The CV1135 is a power triode based on the M-OV E1148 experimental valve that became the DET20. It is also known as the VR135 and the NR80.
The triode is mounted high up in the envelope to allow short and thus low inductance connections to the two top caps, one for anode and the other for the grid.
A closer look at the triode electrodes. The control grid is close wound on copper supports.
The wide glass tube envelope is 30 mm in diameter, and excluding the IO base pins is 73 mm tall.