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DF91

Sensibly equivalent to:
1F3 1T4 CV785 W17
See also:
1T4 Exploded
    
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The DF91 is a is a miniature screened pentode for dry battery operation. It was designed for broadcast radio reception and is a variable μ RF device.
See also 1T4
The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 47 mm tall.
References: Datasheet & 1040. Type DF91 was first introduced in 1947.

 

Pin Connections
B7G
1
2
3
4
5
6
7
f-
a
g2
ic
f-
g1
f+

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
1.4
0.05
90
67.5
0
3.5
1.5
0.5M
0.9
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 04, 2013.
shape:thin.glass.tube construction:all.glass type:pentode age:1940.1950 base:b7g heater:1.4v pins:7 pin:1.f- pin:2.a pin:3.g2 pin:4.ic pin:5.f- pin:6.g1 pin:7.f+
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