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U251

Sensibly equivalent to:
U329
See also:
Valves and their Habits
    
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The U251 is a television efficiency diode. It has a PIV rating of 7,000 Volts whereas the equivalent U329 is rated at 7,500 Volts.
Considerable energy is fed to the line deflection coils and this has to dissipate during flyback. The efficiency diode channels this energy back to the supply rail smoothing capacitors for use on the next line scan.
The central cylindrical anode space is surrounded by four heat dissipating fins each at right angles to one another..
The thin glass tube envelope is 21 mm in diameter and excluding the B9A base pins the length is 72 mm.
References: Datasheet & 1040

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
tc
ic
ic
ic
h
h
ic
ic
ic
a
k

 

Absolute Maximum Operating Conditions
Rectifier
Vh
Ah
Vg
mAa
17
0.3
-1
150
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated December29, 2012.
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