Yuri Orlov, one of the Soviet Union's leading human right activists, was sentenced to seven years in prison and five years internal exile here yesterday as a courtroom packed by handpicked government supporters applauded and shouted, "He deserves more!"

Orlov was the first of three Soviet dissidents specifically defended by the Carter administration to be tried in the Kremlin's current crackdown on dissent. The harsh verdict yesterday suggests seemingly calculated Soviet intentions to publicly humiliate the U.S. president.

[In Washington, the State Department denounced the action as a "gross distortion of internationally accepted standards of human rights." The House of Representatives, by a 399-0 vote, passed a resolution calling on the Soviet government to free Orlov.]

Orlov, who had been held in jail for the past 15 months, was given the maximum penalty prescribed under Soviet law after the court found him guilty of distributing "slanderous concoctions, smearing the Soviet state and social order, with the object of weakening Soviet power."

The 53-year-old physicist founded the so-called Helsinki group to monitor Soviet compliance with the human rights provision since the 1975 agreement on European security and cooperation. Documents prepared by the group on Soviet abuses of human rights formed the basis of the prosecution's case against him.

The Soviet Union and 34 other nations, including the United States, signed the agreement in Helsinki in the summer of 1975.

Orlov's wife Irina said her husband stood very quiet," as the sentence was read, "looked at me and smiled." She and Orlov's two sons were the only friendly spectators in the courtroom, although one son, Dimitri, 25, was ejected from the room yesterday after shouting, "Father you are the real winner of the trial!"

As during the previous three days of the trial, supporters of Orlov were outside the courthouse along with Western correspondents and security agents.

Among Orlov supporters was physicist Andrei Sakharov, the Nobel PeacePrize winner, and his wife Yelena. Both were detained by KGB security agents after a shoving match that ensued when the Sakharovs attempted to gain admittance to what was billed as an "open" trial.

As the Sakharovs were loaded into a police vehicle, the physicist shouted "Nobel prize for Orlov!" They were released later in the day and accused by Tass, the government news agency, of "insolent holligan actions."

Three other dissidents were taken away by KGB agents separately after the scuffle. Later in the day the agents picked up two more Orlov friends who had asked to appear in court as defense witnesses.

The Orlov trial suggested that more of the dame can be expected in the forthcoming trial of Alexander Ginzburg, a member of the Helsinki monitoring group and director of a relief fund for political prisoners, and Anatoli Scharansky, a Jewish activist who frequently acted as spokesman for Jews wanting to emigrate to Israel.

Like Orlov, Ginzburg is accused of violating Article 70 of the Soviet criminal code, an omnibus provision dealing with anti-Soviet agitation. Because of a previous conviction. Ginzburg could het up to 10 years in prison.

Scharansky has been accused of treason for alleged connections with the U.S. Central Intelligence Agency, a charge publicly denied by President Carter. The charge of treason is a capital crime.

The Scharansky case is viewed as especially significant since it involves an apparent effort to equate dissent with treason.

Yesterday, for the second straight day, Western journalists trying to drive Mrs. Orlov to a safe place to hear her account of the court proceedings were harrassed by KGB agents.

On Wednesday, five carloads of KGB plainclothesmen chased journalist through Moscow, running red lights to play "bumper tag" in thick traffic. Mrs. Orlov was stripped nude to her bra on Wednesday by three KGB men and three women apparently searching for notes about the trial before she was permitted to leave the courthouse.

Orlov has been held incommunicado for the past 15 months. Mrs. Orlov said now that he has been sentenced, Soviet law gives her the right to spend two hours with her husband.

It was not clear whether the Orlov verdict would be appealed. If Mrs. Orlov files an appeal against the sentence, some Western diplomatic sources suggested that it is conceivable that it might be reduced as a concession to world public opinion. Most observers here do not consider this likely, however.

The sharp crackdown which began 18 months ago is apparently designed to crush organized dissent at home and demonstrate to governments in the West that they cannot interfere in what the Kremlin regards as its "internal affairs."