Tube-number record
8425-A
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BrandGeneral Electric
ClassSharp-cutoff Pentode
BaseMiniature 7-pin (B7G)
Filament6.3 V @ 0.3 mA
Construction
Primary TypePentode
EnvelopeT-5 1/2, Glass
Base MaterialGlass
SectionsSingle
Filament / Heater
Heater NotesAC or DC
Absolute Maximum Ratings
Plate Voltage310 V
Plate Dissipation3.2 W
Grid 2 Voltage310 V
H-C Voltage200 V
Audio Performance
Key Features
- Miniature sharp-cutoff pentode
- Industrial applications
- Unilaterally interchangeable with 8425
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Pentode Connection | 100 V | 4500 | 600000 | — | 4.8 mA |
| Pentode Connection | 250 V | 5500 | 1300000 | — | 7.4 mA |
| Pentode Connection | 250 V | 6200 | 1100000 | — | 10.5 mA |
| Triode Connection | 250 V | 6000 | — | 41 | 11.2 mA |
Application Notes
The equipment designer should design the equipment so that heater voltage is centered at the specified bogey value.
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