ECH35

Triode-Hexode — Octal

Philips

Known Equivalents & Substitutes

ARTH2

Similar Tubes (Not Drop-In Compatible)

Earlier side-contact base version — not pin-compatible

ECH81

Later Noval-base triode-heptode replacement — not pin-compatible

Electrical Specifications

Section 1 — Triode (Oscillator)

Absolute Maximum

Anode Voltage (max)Anode Voltage (max)550V

Anode Dissipation (max)Anode Dissipation (max)1.5W

Max Grid ResistorGrid Resistance (max)100MΩ

Typical Operating

Anode Voltage (typical)Anode Voltage (typical)250V

Anode CurrentAnode Current3.3mA

other

Oscillator Voltage (Vosc)Oscillator Voltage (Vosc)8Veff

Section 2 — Hexode (Mixer)

Absolute Maximum

Anode Voltage (max)Anode Voltage (max)550V

Screen Voltage (max)Screen Voltage (max, Ia<0.5mA)200V

Anode Dissipation (max)Anode Dissipation (max)1.2W

Screen Dissipation (max)Screen Dissipation (max)0.6W

Typical Operating

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current0.2A

Notes

Triode and hexode sections share a common cathode.
Screen grid supply through a potentiometer (R1, R2) from B+ for the hexode section.
The triode section is used as the local oscillator; the hexode section as frequency changer/mixer.
Hexode conversion conductance Sc = 650 uA/V at Va=250V, Vg2+g4=200V.
Limiting values: hexode Va_max = 550V, Vs_max = 300V; triode Va_max = 550V.

Pin Layout — Octal

1Hexode Anode

2Hexode Screen Grid (g2+g4)

3Common Cathode

4

References