The PP24 is a high impedance pentode for radio applications. The control grid is connected to the top cap. The top cap is of the metal cylinder type not the early bakelite and screw cap variety. This suggests the later half of the 1930s for the date of origin and indeed it was introduced in 1937.
The PP24 is fitted with a British B7 base and the CL2 of the pdf has a Ct8 base but is otherwise the same valve.
The internal metalisation obscures most of the inside. With a glass it is possible to see some detail. The suppressor grid is a wide pitch helix close to the bright anode cylinder. The inner grids are close together and the control grid is close to the large diameter oxide coated cathode tube.
The classic envelope is 45 mm in diameter, and excluding the B7 base pins is 120 mm tall.
References: Datasheet & 1043. Type PP24 was first introduced in 1937.
Absolute Maximum Operating Conditions¶
Updated December14, 2012.