The CV789 is based on the 3C24 small American transmitting triode. Despite its small size it produces a considerable amount of RF power up to the low VHF region, 100 Watts with 2kV on the anode.
The anode sheet has been formed into deep corrugations before being folded into a cylinder. This ensures good heat radiation. The grid is made in the form of a cage with the wires crossing at the top to close the end. The filament is helical.
The grid is connected to the side terminal and the form of the grid cage and filament is shown.
A closer view.
The wide glass tube envelope is 32 mm in diameter and, excluding the UX4 base pins, is 95 mm tall.
References: Datasheet. Type CV789 was first introduced in 1945.