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KT81

Sensibly equivalent to:
7C5
See also:
Olympia Show 1947
    
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The KT81 is the first M-OV kinkless tetrode audio power valve with a pressed glass foot. We can not find details of how it performed in the market place, but it was not a valve produced for many years.
The detail photograph shows the 8 pin Loctal base. The pins are set directly in the glass base, the spigot and locating key are required to ensure correct placing of the equi-spaced pins.
See also KT81 for the Osram branded version.
The wide glass tube envelope is 31 mm in diameter and, excluding the B8B base pins, is 68 mm tall.
References: 4018 & 1040. Type KT81 was first introduced in 1947.

 

Pin Connections
B8B
1
2
3
4
5
6
7
8
h
a
g2
ic
ic
g1
k
h

 

Absolute Maximum Operating Conditions
Beam Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
gm
Pout
D
6.3
0.95
250
250
-4.4
40
7.5
10.8
4.3W
8%
Updated January 13, 2013.
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