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LP4

Sensibly equivalent to:
4XP AC044 CV1168 NR44 P12/250 PP3/250 PX4
See also:
Ferranti Advert, March 1935
    
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The LP4 is Ferranti's version of the PX4, one of the classic audio power triode valves. We believe, however, that this exhibit is in fact a rebranded Marconi Osram PX4.
Ferrantis did manufacture some of there own valves during the later 1930s but their 'home-brewed' LP4s were bulbous and stumpy. After WWII Ferranti's tended to buy in and re-label other manufacturers' valves; this is one of them.
The valve in the photo has blackened fins spot-welded to a shiny anode. This shows that it is of post-1938 manufacture and has been uprated from 250 V and 12 Watt dissipation to 300 V and 15 Watt dissipation. From around 1950 the fins were omitted but the outer surface of the anode was given a grey coating instead.
The classic envelope is 48 mm in diameter and, excluding the B4 base pins, is 120 mm tall.
References: Datasheet & 1040. Type LP4 was first introduced in 1933.

 

Pin Connections
B4
1
2
3
4
a
g1
f
f

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
Vg
mAa
ra
gm
Pout
D
4.0
1.0
300
-50
50
830
6.0
4.5
4%
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 26, 2013.
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