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This R Type exhibit was made by Radions and is phosphorus gettered. Like the Moorhead version the electrodes are mounted vertically.

The single strand filament has broken. The tension spring has retracted and the broken end is at approximately 45° across the grid.

The grid is slightly displaced to the side.

Processed to monochrome for a clear view of the electrodes.

The etched lettering on the bulb is difficult to see. The text is Radion Valve.

Another view of the etched lettering.

On the other side the words Patent Applied For are etched into the glass.

The third style of BBC stamp. This dates the valve to between July 1924 and the end of 1927.

The balloon envelope is 53 mm in diameter, and excluding the B4 base pins, is 93 mm tall.

References: ¹⁰⁰⁵, ¹⁰⁰³ & ¹⁰⁰⁴. Type R Type was first introduced in 1916. See also 1916 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