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EM4

Sensibly equivalent to:
CV1434
See also:
Tuning Indicators
    
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The EM4 is a dual sensitivity magic eye tuning indicator, electrically identical to the EM34 (IO base).
Unlike the beautiful EM4 this version of the EM4 has a plain domed top to the envelope and this style became the standard.
Mullard describe this device as suited to both receiver tuning indication and test equipment null indications. The grid voltage change is 0 - 5 Volts and 0 - 16 Volts. The display is viewed end on.
The Ct8 base was not a successful method of achieving long term low resistance contacts.
A close-up of another EM4 showing the triode section. The paint has been scraped off by the valve being inserted into a metal shield / mounting frame.
The underside of the display bowl.
The wide glass envelope is 25 mm in diameter and, excluding the Ct8 base contacts is 73 mm tall.
References: Datasheet & 1043. Type EM4 was first introduced in 1939.

 

Pin Connections
Ct8
1
2
3
4
5
6
7
8
-
h
h
k
a(1),a(d1)
g1
t
a(2),a(d1)

 

Absolute Maximum Operating Conditions
CRT
Vh
Ah
Va
Vg
mAa
6.3
0.2
250
-1
0.75
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated December31, 2012.
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