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U201

Sensibly equivalent to:
CY31
See also:
Ediswan Advert, December 1948
    
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The U201 is a half wave HT rectifier designed for use on a 200 mA heater chain. The maximum reservoir capacitor is 16 µF and the minimum series resistance needs to be 47 Ohms to prevent damage to the device by excessive current peaks.
The advert shows that it was designed for post-war TV receivers from 1948 but the equivalent CY31 was issued in 1939 and it is possible that the U201 was designed much earlier.
The wide glass tube envelope is 28 mm in diameter and, excluding the IO base pins, is 80 mm tall.
References: Data-sheet & 1040. Type U201 was first introduced in 1948. See also 1948 adverts.

 

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

 

Absolute Maximum Operating Conditions
Rectifier
Vh
Ah
Va
mAa
20
0.2
250
90
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 07, 2022.
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