Tube-number record
EFF 50
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BrandPhilips Miniwatt
ClassTwin H.F. Pentode
Filament6.3 V @ 0.6 mA
Construction
Primary TypePentode
EnvelopeGlass
SectionsTwin
Filament / Heater
Heater NotesIndirect heating, parallel supply
Absolute Maximum Ratings
Plate Voltage300 V
Plate Dissipation3 W
Grid 2 Voltage225 V
Grid 1 Voltage-1.3 V
Cathode Current15 mA
H-C Voltage50 V
Audio Performance
Key Features
- Ultra shortwave amplification
- Push-pull connection capability
- Wideband amplification capability
- Parallel connection capability
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Single section operation (Case 1) | 250 V | 8000 | 350000 | — | 6 mA |
| Single section operation (Case 2) | 300 V | 10000 | 250000 | — | 10 mA |
Application Notes
With push-pull operation, a separate dropping resistance should be used for each screen-grid to compensate for inequalities between systems. Grid damping is improved by inserting a 0.1 µH induction in each screen-grid lead.
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