Whatever else they may have been saying when they cast their ballots in Tuesday's elections, Montgomery County voters made it clear what they didn't like.

By a 5,000-vote margin, they rejected a measure that would have sharply cut back property taxes and local government revenues, while simultaneously approving a more restrained measure to curb increases in the county budget.

They also rejected, decisively, the policies and programs of the county Board of Education and its superintendent. Charles M. Bernardo, and installed a new "back to basics" majority on the county's seven-member school board.

"There was a lot of dissatisfaction with the system in many ways that the conservative candidates were able to capitalize on," said retiring school board member Herbert Benington. ". . . [The voters] were unhappy because they thought basic academic subjects were not being taught. They thought that some students were not doing anything and ought to get shaked up."

On other issues, however, voters tempered any desire for change with restraint. By rejecting the tax-cutting charter amendment TRIM and approving instead a measure restricting county budget increases, the voters called for a curb on government growth but entrusted their elected officials with the job.

"They fired a gun across the bow in saying they're concerned about inflation, but they said they didn't want the problem taken care of with a meat cleaver," said former Democratic Party chairman James Doherty.

The magnitude of frustration with the county's government, however, was not nearly so great as some Democrats had feared and many Republicans had hoped.

Democratic state Sen. Charles W. Gilchrist easily won election to the county executives's post, and will become the first Democrat in that job since it was established eight years ago.

In choosing Gilchrist, the voters selected a candidate committed to running things with a "steady" hand and making "measured" decisions, rather than choosing the program of government overhaul and drastic tax cuts advocated by Republican candidate Richmond M. keeney.

At the same time, seven Democrats - including four newcomers - were elected to the County Council by comfortable margins continuing the eight-year-old tradition of all-Democratic councils.

"They (the voters) said our incumbents have done a good job but they want us to be a bit more careful," said incumbent Esther Gelman.

The general satisfaction Montgomery voters appeared to feel with county government clearly did not extent to their local schools. Members of the new conservative majority elected to the Board of Education have pledged to fire Superintendent Charles M. Bernardo and redirect many of his programs.

Observers on both sides of the bitter campaign between the conservative group - Joseph Barse, Carol Wallace and Eleanor Zappone, and the more moderate Team for Positive Action - which elected only incumbent Elizabeth Spencer - attributed the success of the winning slate to the careful, professional organization of their campaign.

Barse, Wallace, Zappone and board member Marian Greenblatt have been working together since 1976, when they campaigned against Montgomery County's school busing system.

Unlike Spencer, Nancy Weicking, Sandra King-Shaw and Frederica Hodges, who were associated with the county PTA and school board establishment Barse Walase and Zappone waged an aggressive campaign founded on simple, direct promises.

They said they would fire Superintendent Bernardo, cut back on administrative personnel, slow down school closings, do away with elaborate academic programs and most importantly, "reinforce the basics."

Supporters of the opposing slate said yesterday that it was crippled because the moderate candidates refused to match what they considered to be broad, simplistic promises.

Some observers predicted that the new conservative majority on the board of Barse, Wallace, Zappone and Greenblat would shift the board's policies more drastically then any group in almost two decades.

The first test of their campaign promises apparently will come with their attempt to dislodge Bernardo, whose original contract extends through October 1979, and who was granted a new, four-year contract by the present board last June.

The legality of the contract renewal is now being tested in court by the Montgomery County Education Association. Unless the courts rule against him, however, Bernardo apparently will not leave voluntarily. Yesterday, he issued a statement saying that he had "every intention of serving the schools throughout my second term in office."

Another county official whose future is in some doubt in the wake of the election is Police Chief Robert J. diGrazia, who was criticized by Gilchrist during the primary election campaign. Gilchrist said diGrazia was responsible for "disturbingly low morale" in the department, but later in his campaign the Democrat shield away from discussing the police chief.

Yesterday, while many police officers were anticipating diGrazia's eventual departure, the chief was taking election developments in stride. "The police officers may be ecstatic today, but there is no moving van at the back door," a spokesman quoted the chief as saying.

The face of the county's legislative delegation changed somewhat, but not drastically, in the wake of the elections. There are eight new members on the 26-member delegation, and Republican representation was quadrupled - going from one to four.

Three of the Republicans - Constance Morella, Luiz Simmons and maverick former Democrat Robin Ficker - had all run for office unsuccessfully on previous occasions.

The defeat of TRIM, which four weeks ago supporters and opponents believed was heading to victory, was attributed to the massive political organization by the Fair Share Coalition.

he coalition of labor, teachers, civil rights and senior citizen group and government employes warned that TRIM's $47 million budget reductions would mean losses in the abundant services in libraries, schools and public safety that county residents had long supported.

"It was their scare tactics that defeated TRIM," charged Bob Brennan, a wealthy and well-known Republican builder who was defeated in his race for a council seat.

TRIM, or Ballot Question E, proposed by the Montgomery County Taxpayers League, would have rolled back property tax rates 35 cents to $2.25 per $100 assessed value.