285A
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BrandWestern Electric
ClassPentode
BaseWestern Electric 141A
Filament2V @ 1.6mA
Construction
Primary TypeSuppressor-grid pentode
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
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
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Recommended 1 | 135V | 860 | 140000 | 120 | 7.5mA |
| Recommended 2 | 180V | 880 | 153000 | 135 | 8.8mA |
| Maximum Operating Condition | 250V | 1020 | 137000 | 140 | 12.4mA |
Application Notes
Audio-frequency amplifier where power outputs of approximately one watt or less are required.
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