The SG215 was introduced in 1928 and by 1920 the Ediswan name had changed to Mazda. It is a screen grid or tetrode valve for RF amplification in receivers.

The detail photograph is of the control grid. It has the appearance of being hand made rather than the perfectly regular structure expected of a machine wound grid.

The balloon envelope is 43 mm in diameter and, excluding the B4 base pins, is 117 mm tall.

 
Pin Connections

B4	1	2	3	4	tc
	g2	g1	f	f	a

 
Absolute Maximum Operating Conditions

Tetrode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	2.0	0.15	150	60	-1.5	1.5	0.25	1.5M	0.85

This exhibit was last updated on 02 December 2007