A pair of signal diodes are to be found in the DD620, A Mazda valve from 1934, intended for use in universal mains sets (transformerless for AC or DC use). For this application the heater cathode insulation has been designed to withstand a high voltage difference.

The large canopy is a screen, the two anodes are within. The lower anode is visible, but the top anode is hidden under the screen.

The balloon envelope is 40 mm in diameter and, excluding the B5 base pins, is 73 mm tall.

 
Pin Connections

B5	1	2	3	4	5
	a(1)	a(2)	h	h	k

 
Absolute Maximum Operating Conditions

Diode	Vh	Ah	mAa
	6.0	0.2	0.5

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 02 December 2007 {find valves by name}