Basic Construction

The green glow you see on a electron-ray tube is produced when electrons emitted by the cathode strike the "Target" (anode or plate) which is coated with the fluorescent mineral willemite.

Chemically, willemite is known as zinc orthosilicate: Zn₂SiO₄.

Worldwide, willemite is a relatively rare mineral. As luck would have it however, economically significant deposits exist at the Franklin and Sterling Hill mines in New Jersey. This proximity to Dr. Du Mont’s lab no doubt influenced his use of the mineral. Had other members of the fluorescent mineral family been used, the glow of tuning-eyes (as well as early cathode-ray tubes) could have come in shades of yellow, blue, or red. Eventually, electron-ray tubes were produced using a manufactured chemical equivalent to willemite - the same "P1" material used in oscilloscope tubes.

Basic Elements of RCA's 6E5

Electron-ray tubes described in this article are dual-section tubes. In addition to the electron-ray indicator elements (cathode, ray-control electrode, and target), there is also an internal triode which operates as a d-c amplifier. This triode is necessary, either internally or externally, to develop and control the voltage levels necessary for the ray-control electrode to operate properly. In these dual-element electron-ray tubes, the plate of the triode is internally connected to the ray-control electrode. How this operates is described in the Circuitry section of this article.