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31 Vacuum Tube New and Used

$17.50
31 Vacuum Tube New and Used
31 Vacuum Tube New and Used

Home / Shop

31 Vacuum Tube New and Used

$17.50
Model Number: 31NEW
Type 31 4-pin directly heated power amplifier triode tube for vintage battery-operated radio audio output circuits. Available in new and used condition.
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Categories: Vacuum Tubes and Accessories
Manufacturer: Multiple Manufacturers
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  • Description
  • Specifications

The Type 31 (originally designated UX-231 or CX-331) is a 4-pin directly heated power amplifier triode designed for audio output stages in battery-operated radio receivers. Introduced by RCA and Cunningham in 1930 alongside the Type 30, it features a 2.0-volt filament optimized for low current draw in portable and farm-battery receivers, capable of driving magnetic or dynamic speakers with minimal battery drain.

  • Tube Function: Directly Heated Power Amplifier Triode

  • Base Design: 4-Pin Standard Base (UX4 / Bayonet)

  • Glass Shape: ST-12 or Globe (S-12)

  • Filament Voltage: 2.0 Volts DC

  • Filament Current: 0.13 Amps (130 mA)

  • Maximum Plate Voltage: 180 Volts DC

  • Amplification Factor (Mu): 3.8

  • Plate Resistance: 4,100 Ohms

  • Transconductance: 925 micromhos

  • Typical Power Output: 0.375 Watts (375 mW at 180V Plate)

  • Cathode Heating Method: Direct (Filament)