History: Tuning Eye Beginnings

"Tuning Eye" is the common name applied to the green-glow tubes used in radio equipment to visually assist the listener in tuning a radio station to the point of greatest signal strength. Officially called "Electron-Ray" tubes, they are so named to distinguish them from the cathode-ray tubes used to produce images in television, though the two types share a common ancestry and fundamental architecture.

The electron-ray tube was invented by Dr. Allen Du Mont in 1930 as a result of his related work to develop cathode-ray tubes for television. Dr. Du Mont had just completed the transition from his engineering job with Westinghouse to become Chief Engineer for the De Forest Radio Company in Passaic, New Jersey. Dr. Du Mont most likely used the lab in the basement of his Upper Montclair home to carry out his experiments since he, and not the De Forest Radio Company, owned the patent for the electron-ray tube he created. The patent was sold by Dr. Du Mont to the RCA in 1932. Prospects at the De Forest Radio Company at the time were not very bright as the company was in severe financial difficulties. The company went into receivership in 1933 with RCA gobbling up most of the assets. The sale of the electron-ray tube patent provided the seed money for Dr. Du Mont to form his own company. Over the next thirty years, the company bearing Dr. Du Mont’s name pioneered early oscilloscopes, television sets, television broadcasting, and prospered greatly during and after the World War II with the development and production of defense electronics.

It would be three years before RCA would bring Dr. Du Mont’s creation to market.