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1A3

Sensibly equivalent to:
1D13 CV753 DA90
    
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The 1A3 is a signal diode and features a 1.4 Volt indirectly heated cathode. Normally dry battery valves are directly heated. Such a valve would find applications where the cathode is not taken to ground or where the filaments of other valves are run in series from a higher voltage supply. Two such valves could be used in a discriminator in an FM radio in the 1950s.
The heater wire is a single thread running vertically through the anode cavity.
Seen from the side the anode can be seen as two fins with a central cylindrical cavity for the cathode.
The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 45 mm tall.
References: Datasheet & 3002 Type 1A3 was first introduced in 1943.

 

Pin Connections
B7G
1
2
3
4
5
6
7
h
a
k
-
-
a
h

 

Absolute Maximum Operating Conditions
Diode
Vh
Ah
Va
mAa
1.4
0.15
117
0.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 05, 2013.
shape:thin.glass.tube construction:all.glass type:diode age:1940.1950 base:b7g heater:1.4v pins:7 pin:1.h pin:2.a pin:3.k pin:4.- pin:5.- pin:6.a pin:7.h
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