Tube-number record
257A
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BrandWestern Electric
Classtriode
BaseSpecial / none
Construction
Primary TypeTriode
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 | 67.5 V | 380 | 22500 | 8.5 | 0.93 mA |
| Class A Amplifier | 90 V | 510 | 16300 | 8.4 | 2.1 mA |
| Maximum Operating Condition | 135 V | 540 | 15600 | 8.4 | 2.5 mA |
Application Notes
Audio-frequency and intermediate-frequency amplifier, detector, oscillator.
Datasheets
Datasheet: 257A.pdf
Download PDFLoading datasheet...
Datasheets courtesy of Frank Philipse via Frank's Electron Tube Data Sheets.
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