The S4V is an indirectly heated screened tetrode from 1929. This exhibit is from later production and is fitted with a B5 base. The anode is taken to the top cap. The S4V was designed as a screen grid class A RF amplifier as the front end of a radio receiver.
The gettering obscures most of the electrodes. The form of construction can be seen clearly in the PM12.
The anode is a flat plate either side of the large cage screen grid. The control grid supports are visible in the middle of the image.
One anode plate with grid wires behind.
In this image can just be seen the glass bead that holds the anode supports. The both anode plates connect to the top cap. The insulated support wires are attached to the screening ring above the pinch. Seen here on the right.
In this image, courtesy museumvictoria.com in Australia, can be seen the box that is the screen grid and the small anode plate. Two anode plates exist - one either side of the screen grid.
The balloon envelope is 46 mm in diameter and, excluding the B5 base pins, is 112 mm tall.
References: Datasheet, 1043 & hupse.eu/radio/tubes/s4vb.htm. Type S4V was first introduced in 1929.