The GZ30 indirectly heated full wave rectifier was designed for larger domestic equipment and audio amplifiers. The maximum reservoir capacitor was 50 µF and the minimum effective series resistance had to be 380 Ω. The maximum peak inverse voltage was 1.4 kV.
The twin rectifiers. The anodes in plan are X shaped.
Here the cathode tube can be seen together with a face view of one anode. The anode reaches down to the top of the moulded base as the construction uses the modern glass foot technique rather than a pinch.
The wide glass envelope is 28 mm in diameter and, excluding the IO base pins, is 69 mm tall.
References: Data-sheet, 1040. Type GZ30 was first introduced in 1940.