The EM1 is a magic eye tuning indicator. The control voltage swing required is 5 Volts to move from minimum to maximum shadow.

The window is circular with a bowl shaped target.

A second example of the EM1 in poor cosmetic condition. The electrodes forming the display are fully revealed.

Where the paint has flaked away the inner triode amplifier anode can be seen. As a low power voltage amplifier the anode is left bright and is quite small.

The wide glass tube envelope is 25 mm in diameter and, excluding the Ct8 base pins, is 71 mm tall.

 
Pin Connections

Ct8	1	2	3	4	5	6	7	8
	-	h	h	k	-	g1	t	a

 
Absolute Maximum Operating Conditions

CRT	Vh	Ah	Va	mAa
	6.3	0.2	250	0.13

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 25 November 2007 {find valves by name}