8608 — Power Pentode, Magnoval | Tubeofile

8608

Power Pentode — Magnoval

Amperex

Known Equivalents & Substitutes

Similar Tubes (Not Drop-In Compatible)

8233

Related power pentode on Magnoval base — similar design, anode on base pin, different pinout

Electrically equivalent power pentode on Magnoval base — identical characteristics but anode on base pin 1 instead of top cap, not pin-compatible

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Anode Voltage (max, zero plate current)300V

Screen Voltage (max)Screen Voltage (max, zero screen current)300V

Anode Dissipation (max)Anode Dissipation (max)10W

Screen Dissipation (max)Screen Dissipation (max)1.5W

Cathode Current (max)Cathode Current (max)75mA

Typical Operating

Anode Voltage (typical)Anode Voltage125V

Screen Voltage (typical)Screen Voltage125V

Grid 1 Bias VoltageGrid 1 Bias Voltage-3V

Anode CurrentAnode Current50mA

Screen CurrentScreen Current

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current0.6A

Notes

The 8608 is the RETMA/EIA designation; EL5070 is the Philips/Mullard designation for the same tube.
Created by Amperex at Tektronix' request — a modification of the 8233 bringing the anode connection out to a top contact to reduce output capacitance.
Electrically equivalent to the E55L but NOT pin-compatible: the E55L has the anode on base pin 1, while the 8608/EL5070 has pin 1 as internal connection and the anode on a top cap.
Widely used as the Y-amplifier final stage in Tektronix oscilloscopes (549, 556, 3A7). Tektronix part number 154-0491-00.
Amperex datasheet dated 12/65 marked 'Tentative Data'.
In triode mode (plate connected to screen grid): gm=50 mA/V, mu=30, ra=600 Ω.
Max Va of 300V applies at zero plate current only; operating Va max is 150V. Same for screen grid.

Pin Layout — Magnoval

1Internal Connection

2Suppressor Grid (g3)

Socket-Compatible Tubes ⚠ Not electrically compatible

References