12AX7 ECC83 Dual Triode Valve Tested Measures 1.5mA Vacuum Tube Spare

12AX7 valve, tested and working, measuring 1.5 mA.

The 12AX7 (European equivalent ECC83) is a miniature dual (high-mu) triode fitted with a 9-pin Noval base, widely used in valve amplifier and preamplifier circuits.

Key specifications

• Tube Classification: Dual triode (twin triode)
• European Equivalent Designation: ECC83
• Amplification Factor (μ): 100
• Socket / Base: 9-pin miniature (Noval B9A / EIA 9A)
• Max Anode Voltage: 300 V

Specifications

• Audio Inputs: 1
• Year Manufactured: 1950s
• Compatible Brand: <UNKNOWN>
• Compatible Model: 12AX7
• Tube Classification: Dual triode (twin triode)
• European Equivalent Designation: ECC83
• Heater Voltage: 6.3 V (parallel) / 12.6 V (series)
• Amplification Factor (μ): 100
• Transconductance (Gm): 1.6 mA/V (1600 µmhos)
• Plate Resistance: 62.5 kΩ
• Heater Current: 300 mA (parallel) / 150 mA (series)
• Max Anode Dissipation: 1 W per section
• Max Anode Voltage: 300 V
• Physical Dimensions: Height: 2.2 in (56 mm); Diameter: 0.8 in (20 mm)
• Cathode Type: Indirectly heated
• Typical Operating Point (Class-A): Anode voltage 250 V; Anode current 1.2 mA; Bias −2 V
• Notable Equivalent / Variants: ECC83 (European), 7025 (low-noise US), 5751 (military, μ=70)
• Tube Type: Miniature dual (twin) triode — high-mu
• Socket / Base: 9-pin miniature (Noval B9A / EIA 9A)