board did vote four changes totaling $508,506 proposed yesterday by individual supervisors. The largest addition made yesterday was $255,000 to convert 17 town house units at the controversial Circle Woods project from low-income rental housing to moderate-income sales properties. The county will have to pay additional costs for the conversion since that program is not federally supported.

Supervisor James M. Scott, a Democrat from the Providence District, who represents the Circle Woods area and proposed the appropriation, said the new plan would depend on federal approval.

The board also agreed to add $191,506 to give raises to police who have reached the top level for patrolmen who cannot or do not want to take supervisory positions. Under the plan those patrolmen could make from $19,703 to $29,111.

It also approved an additional $634,702 that would fund new projects, such as gypsy moth and mosquito control programs, which the supervisors approved after Lambert drafted the budget.

In addition, the board approved revenue revisions expected to give the county a surplus of $6.65 million at the end of the coming year. James P. McDonald, deputy county executive for management and budget, advised the board not to spend the surplus, warning that the county faces a potential loss of $8.8 million in state and federal funds.

McDonald also said there is no money in the budget for the proposed county-owned bus system that would operate around the Huntington Metro station south of Alexandria, scheduled to open in late 1983. County staffers estimate that buses and garage space for the system, still in the planning stages, could cost the county $5 million to $6 million.

Supervisor Audrey Moore, an Annandale Democrat, disputed Lambert's assertion that county spending has only increased 5 percent in the fiscal 1984 budget and said that the actual increase is closer to 8 percent.

"I'm only pointing this out because this year we're really holding the line. We can't hold the line on cost-of-living every year," said Moore. She predicted that in future years the increase could be four or five times as great as the current increase.