Philips/Mullard high-gm frame-grid triode (gm=28 mA/V, Pa_max=4.2W); same Noval base but different pinout and lower dissipation
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Anode Voltage (max)300V
Anode Dissipation (max)Anode Dissipation (max)8W
Cathode Current (max)Cathode Current (max)70mA
Heater-to-Cathode Voltage (max)Heater-Cathode Voltage (max)100V
Max Grid Resistor
Notes
Produced exclusively by Telefunken; no other manufacturer made genuine EC8020 tubes. First referenced July 1965 in Radio-Mentor #7.
Datasheet is marked 'Vorläufige technische Daten' (Tentative data). Telefunken document numbers 011164 (page 1) and 020165 (page 3).
Frame-grid construction: tungsten grid wire wound at extreme tension on a molybdenum frame, cathode-grid spacing under 100 microns.
Five grid pins (1, 3, 6, 7, 9) must all be connected to suppress UHF parasitic oscillation. Grid stopper resistors recommended at socket.
Designed for grounded-grid (common-grid) amplifier topology at VHF/UHF frequencies. In audio use, typically operated as common-cathode voltage amplifier.
Grid dissipation limit is only 30 mW; positive grid voltage limited to +1V. Max grid resistor 50 kOhm (cathode bias via Rk).
Heater-cathode voltage rating is +/-100V with max Rf/k of 20 kOhm, permitting elevated heater potential for hum reduction in audio applications.
Guaranteed life of 10,000 hours averaged over 100 tubes, provided heater voltage is held within +/-5% of 6.3V.
Pin Layout — Noval
1Grid
2Cathode
3Grid
Socket-Compatible Tubes ⚠ Not electrically compatible