The Boy Scouts were attracted by the Cyrillic script on the oddly-shaped packet they spotted floating in the Pacific Ocean off the West Coast of the United States.

But closer examination by American intelligence agencies found more of interest than the strange writing on the waterproof packet. Inside was a Soviet acoustical detection device utilizing exact copies of some of the latest U.S.-made microchips--vital components in Moscow's efforts to listen to the sounds of new American submarines.

"We took out the Soviet copy of the Intel Corp. microchip and put in the real thing. It worked perfectly," said Assistant Defense Secretary Richard N. Perle, who cited the detection device as an example of how the Soviets beg, borrow, buy or steal new technology from the West.

Perle is the point man for Reagan administration efforts to toughen controls on exports of Western technology to East bloc nations. U.S. business interests and America's European allies assert the White House has gone too far in limiting sales to the Soviets. Later this month or early in August, the House and Senate are expected to take up the extension of the Export Administration Act, which expires Sept. 30.

A hard-liner on the Soviet Union, Perle is lobbying hard for changes in a version of the bill passed by the House Foreign Affairs Committee. Calling that version "lopsided and insensitive to the security issue," Perle has encouraged a special panel of the House Armed Services Committee to hold its own hearings on the issue.

"There are obviously valid security interests. But the problem for public policy is to strike a balance. That's where I think they House Foreign Affairs Committee members have failed," said Perle.

His view, on borderline cases, leans strongly toward controls. "It is better to wrongly control than to wrongly license," said Perle. "The consequence of failing to license is loss of a sale. In economic terms, of minor consequences. But licensing something that shouldn't have been licensed will have profound consequences for the country's security."

While the Senate bill comes closer to the administration draft, Perle still considers it too weak in protecting American security interests.

"I hope the administration will make it clear it will veto a bad bill" that fails to meet America's security needs, Perle said in an interview in his Pentagon office, which is decorated with carpets and Persian miniatures collected during his world travels while a national security specialist on the staff of Sen. Henry M. Jackson (D-Wash.).

If Congress fails to pass new legislation, it could simply extend the present law, which Perle feels leaves the president with more authority than some of the measures before Congress. Senate sources, however, suggested that is a dangerous gambit for the administration to play.

The law was utilized by Presidents Carter and Reagan in the Soviet grain embargo and the controversial attempt to keep American companies and their subsidiaries from supplying gear for the Soviet natural gas pipeline.

But its use angered both American businesses, who complained that embargoes cost them sales without advancing United States interests, and Western European allies, who objected to the extraterritorial reach of the administration proposal.

This debate was mirrored in sharp divisions within the administration, with Perle and Assistant Commerce Secretary Lawrence J. Brady taking a hard-line approach and Commerce Undersecretary Lionel H. Olmer urging greater flexibility.

Both Perle and Olmer have testified in favor of the administration's approach, but clear differences show up in conversations with the two. Olmer defends the Commerce Department's control of licensing efforts and its enforcement of export curbs while Perle calls for a greater Department of Defense role in licensing and a separate, police-oriented enforcement detail.

Selling Western technology to the Soviets "is more profitable and less dangerous than smuggling heroin," he said. "If you get on a plane with a suitcase full of electronics, the likelihood of getting caught is small."

Perle said the Soviets devote a great deal of attention to American technology, down to knowing what scientists in American centers of advanced technology do the most innovative work.

Now, he said, Moscow is focusing on microelectronics where a fast-changing technology affects hundreds of weapons systems. That is the basis of the "smart weapons," which can sense their position and the position of the targets on a battlefield. "That ability," Perle said, "spells the difference between success and failure on the battlefield."

In Afghanistan, for instance, Soviet armored personnel carriers are generally conceded to be superior to anything in the American arsenal. But these cars lack the sophisticated electronics of the American equivalents, which if added to the Soviet equipment would be "devastating from our point of view."