The Bell Helicopter complex is at Isfahan, its modern office hidden deep in the city in an unmarked cement building close by the local Pepsi plant. The Bell people were not happy to find a reporter at the door.

Are you really an American? They asked. A credential? Well, we can't talk here: Phones are tapped, there are microphones in the walls. Could we go for a drive?

In the car, the boyist brown-haired 35-year-old man was saying, "You never know. Here if you talk about something they don't like, you're out, 24 hours later, you're out - with no time to sell your household goods, your car, your other possessions. And you never know what they are going to regard as being harmful to their security? They change their minds every minute."

Suddenly his small car stopped short; we had almost collided with a jitney cab. "Can you imagine giving a constitution to this bunch of monkeys?" he asked rhetorically.

For America, Iran has become big business. Non-oil U.S.-Iranian trade rose from $400 million in 1972 to more than $2 billion in 1976, quintupled. Iranian-American arms deals have totaled $15 billion over the past six years, including expensive U.S. support-service contracts. Each year, the American presence has grown. There are now 31.000 American in Iran.

Yet passing money has not made Iranians and Americans friends. "The conclusion is inescapable that Iran's industrialization, so drastic and so sudden, is being supported by Americans on high salary with no interest in the country and an active dislike of its people," said a former AID official at the State Department.

"You are not really travelers," said a young Tehran painter. "You are tourists. A traveler is interested in what is done differently from his own country You Americans resent everything that is not exactly the same as what you have at home."

"Our ambition is to make as much of America out here as we can," said the wife of a Bell technician at Isfahan. "We owe it to our children."

The American stationed in Iran rarely make any attempt to eat the native food. They buy their goods at reduced prices at the PX, their housing is subsidized, they live apart from the natives. They have their own schools, and their socializing is done together. "They make it insultingly plain that they are used to better at home," said a Pakistani diplomats wife.

The Defense Department forbids Americans to consume local dairy products, claiming that they do not satisfy U.S. pasteurization standards Special flights of C-130s bring in tons of milk, eggs and butter of "acceptable quality."

The insult is not lost on their hosts."We eat them, the whole country eats them, and we are not sick," a Tehran schoolgirl said.

An American businessman and his wife were booked by their Iranian hosts at the Park Hotel, considered by most European visitors to be the most gracious in Tehran. The couple left because they "stay only in deluxe hotels and calling the Park deluxe is really stretching the word a bit."

They switched to the Hilton, but sitting in the lobby of the American-built hotel full of unconvincing modern copies of Persian furnishings, they complained that the furniture looked as if it had not been changed in 10 years.

"A main bond of association for Americans abroad is to run down the country they're in," said an American woman, divorced from an Iranian who works for the Ministry of Science.

Shortages, high prices, the crooked character of Persians, attempts to cheat them - these are constant themes of private American conversations. Such talk helps create an impression among the Americans that they are encircled by hostile forces, and they make little or no effort to break the circle by taking an interest in the local culture.

"Most of you do not do us the courtesy of knowing our language, although we know yours," an Iranian engineer said.

Most Americans know nothing of Islam, either. The result is that they often see something sinister where there is only something different.

An American woman wrote of houses in Iran being surrounded by walls; she felt it spooky, not knowing that walls around houses were built for the seclusion of woman, a requirement of Islam. A man who worked four years in Iran for the State Department remarked that Persian men seemed to shave only when they had to, that most displayed a spiky, heavy growth of three or four days. "A little beard is pleasing to Allah," was the reply. What he had thought was unpemptness was in fact religious observance.

Bell, like many American defense contractors in Iran, is involved in training, maintenance and support for the Iranian military. The shah's helicopter force is second only to the U.S. inventory. He has 500 military Bell helicopters, plus another 100 Augusta Bell models.

Since Iran's shortage of skilled labor and technical management is acute and chronic, Iran has had to rely on Bell to keep the Iranian helicopter fleet flying.

Bell says its machines are of the latest military type. They need eight to 10 hours of intensive maintenance for every hour of flight. Bell's contingent is the largest American group in Iran, including the military. As of April 1975, Bell had more than 1,700 active employees there and 6,000 dependents. Those numbers increased by 8 per cent last year.

