Anatoly Shcharansky led 300,000 people in song yesterday and recalled his nine years in Soviet prisons and labor camps as he urged the gathering not to forget those he left behind.

"Together we have won once," he told the crowd at Solidarity Sunday, an annual rally for Soviet Jews. "Together, we will succeed again."

In his speech, Shcharansky recalled the efforts of Soviet officials "to convince me I am alone."

"But I knew what they only sensed," he said. "That I was not alone, that my wife, my people, you all were with me. They were trying their best to find me a place where I would be isolated . . . but all the resources of a superpower are not enough to isolate a man who hears the voice of freedom, to isolate a Jew who hears the voice of solidarity with his people . . . . "

Shcharansky begged the crowd not to forget 400,000 Jews still in the Soviet Union but trying to emigrate to Israel and asked his audience to press the U.S. government for political and economic sanctions on the Soviet Jews' behalf.

His wife, Avital, expecting their first child, was unable to accompany Shcharansky because of concern for her health. She was a fixture at past Solidarity Sundays, pleading each year for Americans to apply pressure on the Soviet Union to release her husband and other political prisoners.