Tuning eye


Tuning eye

A vacuum tube incorporating a cathode ray-incited fluorescent screen on the front of the tube. The tuning eye was used in the late 1930s and early 1940s to provide a visual indication of when a radio was optimally tuned. The tube was mounted in the radio in such a way that the image (a bright, varying width annular sector of the screen) on the tube could be watched while the tuning knob was turned.