75W plate dissipation, T4 base.
Data for the service type CV444 give 2A filament current at 10V.
Looks to be similar to 4242A with lower filament current drain.
Abmessungen (BHT) inkl. Stifte/Spitzli
x 194 x 57 mm / x 7.64 x 2.24 inch
Literatur
Babani, International Radio Tube Encyclopaedia p. 206 & 207
Universal Vade-Mecum, Electron Valves and Semiconductor Devices Section 259, p. 829
Taschenbuch zum Röhren-Codex 1948/49
MZ1-75: Mullard Power Valves for Industry and Communications
Achim Dassow