Tube-number record
U.404
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U.404 is a tube type in the TubeDatabase archive (class: Half Wave Rectifier). Recorded specifications: brand Mazda, year 1948, construction Vacuum Tube, socket Special / none, and maximum plate voltage 250 V. The archive does not yet hold a photographed example of this type.
BrandMazda
ClassHalf Wave Rectifier
BaseSpecial / none
Filament40 V @ 100 mA
Construction
Primary TypeVacuum Tube
Rectifier TypeHalf-wave
EnvelopeClear
Sections1
Filament / Heater
Heater NotesIndirectly heated — for series operation
Absolute Maximum Ratings
Plate Voltage250 V
Cathode Current99 mA
H-C Voltage550 V
Audio Performance
Key Features
- Indirectly heated
- Series operation
- Unrestricted mounting position
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| 70mA load current | 230 V | — | — | — | 70 mA |
| 90mA load current | 230 V | — | — | — | 90 mA |
Application Notes
The 'Internal Connexion' pins are used for mechanical rigidity and must not be connected to the circuit.
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