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8D8

 
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The 8D8 is a low microphony audio amplifier pentode. The introduction was in 1960 and in 1961 the data-book lists it as a maintenance type.
The 8D8 is pin compatible with the EF86 and slightly different in characteristics.
The resistance to vibration and thus microphony is achieved by the use of double micas both top and bottom.
Screens exist down to the pins as well as above the top mica.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 47 mm tall.
References: Datasheet & 4062. Type 8D8 was first introduced in 1960.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
g2
s
k
h
h
a
s
g3
g1

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.15
250
140
-2.0
3.0
0.6
2.5M
1.9
PDF scanned from an original document held by the museum
Updated October 13, 2016.
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