Adolph Dubs, slain yesterday in Kabul, was a broad-shouldered, athletic 58-year-old career diplomat. He had been eager to take on a tough new assignment when he was sworn in as the new U.S. ambassador to Afghanistan last July.

"He went to Afghanistan with great anticipation. He was restless. He was eager to get into the field again. He knew it was a tough post," Marshall D. Shulman, special adviser to the Secretary of State on Soviet affairs, said yesterday. Shulman, a former Harvard and Columbia University professor, had been Dubs' teacher and colleague.

A State Department official since 1950, the Chicago-born Dubs, known by his college nickname as Spike, had been a specialist in Soviet affairs during much of his diplomatic career. State Department officials described him yesterday as calm under duress and moderate in his views on U.S.-Soviet relations.

"He was very clear-eyed, very hardheaded about realities with the Soviet Union, but also a positivist in seeking better relations with the Soviets," a State Department colleague remarked yesterday. His Kabul assignment was described as a natural outgrowth of a series of posts that kept him in touch with the Soviet Union and neighboring countries, including Afghanistan.

Despite his solid grounding and thorough knowledge of Soviet, Near Eastern and South Asian affairs, some friends and officials said they remembered him best as an affable, down-to-earth, vigorous man who loved sports and was widely thought to have abandoned a possible career as a professional golfer when he joined the State Department.

Even during a recent tour at the U.S. Embassy in Moscow, when he was already in his 50s, one colleague remarked that Dubs "could whip just about anybody at Ping-Pong."

Before going to Afghanistan, Dubs held several influential State Department positions. In 1974, he was named deputy assistant secretary of state for Near Eastern and South Asian affairs. Previously he was deputy chief of mission at the U.S. Embassy in Moscow and he became charge d'affaires -- in effect, the acting ambassador -- for of former ambassador Jacob D. Beam.

Shulman described Dubs' Moscow tour as "a year of turbulent events," which he said "Spike managed with unflappable good humor." It was a time of Nixon administration moves to improve U.S.-Soviet relations that was marked by strains over the ending of the Vietnam war and the 1973 Middle East conflict.

Dubs received a B.A. degree from Beloit College in Wisconsin in 1942 and later studied at George Washington University, the Foreign Service Istitute, the National War College and Harvard University. He served in the Navy as a lieutenant during World War II.

His State Department duties also took him to West Germany, Liberia, Canada and Yugoslavia.

His second wife, the former Mary Ann Parsons, an editor of the Congressional Record, was in Washington at the time of his death. He is also survived by a daughter, Lindsay Jane. Memorial services have been scheduled for 10 a.m. Tuesday at Arlington Cemetery. An Air Force plane is scheduled to bring back his body Sunday.