Tube-number record
HK-257B
0 archive entries
HK-257B is a tube type in the TubeDatabase archive (class: Beam Pentode). Recorded specifications: brand Heintz and Kaufman, construction Beam tetrode / beam power, base Giant 7-pin Bayonet, socket 7-pin (non-miniature), maximum plate voltage 4000 V, and maximum plate dissipation 75 W. The archive does not yet hold a photographed example of this type.
BrandHeintz and Kaufman
ClassBeam Pentode
Base7-pin (non-miniature)
Construction
Primary TypeBeam tetrode / beam power
EnvelopeNonex Glass
Base MaterialGiant 7-pin Bayonet
SectionsSingle
Filament / Heater
MaterialThoriated Tungsten
Absolute Maximum Ratings
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Radio Frequency Power Amplifier Class C Unmodulated | 3000 V | — | — | — | 100 mA |
| Radio Frequency Power Amplifier Class C Plate Modulated | 2500 V | — | — | — | 100 mA |
| Class A Amplifier Audio | 1000 V | — | — | — |
Application Notes
Always provide sufficient fixed bias or cathode bias to limit the plate current. Plate current depends on screen voltage. Apply screen voltage or excitation after or at the same time as plate voltage. Output and input circuits must be completely separated to prevent self-oscillation.
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