The TZ20 is a power triode primarily designed for use as a zero bias class B modulator. The audio power that is possible from a pair of these 20 Watt anode dissipation triodes is up to 70 Watts.
The T20 is mainly for class C RF operation but can be used as a modulator when the grids are suitably biased. The advantage of the TZ20 is the ability to work with zero bias and this remove the need for a stable source of bias.
The rectangular anode seen from the side.
The high voltages employed make the use of ceramic insulators worthwhile.
The filament tension springs sit on the upper ceramic support.
The balloon envelope is 60 mm in diameter, and excluding the UX4 base pins is 143 mm tall.
