EL50

Power Pentode — B8A

Philips

Known Equivalents & Substitutes

465410E/131

Similar Tubes (Not Drop-In Compatible)

Octal base version with similar ratings — not pin-compatible with B8A base EL50

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Anode Voltage (max)600V

Screen Voltage (max)Screen Voltage (max)275V

Anode Dissipation (max)Anode Dissipation (max)18W

Screen Dissipation (max)Screen Dissipation (max, estimated)2.5W

Typical Operating

Anode Voltage (typical)Anode Voltage (typical)375V

Screen Voltage (typical)Screen Voltage (typical)275V

Grid 1 Bias VoltageGrid 1 Bias Voltage-17.5V

Anode CurrentAnode Current48mA

Screen CurrentScreen Current

Output

Output PowerOutput Power (single-ended)8.8W

Load ImpedanceLoad Impedance (single-ended)3,500Ω

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current1.35A

Notes

European side-contact base (P8A/Ct8) with top-cap anode — no direct American or Octal/Noval equivalents exist.
EL39 and 4654K are Octal-based variants with similar characteristics but are not pin-compatible.
The EL50 belongs to the Philips all-glass P8A tube family that includes the EF50 RF pentode — described as 'next to the magnetron, the most important tube from World War II.' The EF50 was critical to British Chain Home radar; its pressed-glass base technology (shared with the EL50) was a Philips innovation that became the basis for all modern tube construction. Components for the EF50 were smuggled out of the Philips factory in Eindhoven on the eve of the German invasion of the Netherlands in May 1940.

Pin Layout — B8A

1No Connection

2Heater

3Heater

Socket-Compatible Tubes ⚠ Not electrically compatible

References