The Soviet Union is expected to break its self-imposed isolation from Western satellite technology by signing an unprecedented information exchange agreement with Intelsat, with a commitment to join the international satellite consortium within two years, according to sources involved in the negotiations.

Soviet agreement to do this would be a tacit admission that the Soviet Union's East Bloc competitor to Intelsat -- Intersputnik -- does not meet all of its telecommunications needs.

The sources said the proposed agreement with the Soviets was sent to Moscow last week by Intelsat, the global consortium that provides telephone, telex and TV transmission to most of the world. It is awaiting the signature of V. A. Shamshin, minister of posts and telecommunications of the U.S.S.R.

"No doubt the Soviets would like to get at Intelsat's technology because of their more primitive technology base," said William Schneider Jr., undersecretary of State for security assistance, science and technology.

Intelsat, the International Telecommunications Satellite Organization, is an international satellite services monopoly controlled by its 109 member nations. Although the 21-year-old system was created by the United States, which is the biggest single user, the United States has no legal means to prevent Intelsat from sharing technology with, or granting admission to, the Soviets. The People's Republic of China already belongs to Intelsat.

Despite the lack of legal authority over Intelsat, an administration official who asked not be identified said yesterday that technology-transfer questions will have to be studied by the Defense, Commerce and State departments. "There would be concern over some technology-transfer issues," he said.

The proposed agreement allows the sharing of information about respective satellite systems. At the same time, by signing the agreement, the Soviet Union can start to use the Intelsat system far more extensively for telecommunications and broadcast purposes, sources said. The Soviets also construct a new revenue base by selling satellites and launch vehicles to Western Intelsat members.

The proposed agreement sets the stage for Intelsat to broaden its base of users throughout Eastern Europe as limited competition is introduced to the monopoly by the United States, sources close to the negotiations said.

Ultimately, the Soviets will have full membership in Intelsat, said a source very close to the negotiations. "We did agree the Soviets would have full membership within two years," the source said.

In the future, the two satellite systems could be merged, eliminating costly redundancies, Intelsat said. "I believe there should be a unitary system or it will be too expensive," said Richard Colino, American director general of Intelsat, in which the U.S. holds the largest ownership share. "I really believe encouraging the common membership and operation of a satellite system is important," he said.

So far, the Soviets have used the Intelsat system on a limited basis and never have exchanged technical information with the West. Nor have they allowed the Eastern Bloc countries to use the Intelsat system, except for Yugoslavia, which is a full member of the consortium. Intelsat has not encouraged its members to use the Intersputnik system, either.

Schneider said "it may turn out the Soviets may prefer to use Intelsat to acquire Western technology and may decide not to let private citizens use the technology at all, but would let the military use it solely for military communications, which would perhaps contribute to the strengthening of the Soviet defense establishment."

The Reagan administration will adopt a wait-and-see approach for the time being about the proposed agreement and where it might lead, Schneider said. "It would be interesting to see how it evolves," he commented. There is no security danger in the proposed agreement, because Intelsat is used solely by the United States for commercial purposes. The U.S. military uses its own satellites for classified communications and specially encrypts the signals so they cannot be intercepted, he said.

"We would keep the Soviets out of our technological pants -- the technical know-how would stay with the staff," said one Intelsat source who declined to be identified. There are no technology-transfer questions involved in letting the Soviets use their own earth-based satellite receivers more extensively in tandem with services the Intelsat satellite system provides, he said.

The Soviets long have been attracted to the benefits of modern technology and fearful over the consequences that could threaten tight control over information, experts say.

"The Soviet leadership is beginning to perceive they must move ahead with telecommunications, which creates political difficulties," said Joseph N. Pelton, director of strategic policy for Intelsat. "But not moving ahead creates economic difficulty."

The proposed agreement, drawn up after Intelsat's Colino visited Moscow at the end of February, gives the Soviet Union the ability to become the largest TV broadcaster in the world and could further their propaganda goals, said Intelsat's Pelton.

"The Soviets are not dumb, and their ability to reach the Third World effectively would be of enormous strategic importance -- they would enjoy the irony of an Intelsat weakened by competition," he said.

The State Department's Schneider said TV broadcasting is not a threat to the Western World. "This [agreement] would not facilitate direct [TV] broadcasting by us into the U.S.S.R. or by them into the USA" because of technical considerations, he said. Nor are many Western countries, which already have access to Soviet satellite signals, anxious to receive Soviet TV programming, he added.

David J. Markey, assistant secretary for communications and information at the Commerce Department, said the proposed agreement only strengthens the Intelsat system by building on its membership base. "It shows again the Intelsat technology is the best in the world," he said. "All this stuff about the Soviets taking over if Intelsat gets competition is a red herring."