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DF1

Sensibly equivalent to:
CV2907
    
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The Ever Ready DF1 is a battery variable μ pentode with a grid range of zero to minus four Volts. Use in a superhet radio receiver would be as IF amplifier controlled by an AGC voltage.
Ever Ready were noted for their dry batteries, valves were produced initially but later supplied by Mullard.
Thanks to Stef Niewiadomski for sending in the picture and base connections.
The wide glass tube envelope is 30 mm in diameter, and excluding the Ct8 base pins is 90 mm tall.
References: 1043 & 1040. Type DF1 was first introduced in 1939.

 

Pin Connections
Ct8
1
2
3
4
5
6
7
8
tc
m
f(+)
f(-)
-
-
-
g2
a
g1

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
1.4
0.05
90
90
0
1.2
0.3
1.5M
0.75
Updated August 04, 2013.
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