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Tube Database (7,341 tube types · 1,270 archive entries)

Pre (2,630 tube types), Other (2,603 tube types), Power (1,292 tube types), Rectifier (816 tube types)
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421A vacuum tube outline illustration

Tube-number record

421A

0 archive entries

421A is a tube type in the TubeDatabase archive (class: Double Power Triode). Recorded specifications: brand Western Electric, construction Dual triode, socket Octal, maximum plate voltage 250 V, and maximum plate dissipation 13 W. The archive does not yet hold a photographed example of this type.

BrandWestern Electric
ClassDouble Power Triode
BaseOctal
Filament6.3 V @ 2500 mA

Construction

Primary TypeDual triode
EnvelopeGlass
Sections2

Filament / Heater

Heater NotesIndirectly heated

Absolute Maximum Ratings

Plate Voltage250 V

Typical Operation

ModePlate VGm (µmhos)Rp (Ω)µPlate mA
Class A1 (per section)135 V70002802125 mA

Application Notes

Commonly used in voltage regulators and OTL audio amplifier output stages.

Filters

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Manufacturers

Brands

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    Plate Dissipation13 W
    Cathode Current125 mA
    H-C Voltage300 V

    Audio Performance

    Power Output3.5 W
    Key Features
    • Low amplification factor
    • High transconductance
    • High plate current capability