The arturus brand is the one most associated with blue envelope glass. This exhibit is an indirectly heated triode. The type 56 identification is etched into the envelope dome and only visible under oblique lighting.

The anode is notched and stitched. The control grid can be seen at the right of the image.

The balloon envelope is 38 mm in diameter, and excluding the UX5 base pins is 87 mm tall.

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This exhibit was last updated on 30 March 2008