The 815 is a power double beam tetrode based on the American pattern of two separate valve sections. Operation can be as a push-pull modulator (Class AB2) or RF power amplifier. The 815 produces maximum power up to 125 MHz and at reduced ratings can operate to 175 MHz.
The RCA logo. The black rectangular box anodes connect to the top caps.
One anode seen full face. The supports are fixed at the sides.
The two sections have no internal neutralisation and that has to be provided externally.
The top mica components. The cathode tube is flat across the width and has rounded ends. The control grid heat sinks both bow inwards towards one another. The beam plates are bridged below the anode connections. The screen grids are connected by a bright vertical tape. This is on the right side of the image.
The wide glass tube envelope is 51 mm in diameter, and excluding the IO base pins is 98 mm tall.