ECC81 Mullard tube/12AT7 RCA valve/ 12AT7 tube dataGeneral InformationAn indirectly heated, oxide coated, twin cathode double triode. Each triode is a separate unit, the heaters being the only common connection. As a result it is possible to use each unit for different functions or both in cascade. The feature of a heater tap allows for both A.C. & D.C. supply. CATHODE Indirectly heated by A.C. or D.C.; series or parallel supply
Series - pins 9-(4+5) parallel - pins 4+5
Heater Voltage 12.6 6.3 V Heater current 150 300 mA In case of series supply a current limiting device must be inserted in the heater circuit for limiting the current when switching on. Max D.C. Heater –Cathode Potential 250 V MAXIMUM RATINGS (each triode unit)Maximum anode voltage Va0 550 V Va 300 V Maximum anode dissipation Wa 2.5 W Maximum Cathode Current Ik 15 mA Maximum Grid Voltag -Vg 50 V Maximum Grid Resistance Rg 1 MΩ (automatic bias) Maximum Cathode to heater voltage Vkf 90 V TYPICAL OPERATION CONDITIONS & CHARACTERISTICSAnode Voltage Va 100 170 200 250 V Grid Voltage Vg -1.0 -1.0 -1.0 -2.0 V Anode Current Ia 3.0 8.5 11.5 10 mA Transconductance S 3.75 5.9 6.7 5.5 mA/V Amplification Factor µ 62 66 70 60 Internal resistance Ri 16.5 11 10.5 11 Kω DIMENSIONSMaximum overall length 55.6 mm Maximum seated height 49.2 mm Maximum diameter 22.2 mm Base Noval B9A BASE CONNECTIONSPin1 Anode ) Pin4 Heater Pin6 Anode ) Pin9 HeaterTap CAPACITIES (Approx) (Measured without shield)Grounded Cathode Operation First triode Unit Second Triode Unit
Grid – Anode 1.45 1.45 pF Grid – Cathode, Heater 2.5 2.5 pF Grid – Cathode, Heater 0.45 0.35 pF Heater – Cathode 2.5 2.5 pF
CAPACITIES (Approx) cont.
Grid 1 – Anode 2 0.20 pF Grid 2 - Anode 1 0.20 pF Anode 1 – Anode2 0.40 pF max. Grid 1 – Grid 2 0.005 pF max.
Grounded Grid Operation
First triode Unit Second Triode Unit
Anode – Cathode 0.15 0.15 pF Cathode – Grid, Heater 5 5 pF Anode – Grid, Heater 1.6 1.5 pF |