TUBEOFILE
AL5 — Power Pentode, P8A | Tubeofile | Tubeofile
← Browse Medium quality — at least 60% of universal parameters and pins are present, but some key data is missing. Verify specific values against datasheets before critical use.
Known Equivalents & Substitutes
WE42 A70E TAL5 VAL5 4A27
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 Voltage 250V
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
1 2 3 4 5 6 7 8
1 Control Grid
2 Cathode
3 Heater
4
Socket-Compatible Tubes ⚠ Not electrically compatible
Screen Voltage (typical) Screen Voltage
275V
Grid 1 Bias Voltage Grid 1 Bias Voltage -18V
Anode Current Anode Current 72mA
Anode Resistance Anode Resistance 22,000Ω
Transconductance Transconductance 8.5mA/V
Output
Output Power Output Power (Class A SE, 5% THD) 8.8W
Heater
Heater Voltage Heater Voltage 4V
Heater Current Heater Current 2A
Heater
6 Metallization (external shield)
7 Suppressor Grid (internally connected to cathode)
TC Top Cap — Anode (top cap)