The classic 807 beam tetrode, this example is from Emitron.
The parameters given are for single ended use. When used in a class AB1 as a push pull pair with 600 Volts on the anode an output power of 65 Watts was normal.
The high voltages on the anode make ceramic insulators a wise precaution.
One characteristic of most 807's is the curved lower screen. In this example a plain rectangular box screen has been used.
The classic envelope is 50 mm in diameter, and excluding the UX5 base pins is 132 mm tall.
References: Datasheet & 1040. Type 807 was first introduced in 1938.