Tube-number record
UD4I
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BrandMazda
ClassRectifier
Base7-pin (non-miniature)
Filament4 V @ 1150 mA
Construction
Primary TypeIndirectly heated
Rectifier TypeVoltage Doubler
EnvelopeGlass
SectionsDouble diode
Filament / Heater
Heater NotesIndirectly heated; suitable heating time for CRT protection
Absolute Maximum Ratings
Plate Voltage550 V
Cathode Current35 mA
Audio Performance
Key Features
- Designed for television scanning time bases
- Indirectly heated
- Voltage doubling capability
- Standard 7-pin base
- Safeguards CRT screen from stationary spots
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Voltage Doubling C1=2uF, C2=2uF, Vo=1240V | 500 V | — | — | — | 20 mA |
| Voltage Doubling C1=2uF, C2=4uF, Vo=1240V | 500 V | — | — | — | 20 mA |
| Voltage Doubling C1=2uF, C2=2uF, Vo=1320V | 550 V | — | — | — |
Application Notes
The UD4I is specifically designed for use in H.T. supply units for television time bases. Due to its heating time, it obviates the need for delayed switching in electrostatic tubes and protects the screen from burning by ensuring the time base is active before full H.T. is applied.
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