Need an elliptical wave-guide transmission-line system? Looking for a machine that automatically "writes" your signature on fund-raising appeal letters?

How about a new Bible game program for children, guaranteed to attract youthful TV viewers and make them better Christians?

These items are among the most eclectic assortment of goods and services seen at any convention in Washington. All have been on display here this week at the annual gathering of the National Religious Broadcasters, which closed yesterday.

The 227 exhibits crowded into the display area of the Sheraton Washington included the usual assortment of hardware and software essential to a broadcasting operation.

But there also were many unconventional exhibitors taking advantage of the assembly of 4,000 men and women committed to a fundamentalist/conservative brand of Protestant Christianity.

The Lord's Airline, for example, offered promises of "Christian music, scripture and Bible stories," and "behind every seat, a plaque of the Ten Commandments" for Christian travelers.

If it ever gets off the ground, the Lord's Airline will provide more than just transportation. According to the modest promotional material provided at the booth, which was not always staffed, it will offer airline employes -- Christians, of course -- the opportunity to take part in the ultimate battle against Satan as part of "the Lord's air force."

"For the first time since the creation of the world, The Lord's Airline will . . . actually trespass and invade his territory." Satan, the airline promoters asserted, will react and "will continually attack us with his fiery missiles . . . We need your continuous prayers for this colossal undertaking."

Though most of the visiting broadcasters appeared reasonably trim, a Massachusetts organization offered "Fit for the Kingdom," described as "a Christian group diet program that is sweeping the country."

"We just took the American Dietetic Association diet and added Christian motivation to it," said Mary Haig, standing behind the tray of plastic models of cheese, steak, broccoli and other foods. She said 200,000 people across the country have used the program, and handed out a color folder with a picture of Miriam Everts, who joined the program at age 81 and lost 102 pounds. Nothing else was disclosed about the smiling, white-haired woman.

The exhibitors were assigned space with little regard for compatability. Rabbi Yechiel Eckstein and his Holyland Fellowship of Christians and Jews, a Chicago-based organization trying to promote better understanding between Jews and fundamentalist Protestants, admitted being faintly uncomfortable next to a supplier of rather aggressively evangelistic T-shirts.

But it could have been worse. Some of the literature handed out by other exhibitors was unmistakably anti-Semitic.

There was a Christian Dating Service from South Orange, N.J.: " . . . direct and honest, eliminating all pretense . . . . Send $5 for your info/application packet."

A Christian employment counselor, Intermatch, from Seattle, offered an information link between organizations needing Christian workers and "Christians seeking places of service." The fee: $35.

A CBS camera crew and reporter Morley Safer created mixed reactions as they roamed the exhibit area, stopping for random interviews for a forthcoming "60 Minutes" TV show.

"Some of us are trying to hide and some are polishing all their buttons" in anticipation of a few seconds on camera, said one exhibitor, firmly in the first category. "Usually, the ones that are polishing their buttons are the ones we wish would hide."