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12AT7 tube: datasheets and technical data
Explore available pinout, electrical data and related types for the 12AT7 vacuum tube.
12AT7
The 12AT7 is a miniature twin triode with a high amplification factor. Datasheets also give it the designation ECC81. General Electric presents it as a grounded-grid radio-frequency amplifier or as a combined oscillator and mixer for frequencies below about 300 MHz under the datasheet's conditions. A Mazda Belvu datasheet also mentions use as an oscillator and audio preamplifier. These are different applications made possible by two separate triode sections in one noval envelope.
The centre-tapped heater can be supplied at 12.6 V and 150 mA or at 6.3 V and 300 mA. RCA and General Electric show both connections in their respective datasheets. For each triode, General Electric gives 300 V as the maximum design anode voltage and 2.5 W as maximum anode dissipation. These are limits for one section, not heater consumption or the output power of an audio stage.
The RCA datasheet even separates interelectrode capacitances according to whether the valve is used with a driven grid or a grounded grid. This is a significant detail at radio frequencies: capacitances between electrodes and external connections both affect circuit behaviour. Application tables for the 12AT7/ECC81 also give transconductance and current at specific operating points, so the valve's amplification factor should not be confused with the gain obtainable in every circuit.
A Brimar application report on the 12AT7/ECC81 is dated April 1950; an RCA datasheet is dated March 1954 and a General Electric datasheet February 1957. These publications document the type designation in technical literature of the period. On their own, they cannot establish an exact introduction date for the valve.
Tube images
Pinout and connections
Base: Noval (B9A)
Electrical data
Heater
Paired heater voltage/current configurations
- Heater voltage Vh
- 6.3 / 12.6 V
- Heater current Ih
- 0.3 / 0.15 A
Maximum ratings
- Maximum anode voltage Va max
- 300 V
- Maximum anode dissipation Pa max
- 2.5 W
- Maximum cathode current Ik max
- 0.015 A
- Maximum heater-to-cathode voltage Vhk max
- 90 V
Substitutes
Datasheet PDF
EL84 ECC83 12AX7 EL34 6L6GC 300B KT88 GZ34
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