The TZ40 is a magnificent audio triode that was designed for high power use. In class B a pair would deliver 175 Watts at 5% distortion. The TZ40 was the successor to the T40.
The signal input would be 220 Volts peak to peak between the two grids. The anode load would be 7,000 Ω. Maximum anode dissipation is 40 Watts.
It is quite possible that the main use for this device would have been modulators for small AM transmitters.
The Hytron name and Made in USA. In view of the high voltages used the insulators are made of ceramic.
The filament is held under tension by the coil springs above the top ceramic insulator.
The graphite anode seen from the side together with the ceramic insulators.
The graphite anode from the base shows the wall thickness. Within the close wound control grid can be seen.
The UX4 base pins and on the base cap is the UK Government Crown and AM for the UK Air Ministry.
The balloon envelope is 51 mm in diameter and, excluding the UX4 base pins, is 145 mm tall.
