EL3

Power Pentode — P8A

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Philips

↗ Radiomuseum

Known Equivalents & Substitutes

3REP6TEL3VEL3

Similar Tubes (Not Drop-In Compatible)

AL3

4 V heater version — not interchangeable without heater modification

EL11

Electrically identical but Y8A steel base — not pin-compatible with P8A side-contact sockets

EL3G

Glass envelope variant — check base compatibility

EL3N

Improved successor with reduced heater current (0.9 A vs 1.2 A) — same P8A base, electrically near-identical

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Anode Voltage (max)250V

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

Anode Dissipation (max)Anode Dissipation (max)9W

Screen Dissipation (max)Screen Dissipation (max, at max output)2.5W

Cathode Current (max)

Notes

The EL3 is the original 1936 design with 1.2 A heater current. The EL3N successor (1938) reduced this to 0.9 A using a more efficient profile-cathode while maintaining the same electrical characteristics.
Only specimens with straight cylindrical bulbs are authentic EL3; dome-bulb variants are actually EL3Ns.
Anode connection is via top cap. The P8A side-contact base carries heater, cathode, grids, and metallization.
Cathode-bias only — fixed bias is prohibited per the Philips datasheet.
Screen dissipation: max 1.2 W at zero signal, max 2.5 W at maximum output power.
Class A SE: Va = 250 V, Vg2 = 250 V, Rk = 150 Ω, rl = 7 kΩ delivers 4.5 W.
Class AB push-pull (2x): Va = 250 V, Vg2 = 250 V, Rk = 140 Ω, Raa = 10 kΩ delivers 8.2 W.

Pin Layout — P8A

1Control Grid

2Cathode

3Heater

Socket-Compatible Tubes ⚠ Not electrically compatible

EL2 EL3N EL5 EL53

Cathode Current (max)

55mA

Heater-to-Cathode Voltage (max)Heater-to-Cathode Voltage (max)100V

Max Grid ResistorMax Grid Resistor1MΩ

Typical Operating

Anode Voltage (typical)Anode Voltage250V

Screen Voltage (typical)Screen Voltage250V

Grid 1 Bias VoltageGrid 1 Bias Voltage-6V

Anode CurrentAnode Current36mA

Screen CurrentScreen Current4mA

Anode ResistanceAnode Resistance50,000Ω

TransconductanceTransconductance9mA/V

Cathode Resistor (self-bias)Cathode Resistor (self-bias)150Ω

Output

Output PowerOutput Power4.5W

Load ImpedanceLoad Impedance7,000Ω

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current1.2A

Heater

5Screen Grid

6Metallization (external shield)

7Suppressor Grid (internally connected to cathode)

8No Connection

TCTop Cap —Anode (top cap)