This air cooled triode has a copper anode as part of the envelope construction.
The box that houses the valve is clearly marked Station 2RN Dublin 1926 on its upper surface. This makes this an early example of the external anode transmitting valve.
The base pins are quite short and different to valves such as the ACT9 from GEC.
Inside the glass envelope can be seen not only the electrodes but also a mesh screen.
The wide glass tube envelope is 68 mm in diameter and, excluding the base pins, is 443 mm tall. The cooling fins are 133 mm diameter and 153 mm long.
Updated March 01, 2013. shape:wide.glass.tube construction:pinch type:triode age:1920.1930 base: pin: