6E5G TUNING INDICATOR OR MAGIC EYE, 1935

The designers of the first 'Magic Eye' registered their first electron-ray tube, the 6E5, on June 27, 1935. This tube initially appeared in RCAs' console-model product line that same year. RCA was fearing a loss of market share to competitors' new lines of very small and midget radios, many of which were designed and produced in Los Angeles. RCA's promotion touted the "Magic Eye" as an elegant feature of their upper product line - where profit margins were greatest.
Not surprisingly, the 6E5 wouldn't fit inside the competitors' smallest sets. The name "Magic Eye" quickly gained acceptance with the public as the standard identity for the electron ray tube and tuning eye feature in consumer radio sets, regardless of manufacturer.
The tube shown has a concave disc inside that is illuminated on the sides of the bottom edge as the signal is increased the two illuminated edges move towards each other in an arc until they touch at full signal.

A1325