The EL35 is a larger more powerful audio pentode than the small receiver types and was intended for use in class AB. The EL35 was used for audio amplifiers and modulators for small Amplitude Modulated transmitters. As a single ended audio stage the valve would deliver 6 Watts and in push pull a pair would form an amplifier capable of generating 21 Watts in class AB. The design dates to the early 1940's.
This is another EL35 but with less internal shielding allowing the electrodes to be seen.
The central cathode has three inverted V's of insulated heater inside. The control grid is wound on copper supports and topped off with heat sink fins. The top mica has its fingers bent down showing the interferance fit into the envelope bulb.
The classic envelope is 41 mm in diameter, and excluding the IO base pins is 105 mm tall.
References: Datasheet, 1040 & 1043. Type EL35 was first introduced in 1945.