4XP Cossor audio output triodes PX4 PP3/250 equivalent long cone semi-coated full getter quartet

Description

The Cossor 4XP also PX4 equivalent PP3/250 is a modern super power valve capable of supplying considerable output.

The efficiency of the valve is good for a triode and the sensitivity, as evidence by the mutual conductance of 7m/V is also high.

The maximum allowable dissipation of the anode is 12 watts .

The valve is of a directly heated type and if automatic bias is used, care must be taken that the resistance across the filament terminals is truly centre tapped, otherwise hum will result.

For large radiogram or amplifiers two of these valves in push-pull give an ouput adequate for almost all purposes.

Coated glass with white print on glass

Cossor 4XP tested 65mA, 66mA, 68mA and 67mA 100% emission.