The VR137 was specified for VHF low power transmitter use and the commercial name is EC52. The anode dissipation is 7 Watts and the full power frequency rating is 300 MHz. The maximum frequency that useful power could be obtained was 400 MHz.
The envelope is clearly able to accommodate a pair of these small electrode systems.
As with all valves produced in the early days of the glass disc base the pins are short and equi-spaced around a circle. The evacuation seal is concealed within a metal spigot that enables the valve to be accurately located within the valve-holder.
The up arrow indicates a valve for the UK Government and the D signifies Mullard's Mitcham factory.
The triode is on the left with heat sink fins on the control grid supports. The twin rods on the right hold the top mica and the getter holder that was fired outwards towards the envelope.
The cathode tube is rectangular. The close pitch grid is wound on copper supports for good heat transfer to the radiators at the top.
The lower mica showing the small metal pieces that spread the load across a wider circle of mica.
The wide glass tube envelope is 32 mm in diameter and, excluding the B9G base pins, is 59 mm tall.
References: Data-sheet, 1040 & 1043. Type VR137 was first introduced in 1946. See also1946 adverts.
