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 control grid with cooling fin. Only one side of the envelope is used for the triode.
The Cathode is flat through the anode and the grid is close wound as can be seen both from the few turns of wire visible and the spacing of notches on the copper support rods.
The wide glass tube envelope is 32 mm in diameter and, excluding the B9G base pins, is 59 mm tall.
References: Datasheet, 1040 & 1043. Type VR137 was first introduced in 1946.