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8LT8

 
    
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The 8LT8 is a double diode sharp cut-off pentode designed for use in television receivers. The pentode was designed for line oscillator use and the diodes are used in line AFC discriminator circuits.
This design came in three heater variants: 6LT8 - 6.3 V @ 0.6 A, the 8LT8 and the 11LT8 with an 11.4 Volt heater running at 0.315 Amps.
The main picture shows the two diodes as bright anodes mounted one above the other on the common cylindrical cathode.
The pentode is in fact a beam tetrode. The grey beam forming plate can be seen on the left inside the anode end straps. The twin diodes are on the right.
Looking directly along the grid axis of the beam tetrode.
The thin glass tube envelope is 21 mm in diameter, and excluding the B9A base pins is 47 mm tall.
Reference: Datasheet. Type 8LT8 was first introduced in 1965.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
k,g3,s
g2
a
h
h
a(d2)
k(d1),k(d2)
a(d1)
g1

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
8.1
0.45
125
125
-3.5
10.0
3.4
0.2M
13.0
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 02, 2015.
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