309A
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BrandWestern Electric
ClassVoltage amplifier, variable-mu pentode
BaseStandard, five-contact type (e.g., Western Electric 141A)
Filament10V @ 320mA
Construction
Primary TypePentode
EnvelopeST-12
Base MaterialSmall five-pin with silver-plated pins
SectionsSingle
Filament / Heater
Heater NotesDirect-current heater supply may be required for exceptionally low tube noise in audio-frequency applications.
Absolute Maximum Ratings
Plate Voltage250 V
Grid 2 Voltage75 V
H-C Voltage150 V
Audio Performance
Key Features
- Variable-mu
- Low noise
- Internal suppressor-to-cathode connection
- Silver-plated pins
- Top cap control-grid terminal
- Minimize microphonic noise
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Typical Operation 1 | 135V | 1090 | 700000 | 760 | 4.75mA |
| Typical Operation 2 | 180V | 1100 | 1000000 | 1100 | 4.8mA |
| Maximum Operating Conditions | 250V | 1110 | 1300000 | 1450 | 4.85mA |
| Nominal Cut-off | 180V | 5 | - | - | - |
Application Notes
Especially designed to minimize audio-frequency disturbances. Used in audio-frequency voltage amplifiers with volume control via grid bias adjustment and RF voltage amplifiers.
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