EL5070

Power Pentode — Magnoval

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Philips

↗ r-type.org ↗ Radiomuseum

Known Equivalents & Substitutes

8608

Similar Tubes (Not Drop-In Compatible)

8233

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

E55L

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 EL5070 is the Philips/Mullard designation; 8608 is the RETMA/EIA 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 EL5070/8608 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).
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.

Pin Layout — Magnoval

1Internal Connection

2Suppressor Grid (g3)

Socket-Compatible Tubes ⚠ Not electrically compatible

8608

References

https://frank.pocnet.net/sheets/035/8/8608.pdf
https://www.r-type.org/exhib/aab0067.htm

Heater-to-Cathode Voltage (max)Heater-to-Cathode Voltage (max)180V

Max Grid ResistorMax Grid Resistor0.125MΩ

5.5mA

Anode ResistanceAnode Resistance20,000Ω

TransconductanceTransconductance45mA/V

Amplification Factor (μ)Amplification Factor30—

Cathode Resistor (self-bias)Cathode Resistor (self-bias)270Ω

Screen Grid (g2)

4Heater

5Heater

6Suppressor Grid (g3)

7Cathode

8Control Grid (g1)

9Cathode

tcPlate Cap