Maker's Name: 
Amalgamated Wireless Australia
Where made: 
circa 1920
10.5 × 2.5 × 1.9 cm

A very early wireless valve made in Australia. Note that the padding material in the box is wool.

It is a triode, with twin tungsten filaments, and coaxial elements. It is a so-called 'soft' valve, referring to the soft vacuum inside.

Secondary emission due to ion bombardment of the cathode enhanced the current in the valve, but made the operation unpredictable.

It has bakelite button endcaps, but flying leads rather than pins as used in later valves.

Such valves were used in early mitlitary wireless receivers.