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Tube Database (7,341 tube types · 1,270 archive entries)

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DF 21 vacuum tube outline illustration

Tube-number record

DF 21

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DF 21 is a tube type in the TubeDatabase archive (class: Pentode). Recorded specifications: brand Philips, construction Pentode, socket Loctal, maximum plate voltage 135 V, and maximum plate dissipation 0.2 W. The archive does not yet hold a photographed example of this type.

BrandPhilips
ClassPentode
BaseLoctal

Construction

Primary TypePentode
EnvelopeGlass
SectionsSingle

Filament / Heater

MaterialDirectly Heated

Absolute Maximum Ratings

Plate Voltage135 V

Typical Operation

ModePlate VGm (µmhos)Rp (Ω)µPlate mA
H.F. / M.F. Amplifier90 V7002000000301.2 mA
L.F. Amplifier120 V—1000000850.28 mA

Application Notes

The DF 21 is a battery pentode designed for low current consumption. It can be used in H.F. and M.F. stages with AGC, or as an L.F. resistance-coupled amplifier where it can achieve a gain of up to 85.

Datasheets

Datasheet: DF21.pdf

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Datasheets courtesy of Frank Philipse via Frank's Electron Tube Data Sheets.

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    Plate Dissipation
    0.2 W
    Grid 2 Voltage135 V
    Grid 1 Voltage-0.2 V
    Cathode Current2.5 mA

    Audio Performance

    Typical THD0.75%
    Key Features
    • Low filament current (25 mA)
    • Suitable for H.F., M.F. and L.F. amplification
    • Directly heated
    • Parallel or series filament supply