The 35Z5GT is a half wave rectifier for heater chain service. The maximum reservoir capacitor is 40 μF and the surge limiting series resistance must be at least 100 Ohms.
The heater is tapped to allow a dial lamp to be wired in parallel with a portion of the heater. The lamp lasts longer as the surge is reduced and the radio continues to work with a broken dial lamp.
The Arcturus brand.
The folded and carbonised anode forming a cylindrical cavity in the centre to surround the cathode.
The wide glass tube envelope is 29 mm in diameter, and excluding the IO base pins is 70 mm tall.
References: Data-sheet, 3002 & 1040. Type 35Z5GT was first introduced in 1939. See also1939 adverts.