286A
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BrandWestern Electric
ClassPentode
BaseStandard six-contact (Western Electric 144B)
Filament2V @ 1600mA
Construction
Primary TypeVariable-mu voltage-amplifier pentode
EnvelopeGlass with top cap
Base MaterialMedium six-pin
SectionsSingle
Filament / Heater
Heater NotesIndirectly heated cathode; designed to operate on a voltage basis
Absolute Maximum Ratings
Plate Voltage250 V
Grid 1 Voltage-45 V
H-C Voltage30 V
Audio Performance
Key Features
- Variable-mu characteristic
- Suppressor-grid pentode
- Shielded modulator capability
- High frequency capability
- Separate terminal for each of the three grids
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Voltage Amplifier | 135V | 1190 | 400000 | 475 | 6.1mA |
| Voltage Amplifier | 180V | 1200 | 700000 | 850 | 6.2mA |
| Maximum Operating Conditions | 250V | 1210 | 1050000 | 1275 | 6.3mA |
| Nominal cut-off | 250V | 5 | - | - | - |
Application Notes
To avoid undesired feed-back, use close-fitting shields, filter battery leads, and avoid common impedances. For amplifier applications, connect suppressor grid directly to cathode.
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