Tube-number record
20SP4
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BrandRCA
ClassPicture Tube
BaseCRT base (B7 family)
Filament6.3 V @ 450 mA
Construction
Primary TypeOther / special
EnvelopeFilterglass
Base MaterialNeo-eightar
Sections1
Filament / Heater
Heater NotesHeater Warm-Up Time (Average): 11 seconds
Absolute Maximum Ratings
Grid 2 Voltage60 V
H-C Voltage450 V
Audio Performance
Key Features
- Pan-o-Ply Type
- Low Grid-No.2 Voltage
- No Ion-Trap Magnet required
- Implosion Protection
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Cathode-Drive Service | 16000 V | — | — | — | — |
Application Notes
The grid-No.4 voltage required for optimum focus will have a value between -100 and +300 volts.
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