257A
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BrandWestern Electric
Classtriode
BaseWestern Electric 143B
Construction
Primary Typefilamentary triode
Envelopeglass
Base MaterialSmall, four-pin, thrust base
Sectionssingle
Filament / Heater
Materialfilamentary
Absolute Maximum Ratings
Plate Voltage135 V
Grid 1 Voltage-7.5 V
Audio Performance
Power Output50 W
Key Features
- Low filament power consumption
- Small metal cap grid terminal at the top of the bulb
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Class A Amplifier | 67.5V | 380 | 22500 | 8.5 | 0.93mA |
| Class A Amplifier | 90V | 510 | 16300 | 8.4 | 2.1mA |
| Maximum Operating Condition | 135V | 540 | 15600 | 8.4 | 2.5mA |
Application Notes
Audio-frequency and intermediate-frequency amplifier, detector, oscillator.
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