Montgomery County Executive Charles W. Gilchrist yesterday unveiled an $818.7 million budget that had something for almost everyone, including new funds to create a high-technology job training corporation, slightly more money for the public schools and parks and, as an added bonus, a three-cent decrease in the property tax rate.

Gilchrist was able to increase money for his pet programs and still lower the property tax rate by squeezing more revenue out of some nontraditional funding sources. Fees for many county services will increase, from the cost of reserving a book at the county library to the cost of health care at a county clinic. The county also plans to make about $4 million by selling off some surplus abandoned school properties.

"We have met our obligation to live within our means," said Gilchrist, who highlighted his budget at a morning briefing for reporters, surrounded by huge green and white charts of revenues and expenses.

The budget, for the fiscal year beginning in July 1984, represents a 4.1 percent increase over last year's budget of $786.3 million. It is also well within Gilchrist's own strict December guidelines, back when the county was predicting a possible $11 million shortfall. The new fees, coupled with higher-than-expected tax collections, helped erase that shortfall, Gilchrist said.

The budget is likely to face some tough scrutiny during the next few weeks of public hearings, before the County Council adopts a final version in mid-May. The budget would slash the county's work force by 92 full-time and 140 part-time positions, although Gilchrist said the county government can probably find jobs for all but about 10 of the people filling those positions.

Also, Gilchrist ignited an annual controversy by cutting $5 million from the school board's requested $372 million, a cut that could mean 200 teacher layoffs, school officials said. Gilchrist proposed $367 million for the schools, a $13 million increase over this year's budget, and he promised to "resist very strenuously" any council attempts to increase that amount.

But school board spokesman Ken Muir said, "If we get cut back to that level, it's going to mean we lose all our improvements."

Despite the three-cent decrease in the property tax rate, homeowner tax bills will increase an average of 8 percent across the county, county officials said, because of inflated real estate assessments. For example, the tax rate for the owner of a $100,000 home in Kensington will go from $3.19 to $3.16. But because his property will be reassessed for fiscal year 1984, his tax bill will jump from $1,696 to $1,830.

Gilchrist wants to hold the Maryland-National Capital Park and Planning Commission to a slight 1.9 percent increase, well below the inflation rate. He gave the commission a slight $750,000 more than he had recommended initially in December, for a total of $23.7 million, but that amount is still well below the $25.3 million the agency is requesting.

"This budget) calls for greater reductions on the part of park and planning than for any other agency," said agency spokesman John Hoover. The park and planning commission has already approved new user fees for sports teams wishing to use special and regional parks--$36 per game.

Gilchrist is planning to fund his budget with at least $1 million in new user fees, and also by improving collection on some existing fees. Six of 11 county departments, essentially every department offering services to the public, have been told to consider establishing new fees or raising current ones. Many programs are still under scrutiny.

But some increases have been decided. The cost of reserving a book at the public library, for example, will increase from 15 cents to 50 cents, under Gilchrist's plan. The health department will begin charging a $4 flat rate for most basic services. Currently, the department has a sliding scale fee that was rarely, if ever, collected.

Also, convicted drunk drivers sent to court-ordered alcoholism classes will have to start paying for their treatment--$100 for a five-week educational class, and $300 for 21-week intensive therapy.

Gilchrist managed to find money to increase funding for programs reflecting his own priorities.

Senior citizens will find longer hours at one senior center, and an additional site for the senior nutrition program. An appropriation of $250,000 was included to begin coordinating efforts to help "deinstitutionalize" the mentally retarded and place them in the community. And money was increased for revitalizing downtown Wheaton, cutting public grass and fixing potholes.