Tube-number record
E702A/E702E
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BrandEnglish Electric Valve Company Ltd
ClassDirect View Storage Tube
Base31-pin button
Filament6.3 V @ 600 mA
Construction
Primary TypeDisplay / CRT
EnvelopeGlass
SectionsTwo electron guns (Writing and Flood)
Filament / Heater
Heater NotesIndirectly heated oxide coated cathodes for both guns.
Absolute Maximum Ratings
Plate Voltage12000 V
Grid 2 Voltage250 V
Grid 1 Voltage200 V
Cathode Current2 mA
H-C Voltage125 V
Audio Performance
Key Features
- Direct view storage
- Useful viewing screen diameter of 4 inches
- Electrostatic deflection and focus
- High stored writing speeds
- Two electron gun construction
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Writing Gun | -2300 V | — | — | — | 0.55 mA |
| Flood Gun | 8000 V | — | — | — | 1.5 mA |
Application Notes
The E702E is selected for improved uniformity of erasure. Magnetic shielding is essential due to the low voltage of the flood gun beam. The tube should be transported screen upwards to prevent particles falling on storage elements.
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