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6BM8

Sensibly equivalent to:
6F3P 6PL12 ECL82
See also:
The Stereoplex Amplifier
    
Extras ▼

 

The 6BM8 is an audio triode plus output pentode of seven Watt anode dissipation. In this exhibit the output valve is a beam tetrode rather than a pentode.
The triode section has a amplification factor of 70, and this valve was much used in record players with crystal pickups. The latter had a relatively high output and when coupled with the single ended pentode output stage made effectively a single valve design. Only a rectifier was required to complete the line-up.
The pentode section looking along the grid axis. The bright plate entering the anode forms one side of the beam plate and also connects to the screen between the triode and the pentode (beam tetrode).
The triode section with the screen between the anode and the pentode anode. Both sections have the control grids wound on copper supports and the power section has heat radiating fins on the grid support rods.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins the valve is 69 mm long.
References: Datasheet & 1040. Type 6BM8 was first introduced in 1956.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
g1(t)
k,g3,S
g1
h
h
a
g2
k(t)
a(t)

 

Absolute Maximum Operating Conditions
Tetrode
Vh
Ah
Va
Vs
Vg
mAa
gm
6.3
0.78
200
200
-16
35
6.4

 

Absolute Maximum Operating Conditions
Triode
Va
mAa
gm
100
3.5
2.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated December14, 2015.
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