Opponents of a Carter administration plan to sell seven super-sophisticated flying radar systems to Iran told a Senate committee yesterday the sale would risk the loss of a major edge in air technology to the Soviet Union, and might involve American technicians in an Iranian war.

John Culver (D-Iowa) and Thomas Eagleton (D-Mo.), leaders of a Senate move to block the sale, also laid the groundwork for making the issue a first test of the arms control policy Carter enunciated in May.

Culver and Eagleton appeared before the Senate Foreign Relations Committee to urge adoption of a resolution they and 14 other senators have filed to prohibit the $1.2 billion sale of seven Airbourne Warning and Control Systems (AWACS) to Iran.

"If we believe the glowing praise the Air Force showers upon AWACS' look-down radar and advanced equipment," Eagleton testified, "logic dictates our taking a skeptical look at the proposal to transfer this technology to a semi-literate country which does not have the resources to absorb it."

Meanwhile, administration sources said a still-classified letter from director of the Central Intelligence Agency, Adm. Stansfield Turner, expressing serious reservations about the sale on security grounds was based on faulty information about the version of AWACS contemplated for Iran.

Coding equipment in the U.S. Air Force AWACS will not be installed in any Iran AWACS, the sources said.

Other sources said, however, that AWACS would be useless to Iran without some kind of "secure communications" whether or not it was the exact piece of equipment used on the U.S. version.

"Their words could be widely heard from 29,000 feet" without advanced coding equipment, the source said. "You wouldn't want anyone to hear you saying, 'There's an enemy fighter right behind you.'"

Iranian officials had no comment on the report that the planes they would receive might differ from the ones the United States will deploy for itself.

Administration sources said that Iran has received sensitive equipment such as the F-4 and F-14 fighter planes without security breaches, and that the feared technology loss could occur with any NATO ally as easily as with Iran.

Eagleton and Culver, however, envision a hostile nation acquiring an AWACS, which is essentially a modified Boeing 707 jet topped by a plate-shaped housing built by Westinghouse and containing elaborate radar, communications, and jamming equipment.

In a shouting, arm-waving performance, Culver said the Soviet Union now equals U.S. technology in most fighter and bomber aircraft, and said sale of the AWACS to Iran could compromise the West's technical edge in air radar.

"Technological achievements such as the AWACS help the United States to offset numerical deficiencies in weaponry," Culver told the subcommittee. "If a single crewman hijacks a plane or sells secrets to Soviet agents, the U.S.S.R. could reap an intelligence bonanza which may endanger our own Air Force and the defense of Western Europe."

The American technicians who would be needed to operate AWACS in Iran - estimated at about 400 in a General Accounting Office report that concluded the sale was not justified - also were cited as an argument against the proposed sale.

Eagleton said more than $30,000 U.S. nationals are now in Iran and the number could rise to 50,000 in three years with AWACS and other proposed sales.

In the event of a war in Iran, he said, "President Carter - or his successor - would face a disturbing policy decision: either to allow Americans to fight a foreign war, or to withdraw them, thereby assuring the defeat of an ally."

Eagleton and Culver also said the sale would violate Carter's announced intention not to introduce new military technologies abroad.

"It makes little sense to turn around, before the ink on that piece of paper is dry, and a few moments later exempt Iran from these guidelines," said Culver.

If Congress is to block the sale, proposals introduced in both Senate and House must be passed by Aug. 5.

The Senate subcommittee appeared impressed by the Eagleton-Culver presentation. "If the administration cannot answer these charges, cannot refute, then there is no ground for even considering this sale," said Chairman Hubert H. Humphrey (D-Minn.)

Administration officials will present their case on Friday. House hearings are scheduled today and Thursday.