April 6, 1984

In a move to encourage employees of the Shell Oil Company to sell a crucial block of stock they hold, the Royal Dutch/Shell Group is offering to buy their holdings at an estimated $66 a share - $8 more than is being offered to other Shell stockholders, papers filed with the Securities and Exchange Commission showed yesterday. The proposal, in which Federal income taxes would be partly offset, is being offered to 28,000 employees, including top executives, and will cost Royal Dutch nearly $200 million. Acting over the objections of the company, of which it already owns nearly 70 percent, Royal Dutch is offering to pay all of Shell's stockholders $58 a share, or $5.5 billion in cash, to get the rest. The new provision for Shell employees would raise the overall cost to $5.7 billion.

Stripped to its Baroque bones by copper-hungry vandals and left behind by rescue plans that always fell apart, the old Police Headquarters - still looming over the low roofs of Little Italy - is now to be an apartment house. ''After being vacant for 10 long years, 240 Centre Street is about to start a new life,'' Mayor Koch said yesterday, announcing the sale of a building whose address was once synonymous with the police. ''This will be a restoration, not a renovation,'' one of the purchasers, Arthur D. Emil, said. ''We will do detailing as close to the original as possible.''

The Justice Department today charged a Swedish electronics company with illegally exporting American parts and equipment to the Soviet Union that gave the Russians advanced military radar capability. The department said Datasaab Contracting A.B., based in Jarfalla, Sweden, violated the terms of an export license it was granted by the Commerce Department in November 1977. The license included 10 restrictions designed to permit the company to sell only equipment with the capability of a secondary air traffic control system, able to track civilian aircraft for air safety purposes. But the Justice Department said the Swedish company ''knowingly violated'' those restrictions and between 1977 and 1980 shipped to the Soviet Union United States parts and technology from other Western countries that increased the capability of the system and ''gave the Soviet Union technology directly applicable to military research and development efforts.''

FRIDAY, APRIL 6, 1984 Markets Major banks raised the prime lending rate half a point, to 12 percent. The increase, the second in three weeks, brought the key interest rate to its highest level since October 1982, just before the recession ended. Most economists predicted that the prime rate would climb further but insisted that the economy was not yet endangered by rising interest rates. (Page A1.) Stock prices tumbled in heavy trading after the prime rate increase was announced. The Dow Jones industrial average slumped 18.01 points, to 1,130.55, its lowest close in nearly a year. (D1.)

The space shuttle Challenger is set to embark on an ambitious mission to restore an ailing satellite to health and thus demonstrate for the first time the ability of astronauts to make orbital service calls to extend the useful lifetime of space facilities. Liftoff is scheduled for 8:58 A.M. Friday, barring any last-minute problems with the spaceship or the weather. Clear skies are forecast, though there is some concern about the stiff high-altitude winds. The five-man crew plans to rendezvous with the wobbling, rolling satellite, Solar Max, capture it and bring it aboard to replace its malfunctioning systems. This is to involve two space walks, after which the satellite, if the repairs succeed, will be redeployed to resume its observations of the sun's turbulent behavior.