U251 @ The Valve Museum

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U251

Sensibly equivalent^¶ to:

U329

See also:

Valves and their Habits

Extras ▼

Mazda G8LSD Valve Collection

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: Data-sheet & 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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