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U31

Sensibly equivalent to:
25Z4 CV3753
See also:
Osram KT2, KT63, KT61, KT66, PX4, U50, KT76, KT33C, KT71, U76 & U31 Advert
    
Extras ▼

 

The U31 half wave rectifier was designed for series heater use.
The maximum reservoir capacitor specified is 32 µF and the minimum effective series resistance has to be 100 Ohms.
See also U31.
The remains of the Marconi brand label.
The coiled insulated heater passes through the rectangular cathode four times.
The classic envelope is 45 mm in diameter, and excluding the IO base pins, is 103 mm tall.
References: Datasheet, 1040 & 1043. Type U31 was first introduced in 1937.

 

Pin Connections
IO
1
2
3
4
5
6
7
8
ic
h
-
-
a
-
h
k

 

Absolute Maximum Operating Conditions
Rectifier
Vh
Ah
Va
mAs
26
0.3
250
120
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated March 17, 2019.
shape:classic construction:pinch type:rectifier.hw age:1930.1940 base:io heater:300ma pins:8 pin:1.ic pin:2.h pin:3.- pin:4.- pin:5.a pin:6.- pin:7.h pin:8.k
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