Isfahan, where the 45-acre Bell base is located, is a sizable city 457 miles from Tehran. It is said to contain more blue onion-domed mosques than any other city in Iran. To make the overseas assignment attractive, the home company offered financial enticements: tripled salaries and boosts in position. There were also tax breaks that amounted to a federal subsidy.

Bell told its people Iran was a hardship post and tried, largely in vain, to discourage families from going along. But for the normal two-year assignment, the rewards looked big, and many took the bait. A Bell personnel official described the community his company brought:

"What you have here are ex-military professionals, the guys who liked Saigon, the mid-level fellows who don't know any other way of making a living. The money's good, so they came."

Said a friend of his, "I don't know why we seem to have chosen to recruit so many of our people from the jails of Texas and Tennessee."

It's a rough, tough, knock-'em-back, country-music, Coors beer-drinking crowd. They are arrested frequently for starting fights, for public drunkenness. They have ridden their motorcycles through the great Shah Mosque, one of the most sacred Moslem shrines in the city, the equivalent of "playing your transistor during an audience with Pope Paul," said an American secretary.

At the base one night, a pilot, married to a German girl, beat her up. That night she slit his throat. A language instructor for a Bell subcontractor summed it up: "Most are out of their depth. They're poor white trash here for only one reason: to make beaucoup bucks."

The psychological stresses of isolation, of inedible local food, of not knowing the language, the shortage of women - these were bad enough, but the real shock came when the American community realized that the shah was going to run a strict shop. To leave the country Bell employees need exit visas that must be approved by the government every three months.

"The way to become paranoid is to hang around us a while," said an instructor for Telemedia, a Bell subcontractor.

Upon arrival, Bell employees are instructed never to refer to the shah by name in public nor to mention the Empress Farah Diba, except in code. One overheard criticism and a Bell employee could find himself on a plane, with most of his personal possessions confiscated. So, among the Americans of Isfahan, the shah - King of Kings and Light of the Aryans - is referred to as "Fred," "Clark Kent" and "Pepe." As a couple, the emperor and empress are called "Ken and Barbie" or "George and Martha."

Iranian security at the base is strict, and punishment for violations swift. A man took a photo of an F-14; he was gone. Another was found walking in a restricted area; he was shipped home. Another was expelled from the country for lacking proper identification while on the base.

"There is literally nothing to do," said a Bell English teacher. Leisure means beers at a local hotel bar, griping, playing bridge, seeing a movie now and then.

One night near Christmas, in Isfahan, a big event for the evening was to go up the street to an English language theater showing "Anatomy of a Murder."

"Christ, I've seen the Goddamned thing already 10 times," a Bell technician said. But he went.

Islam keeps the sexes rigidly segregated. "Just getting a spot of leg here can really be awfully difficult," a pilot said. The boys were sending a colleague from Isfahan down to Shiraz to reconnoiter after reports that the Iranian government ran some brothels down there.

Despite the American attitudes toward them, the average Iranians are eager to be liked. They are proud of their civilization: its art, its poetry and its tradition of hospitality. When I indicated a knowledge of certain Persian traditions, a cab-driver refused to let me pay. Even fumbling attempts to speak Farsi are met with delight and assistance. The generosity of the most common, ordinary peasant is embarrasing: You ask for a cigarette, and he tries to press the whole pack upon you "Iranians are only primitive in their knowledge of machines, not people," said a diplomat.

Perhaps the heaviest blow for the Americans fell Oct. 4, when President Ford signed into law new tax rules that cut the amount of foreign-earned income that is exempt form U.S. taxation. The new rules reached back to Jan. 1, 1976, which meant that most Americans abroad owed considerable additional taxes, since their withholding rates had been based on the old levels.

The companies promised to make good the losses, but the change meant complications, company staff cuts, an increase in foreign competition.

"It's suicidal," said the president of a California road-building company in Iran "It'll drive us out, and Japan and West Germany will take over."

For others, it shattered any hopes they might have had. Said one sad-faced, chubby Bell housewife: "I wanted to buy things when I got home: a house, stuff like that, and where could I make make the money I could here? Now all I'm doing is counting the days until I get out. I'm never coming back."