Eugene Rietzke came to Washington from the west coast in 1924 with a mission: The Navy wanted him to teach radiomen at the Naval Research Laboratory about triode vacuum tubes.

Triode vacuum tubes, the big technological breakthrough of the early 1900s, were the building block for modern radio and television communication, and Rietzke was one of the few men in the country who knew anything about them.

"I started teaching vacuum theory before the book was written. Then I decided to write the book," said Rietzke, who is now 80 and living on a 20-acre McLean estate with his wife, Lillie Lou.

The book, the correspondence course called Capitol Radio Engineering Institute, came out in 1927 and was the first to offer advanced electronics to professionals. It was so successful that Rietzke resigned a year later from the Navy he had served since World War I and ran CREI full-time.

By 1932 Rietzke had expanded CREI into a proprietary school in Silver Spring. In 1964 he gave the school to a nonprofit board of trustees and it became the Capitol Institute of Technology. Now located in Kensington, it is one of 43 accredited schools in the country offering a bachelor of science degree in engineering technology.

Where Rietzke's CREI (which still exists as part of McGraw-Hill) started with vacuum tube theory in 1927, his CIT is now teaching young men and women about computers, lasers, radar, fiber optics, micro processors and solar energy.

For his pioneering work in electronic engineering education, Rietzke was awarded the DeForest Audion Award in February. The DeForest, named for the inventor of triode vacuum tubes, is the Oscar of electronic engineering.

The school, celebrating its 50th anniversary this year, honored Rietzke with a banquet this week. On Saturday Rietzke will deliver the commencement address at graduation and Acting Gov. Blair Lee III will receive an honorary degree and present opening remarks.

CIT has 300 students, up from 35 in 1932. They come from Ethiopia, Nigeria, Kenya and Iran as well as Silver Spring and Clarksville, Md. There is a four-year program leading to an associate of arts in technology degree; and a one-year program leading to a special state of Maryland certificate for electronic technicians.

In an ear of high unemployment and rigid hiring ceilings, CIT enjoys a 95 per cent placement record. In 1974, 22 per cent of the graduates of the four-year program went on to graduate school; all but five of the remaining graduates found jobs in industry or government.

According to Bill Troxler, dean of instruction, "If I had three times the graduates I could find them all jobs. It's an employee's market. We don't bother having the employee's market. We don't bother having the employers come out and interview. They give us a standing order. Sight unseen, they tell us. 'Send me 30 people - we know what your students will be like once they come to us."

Many of CIT's graduates are employed locally by such technologically oriented companies as Westinghouse, Bell Telephone, IBM, General Electric and Singer-Link. They are among the persons designing fiber optic (glass wire) replacements for copper wiring in the Bell Telephone system; they are the men and women repairing and maintaining sophisticated medical devices in area hospitals. As graduates develop new technological expertise on the job they return to school to advise the faculty on developing new courses.

"In almost any industry you can think of, electronics have a place - entertainment, communications, medicine, space," said Gen. Harold P. Johnson, acting president of CIT. "Electronics is 40 per cent of the gross national product. Most schools for engineers are high on math and theory but low on application. We take things from the other end - we teach application with theory so our students can go out and do a job."

CIT graduates of the four-year program are engineer technologists. "They work side by side with engineers who have graduated from such schools as MIT and Cal Tech," explained Johnson, "but they are not pure scientists; they work with known theories and functions and combine them to provide new functions. They repair, maintain and design technological equipment."

With the increasingly varied uses of computers and with electronic technology changing rapidly, one problem the school faces is keeping current.

Curriculum changes are usually in the form of additions. "The trouble with this business," said Rietzke, who is still an active board member, "is that you can't stop anything. You have to teach vacuum tubes - they're still part of theory."