TUBE, PHOTO EYE RECEIVER, 4 PIN BASE, RCA 918

RCA 918, an early gas-filled phototube with a semicylindrical photocathode surrounding a central anode. The electrical characteristics of the 918 are extremely similar to those of the more common RCA 930 / 1P40 phototube, but the elongated envelope of the 918 accommodates a photocathode which is nearly double the size of the 930 photocathode. The 918 haS a S-1 spectral response and a peak sensitivity of 800nm.