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U404

Sensibly equivalent to:
U118 U145
See also:
Mazda 10C1, 10F9, 10LD11, 10P13 & U404 Advert - Mazda 10LD11, 10P13, 10P14 & U404 Advert - Mazda 10F9 + 10C1, 10LD11, 10P13, 10P14 & U404 Advert
    
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The U404 is a half-wave rectifier for AC/DC radio sets without a transformer. The 100 mA heater is for heater chain use across the mains.
The U404 datasheet gives the maximum reservoir capacitor as 16μF and has a graph for a reservoir capacitor of 32μF. The Wireless World book gives the maximum reservoir capacitor as being 50 μF and must have 180 Ω of series resistance to limit the current surge. In all cases the design has to limit the charging peak current to within the cathode rating of 700mA.
Thanks to Jonathan Marsh for sending the image.
The thin glass tube envelope is 19 mm in diameter, and excluding the B8A base pins is 60 mm tall.
References: Datasheet & 1040. Type U404 was first introduced in 1947.

 

Pin Connections
B8A
1
2
3
4
5
6
7
8
h
a
-
ic
ic
ic
k
h

 

Absolute Maximum Operating Conditions
Rectifier
Vh
Ah
Va
mAa
40
0.1
250
90
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated March 20, 2017.
shape:thin.glass.tube construction:all.glass type:rectifier.hw age:1940.1950 base:b8a heater:100ma pins:8 pin:1.h pin:2.a pin:3.- pin:4.ic pin:5.ic pin:6.ic pin:7.k pin:8.h
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