Technical problems have raised the cost of the proposed U.S. antisatellite weapon and again stretched out its testing program, according to data presented to Congress by the Air Force.

The long-delayed first test of the system against a target in space, once scheduled for last fall, now is planned for late July, according to sources. The target, two metallic balloons attached to an orbiting satellite, is scheduled to be launched next month.

The House Armed Services Committee has further complicated development of the system by cutting $48 million from the $149 million requested for research next year. That reduction, if approved by Congress, would make it impossible for the Air Force to complete the test program by the end of fiscal 1987, as planned by Pentagon officials.

The system consists of an F15-launched rocket that carries into space a device that homes in on a satellite, destroying it on impact.

Congress last year limited the Air Force to three tests of the new weapon, with members arguing that development of the U.S. system would open a new type of space arms race.

The Reagan administration, however, argues that the Soviet Union has had an operational weapon for 10 years.

The Air Force, which has had electronic problems with the system, has been cautious with the first test against a target in space, fearful that a well-publicized failure could hurt the space defense program.

Several legislators are planning to press for a moratorium or a limit on antisatellite tests, according to congressional sources. In the past, the Air Force has said it would take at least 12 tests to be certain the system is ready.

Sources said it may be impossible for the service to carry out a second test of the weapon against the balloon target in space during the current fiscal year, which ends Sept. 30. Originally, the Air Force had planned for three tests this year.

The Air Force told a Senate Appropriations subcommittee that $92 million being sought to obtain antisatellite missiles next year would provide for only two, according to Military Space, a space weapons newsletter.