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X78

 
    
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The X78 is a triode hexode mixer from M-OV. The triode has to supply 10 volts pk-pk to drive the hexode mixer correctly.
The GEC label suggests that this valve was sold to the professional market rather than the consumer one.
The wire grids can be seen through the gap in the hexode anode.
The triode oscillator is located above the top mica and aligned at right angles to the mixer.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 47 mm tall.
References: 3002 & 1040. Type X78 was first introduced in 1949. See also 1949 adverts.

 

Pin Connections
B7G
1
2
3
4
5
6
7
g2,g4
g1
h,k
h
a
a(t)
g1(t),g3

 

Absolute Maximum Operating Conditions
Hexode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.3
250
75
0
4.5
3.4
0.7M
0.78

 

Absolute Maximum Operating Conditions
Triode
Va
Vg
mAa
gm
100
-1
10.0
2.8
Updated June 26, 2013.
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