Tube-number record
BI20
0 archive entries
BI20 is a tube type in the TubeDatabase archive (class: Low Voltage X-Ray Tube). Recorded specifications: brand Ferranti, year 1957, construction X-Ray Tube, socket Octal, maximum plate voltage 25000 V, and maximum plate dissipation 25 W. The archive does not yet hold a photographed example of this type.
BrandFerranti
ClassLow Voltage X-Ray Tube
BaseOctal
Construction
Primary TypeX-Ray Tube
EnvelopeGlass with thin window
SectionsSingle
Filament / Heater
MaterialTungsten
Absolute Maximum Ratings
Plate Voltage25000 V
Plate Dissipation25 W
Grid 1 Voltage-1400 V
Audio Performance
Key Features
- Copper target
- Thin glass window for low absorption
- Directly heated tungsten filament
- Control electrode for focus adjustment
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| DC Operation with Grid Bias | 20000 V | — | — | — | — |
| DC Operation with Auto Bias | 15000 V | — | — | — | 1.5 mA |
| AC Operation with Auto Bias | 15000 V | — | — | — |
Application Notes
Suitable for radiographic work on materials transparent to low voltage X-rays like plastics and thin metals. Radiation emitted through a thin glass window.
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