The NT36 is a British Royal Navy transmitting valve. In its civilian designation it is the DA100 audio triode. Used as an audio power amplifier it affectionately became known as a 'talkie' valve because of its widespread use in cinema sound systems. The DA100 was also used in the modulator chain of the Marconi SWB8 and SWB10 transmitters.
The DA100 has molybdenum electrodes and an oxide-coated filament.
The operating figures given are for a pair in Class AB1 operation. The output to a 4,000 Ohm load is 175 W at 5% total distortion. In Class AB2 service the output is 300 W at 6% total distortion.
The end of the envelope shows the grid in the rectangular anode cavity.
The detail photo shows the grid and the four filament supports.
This valve came complete with its original wooden crate.
The classic envelope is 85 mm in diameter and, excluding the L4 base pins, is 227 mm tall.
References: Data-sheet & 1043. Type NT36 was first introduced in 1933.