The House and Senate Armed Services committees agreed yesterday to authorize $36.1 billion to develop and produce weapons in fiscal 1978, including several President Carter does not want.

Chairman John C. Stennis (D-Miss.) of the Senate committee, in announcing the results of a week-long conference to work out a compromise bill, said the extra money voted for weapons will be offset by reductions in manpower.

The conference bill to be submitted to the House and Senate authorizes $270 million more for missiles, planes, ships and tanks than Carter requested. But Stennis said manpower cuts would bring the total $20 million under Carter's budget request.

House champions of building another Nimitz-class carrier rather than switching to smaller carriers as Carter recommended failed to get their way completely as the conference voted money to finance Pentagon studies of various options with an eye to making the decision between now and late this year.

But the end result of congressional actions this year on aircraft carriers is expected to be a budget request next January with no new carrier money.

Navy Itaders said they needed $6 million this year to design a smaller carrier, a request denied by the House Armed Services Committee, in order to have time to include one in the fiscal 1979 budget to be submitted in January.

A clear victory for the Navy came as the House-Senate conferees approved $20.1 million to continue work on Project Seafarer, and underground grid that would send radio waves deep into the ocean to communicate with submarines.

The Navy, despite strenous objections from environmentalists and many state officials, intends to transform its Seafarer test sites in Michigan and Wisconsin into an operating communications system. Opponents of Seafarer counted it would harm animal and plant life and interfere with civilian communications.

The conferees rejected the earlier House action authorizing $134.8 million for civil defense. The compromise figure is $95.5 million, $5.5 million more than Carter requested.

One weapon the conferees voted to keep building over Carter's objections is the A-7 attack plane built in Dallas by LTV, Inc. Carter had argued that it is obsolete but the conferees voted to build 12 more in fiscal 1978 and another 12 in fiscal 1979. Similarly, the conferees rejected Carter's recommendation to build only 78 F-15 fighters in fiscal 1978, raising the total to 108.

In offsetting the extra money authorized for weaponry, the conferees voted to cut the nation's active-duty force of service people to 2,085,100 a reduction of 3,900 from what Carter requested.

The Defense Department's civilian work force would have to be reduced by 12,100 people to reach the ceiling of 1,018,600 set by the conferees.

The Pentagon also would have to reduce the number of admirals and generals by 6 per cent over the three-year period of fiscal 1978 through 1980, and cut the number of civilians in Grades 13 through 18 by 6 per cent over the same period.