The classic 807 beam tetrode valve is unusual in still being designated as current production in the 1960s and having a five pin base.
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.
These valves were much used in medium power amateur radio transmitters for high level modulation. In this use the output transformer, called a modulation transformer, would be impedance matched to the anode circuit of the RF power valve. The audio power would increase or decrease the amplitude of the RF envelope.
The 807 was also a workhorse of the HF bands. As a transmitter power amplifier (shown in the lower table) operating in class C producing 40 Watts of RF, it would need a pair of 807's in push pull to generate the 20 Watts of audio required to fully modulate the valve. Other modulation systems operating on the screen grid would require much less audio drive but with less RF output.
The classic envelope has a maximum diameter of 47 mm and a length, excluding the UX5 base pins, to the tip of the top cap of 128 mm.
References: Data-sheet, Data & 1040. Type 807 was first introduced in 1938. See also 1938 adverts.