EL3N — Power Pentode, P8A | Tubeofile

EL3N

Power Pentode — P8A

Philips

Known Equivalents & Substitutes

PP6BS

Similar Tubes (Not Drop-In Compatible)

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

Electrically identical original with older P-base — different base type

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)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 Current

Output

Output PowerOutput Power4.5W

Load ImpedanceLoad Impedance7,000Ω

other

μg2g1μg2g123—

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current0.9A

Notes

The tube MUST be used with automatic or semi-automatic bias (cathode bias) only — fixed bias is explicitly prohibited in the Philips datasheet.
Anode connection is via top cap, not on the base. The P8A side-contact base carries heater, cathode, grids, and metallization only.
Screen dissipation has two limits: max 1.2 W at zero signal (idle) and max 2.5 W at maximum output power.
The EL3N is the 6.3 V parallel-heated version of the EL3 family. The original EL3 had a different heater arrangement. AL4 is a related earlier type.
No direct American or Noval/Octal equivalents exist due to the unique P8A side-contact base.
Widely used in triode-connected Sakuma-style SE amplifiers, delivering approximately 1 W output in triode mode. No manufacturer triode data published; μg2g1 = 23 suggests triode μ ≈ 23.
Class AB push-pull (2× EL3N): 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

References