Tube-number record
3L31
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BrandTESLA
ClassPower Pentode
BaseMiniature 7-pin (B7G)
Construction
Primary TypePentode
EnvelopeGlass
Base MaterialGlass
SectionsSingle
Filament / Heater
MaterialOxide
Absolute Maximum Ratings
Plate Voltage150 V
Plate Dissipation2 W
Grid 2 Voltage135 V
Grid 1 Voltage-30 V
Cathode Current25 mA
Audio Performance
Typical THD10%
Power Output0.7 W
Key Features
- Directly heated cathode
- Miniature 7-pin base
- Series or parallel filament operation
- Suitable for Class A or Class C operation
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Audio Power Amplifier Class A (135V) | 135 V | 1900 | 90000 | 171 | 14.8 mA |
| Audio Power Amplifier Class A (150V) | 150 V | 1900 | 100000 | 190 | 13.3 mA |
| RF Power Amplifier 10 Mc/s | 150 V | — | — | — |
Application Notes
The suppressor grid is internally connected to the center tap of the filament. For series heating, the negative pole is connected to pin -f and the positive to +f. For parallel heating, pins -f and +f are connected together.
Datasheets
Datasheet: 3L31.pdf
Download PDFLoading datasheet...
Datasheets courtesy of Frank Philipse via Frank's Electron Tube Data Sheets.
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