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P1

 
See also:
Cossor P1 Box - The Early Cossor Tin Hat Valves - Some Important British Valves - Cossor P1 Advert - Cossor P1, P2, W1, W2 & WR1 Advert - Cossor P1 & P2 Advert - Cossor P1 & P2 Advert - Cossor P1 & P2 Advert - Cossor P1, P2 & Wuncell Advert - Cossor P1 & P2 Advert - Cossor P1 & P2 Advert - Which Valve Shall I Buy?
    
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The Cossor P1 is a bright emitter valve and went into production in 1922. Cossor launched the valve as designed for detector and AF amplifier use. A sister valve the P2 was designed for HF use.
The early production valves had a metal shell base. Later production moved over to Bakelite moulded bases.
See P1.
Marconi held a patent for cylindrical anodes and grids and we believe that the electrode shape used by Cossor was a way to get round the patent.
The pictures above and below show the electrode shape. The anode is a fan or parabolic shape in one elevation and straight sided in the other. The filament is not visible but is fan shaped to match the anode. The grid can be seen as a series of hoops attached to a support tray.
The fan shaped anode seen face-on.
The grid is formed from a series of wire loops.
A view of the box shows diagrams of the electrodes and gives details of the valve. The box dimensions are 60 mm square and 130 mm long, the construction is strong cardboard and the internal packing is horse-hair.
The wide glass tube envelope is 27 mm in diameter and, excluding the B4 base pins, is 80 mm tall.
References: 1003 & 1004 Type P1 was first introduced in 1922.

 

Pin Connections
B4
1
2
3
4
a
g1
f
f

 

Absolute Maximum Operating Conditions
Triode
Vh
Va
3.5 - 4.0
30
Updated July 31, 2015.
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