AL5 — Power Pentode, P8A | TubeofileKnown Equivalents & Substitutes
WE42A70ETAL5VAL54A27
Similar Tubes (Not Drop-In Compatible)
Factory-selected for 375 V operation — same base, higher voltage rating Related 18 W pentode with Y8A base — different base, not pin-compatible Octal-base equivalent of EL5 — different base, not pin-compatible 6.3 V heater version — electrically identical but different heater voltage, not interchangeable Electrical Specifications
Absolute Maximum
Anode Voltage (max)Anode Voltage (max)275V
Screen Voltage (max)Screen Voltage (max)275V
Anode Dissipation (max)Anode Dissipation (max)18W
Typical Operating
Anode Voltage (typical)Anode Voltage250V
Notes
- The AL5 is the 4 V heater version of the EL5. 'A' prefix = 4 V heater in the Philips naming convention.
- Pa_max = 18 W — approximately 8.8 W single-ended output, 20 W push-pull AB at 5% distortion.
- Anode connection via top cap. P8A side-contact base.
- Standard operation: Va = 250 V, Vg2 = 275 V.
- AL5/325 and AL5/375 are voltage-selected variants rated for higher anode voltages.
Pin Layout — P8A
1Control Grid
2Cathode
3Heater
4
Socket-Compatible Tubes ⚠ Not electrically compatible
Screen Voltage (typical)Screen Voltage
275V
Grid 1 Bias VoltageGrid 1 Bias Voltage-18V
Anode CurrentAnode Current72mA
Anode ResistanceAnode Resistance22,000Ω
TransconductanceTransconductance8.5mA/V
Output
Output PowerOutput Power (Class A SE, 5% THD)8.8W
Heater
Heater VoltageHeater Voltage4V
Heater CurrentHeater Current2A
Absolute Maximum
Anode Voltage (max)Anode Voltage (max)275V
Screen Voltage (max)Screen Voltage (max)275V
Anode Dissipation (max)Anode Dissipation (max)18W
Typical Operating
Anode Voltage (typical)Anode Voltage (typical)250V
Screen Voltage (typical)Screen Voltage (typical)275V
Grid 1 Bias VoltageGrid 1 Bias Voltage-18V
Anode CurrentAnode Current72mA
TransconductanceTransconductance
Output
Output PowerOutput Power (Class A SE, 5% THD)8.8W
Heater
6Metallization (external shield)
7Suppressor Grid (internally connected to cathode)
TCTop Cap —Anode (top cap)
8.5mA/V