This Zaerix EZ81 was made in the GDR (East Germany) and is a high current B9A rectifier, the low power B9A rectifier was the 90 mA EZ80.
In use the maximum reservoir capacitor would be limited to 50 μF and to prevent damage by excess current an effective series resistance of 230 Ω is used.
The anodes are identical with one inverted. The shape is an X in plan view and the upper anode is rotated with respect to the lower anode. In side view one side is double height to offer greater radiation area. The cathode is common and mounted centrally.
This view shows the anode construction in more detail and shows how the sheets are stitched together.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 69 mm tall.
References: Data-sheet, 3002 & 1040. Type EZ81 was first introduced in 1954. See also1954 adverts.
