The TZ40 is a magnificent audio triode that was designed for high power audio use in class B. A pair would deliver 175 Watts at 5% distortion.
The signal input would be 220 Volts peak to peak between the two grids. The anode load would be 7,000 Ohms.
It is quite possible that the main use for this device would have been modulators for small AM transmitters. The data-sheet is for the very similar DA41.
The TZ40 was a development of the earlier T40, also with a 40 Watt anode dissipation but with a gain of 25 whereas the TZ40 has a gain of 62.
The base has the old UK military stores code of 110E/37.
The Hytron name on the base together with Made in USA.
The Crown and AM of the UK Air Ministry.
The Filament tension springs and ceramic insulators for high voltage insulation.
The grid pitch is indicated by the notches on the grid supports.
The graphite anode showing the thickness of the material.
The balloon envelope is 51 mm in diameter and, excluding the UX4 base pins, is 148 mm tall.
