This exhibit is a teaching aid and the information we have comes from writing on the packaging - the original instruction sheet is missing. It is a bright emitter and is designed to be used with an HT of up to 500 Volts and a grid bias from minus ten to plus ten volts. The maximum current is given as 5.0 mA.
The electrodes are mounted parallel to one another. The filament is a zig-zag of tungsten wire, the grid is a disc with wires stretched across it and the anode is a plain disc. All of the discs have the ends folded over for rigidity. The anode connects to a top pin and the grid to a side pin.
The planar nature of the electrode arrangement.
The support wires pass into glass tubes before they reach the outer 120mm diameter glass envelope.
The filament connections are 4mm sockets on the base.
The cap on the left is a cover for the evacuation pip.
A μ-Tracer plot of the characteristic curves for this exhibit.
The balloon envelope is 40 mm in diameter, and including the base is 290 mm tall.