Arlington County Manager Larry J. Brown proposed yesterday a $288.8 million budget for fiscal 1987 that focuses on public safety, community upkeep, language programs for foreign-born residents and affordable housing.

"I think we can do more than we've done before and still maintain a stable tax base," said Brown, whose budget calls for no increase in either the real estate or personal property tax rate.

The proposed budget, presented at a County Board meeting yesterday, represents a 6.7 percent increase in current spending and takes into account an anticipated loss of $2.8 million in federal revenue sharing and other funds.

It includes a $236.5 million general operating fund -- a 5.6 percent increase over this fiscal year -- that is supported largely by local tax dollars.

"Arlington is not in the same kind of position a lot of other local communities are in," said Brown, explaining that the anticipated 12.4 percent increase in the county's tax base -- most of it in commercial properties -- is expected to help ease the sting of federal cuts.

The budget proposal calls for improvements ranging from increased community inspections and tree plantings to two new police vans, increased funds for English-language classes for adults and a continuation of housing subsidies for the poor and elderly, which were formerly financed largely by federal aid.

The budget calls for a major reorganization of the county's second largest department, community affairs, into two departments that Brown said would increase the county's ability to provide recreational, planning, inspection and housing services.

The proposed budget does not factor in potential decreases in federal money resulting from the Gramm-Rudman-Hollings budget legislation because of uncertainties about the measure's fate. On Friday, a special federal judicial panel in Washington declared a key part of the law unconstitutional and an appeal to the Supreme Court is expected.

The budget also does not take into account possible cuts incorporated in the proposed federal budget.

Mark Jinks, the county's budget director, said adoption of that budget would lead to cuts "in some way, shape or form" in every county program receiving federal aid. The state, he said, is not expected to pick up the slack.

The budget projects $9.4 million in federal funds, down 20 percent, and $28.5 million in state aid, down 2 percent.

In anticipation of threatened federal cuts, Brown has proposed adding $500,000 to the general contingency fund, for a total fund of $3.5 million. Of that, about $2 million is earmarked to make the pay scale for county employes more competitive with neighboring localities.

Anna Lee Berman, director of the county's department of management and finance, said revenues are expected to exceed Brown's spending plan by $3 million. That cushion, she said, will give the County Board more leeway to offset federal cuts, decrease tax rates, or make improvements in county and school programs in the fiscal year that begins July 1.

"Clearly, this is going to be a difficult budget year for us," County Board Chairman Mary Margaret Whipple said yesterday. "In spite of our relative prosperity, there are many community desires for services that we're going to have to make hard choices on."

Under the proposal, the average $124,315 single-family house this year will jump 4 percent in value, to $129,288, and the tax bill will increase $47, to $1,228, based on the current real estate tax rate of 95 cents per $100 assessed value.

The budget proposal sets aside $5.6 million for cost-of-living increases for county and school employes, which may be between 3.2 and 3.6 percent. Brown and Superintendent Arthur W. Gosling are to confer on the exact increase.

Included in Brown's budget, as a starting-point figure, is $59.6 million to operate the school system, another $1.3 million for school capital projects and $2.5 million for facilities and programs jointly run by the county and schools, such as the high school-community swimming pools.

The school system's proposed base budget for the next fiscal year calls for $61.8 million in county funds, a figure drafted before school officials learned of a potential $600,000 cut in state aid. In recent years, the County Board has granted the schools' funding requests.

The proposed $10.5 million county share to operate the Metro transit system is up $500,000 because of the planned opening this year of the East Falls Church station on the Orange Line, the only unopened county station.

Besides the program improvements included in the base budget proposal, Brown prepared an unfunded "wish list" of projects totaling more than $2.5 million and requiring 70 new positions, some of which the board may approve when it adopts the budget April 26. Among the proposals are:

*Hire 13 police officers to improve security and responsiveness in the county's high-rise development corridors and in the Shirlington/Nauck area.

*Hire extra personnel for gypsy moth suppression, inspections of existing buildings, landscaping and impoundment of abandoned cars.

*Increase housing grants to low-income persons and hire someone to help recipients of federal housing subisidies find low-cost housing.

*Expand the county's English language training program and hire someone to coordinate the various county services for the foreign-born community