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

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285A vacuum tube outline illustration

Tube-number record

285A

0 archive entries

285A is a tube type in the TubeDatabase archive (class: Pentode). Recorded specifications: brand Western Electric, construction Pentode, base Medium, five-pin base with bayonet pin, socket Special / none, and maximum plate voltage 250 V. The archive does not yet hold a photographed example of this type.

BrandWestern Electric
ClassPentode
BaseSpecial / none
Filament2 V @ 1.6 mA

Construction

Primary TypePentode
EnvelopeGlass
Base MaterialMedium, five-pin base with bayonet pin
SectionsSingle

Filament / Heater

Heater NotesDesigned to operate on a voltage basis; AC or DC.

Absolute Maximum Ratings

Typical Operation

ModePlate VGm (µmhos)Rp (Ω)µPlate mA
Recommended 1135 V8601400001207.5 mA
Recommended 2180 V8801530001358.8 mA
Maximum Operating Condition250 V102013700014012.4 mA

Application Notes

Audio-frequency amplifier where power outputs of approximately one watt or less are required.

Datasheets

Datasheet: 285A.pdf

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Datasheets courtesy of Frank Philipse via Frank's Electron Tube Data Sheets.

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Manufacturers

Brands

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    Plate Voltage250 V
    Grid 2 Voltage200 V
    Cathode Current12.5 mA
    H-C Voltage90 V

    Audio Performance

    Power Output1.85 W
    Key Features
    • Low-power suppressor-grid pentode
    • Indirectly heated cathode
    • Suppressor-grid permanently connected to cathode
    • Small metal cap control-grid terminal