The KL35 is a post WWII battery audio output pentode valve.
The anode load for use in single ended circuits is 19,000 Ohms.
The bright anode is oval at the ends and flat across the main width. The evacuation hole in the pinch is clearly visible.
The end view of the anode. The top micas fit tightly into the shaped top of the envelope to give mechanical rigidity. Above the first mica can be seen the cooling fins attached to the anode support rods.
The view through the envelope dome. The opening in the top mica reveals the wire grids. The springs of the filament supports do not reach the centre of the grids, instead the oxide coated filament rests on the side of the gap in the mica. The single strand filament passes through the grids four times and forms a pair of inverted V's.
The classic envelope is 40 mm in diameter and, excluding the IO base pins, is 88 mm tall.
References: Data-sheet & 4065. Type KL35 was first introduced in 1946.