Tube-number record
QP 240
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QP 240 is a tube type in the TubeDatabase archive (class: Battery Double Pentode Output Valve). Recorded specifications: brand Mazda, construction Pentode, socket Noval (B9A), and maximum plate voltage 150 V. The archive does not yet hold a photographed example of this type.
BrandMazda
ClassBattery Double Pentode Output Valve
BaseNoval (B9A)
Construction
Primary TypePentode
EnvelopeGlass
SectionsDouble
Filament / Heater
Absolute Maximum Ratings
Plate Voltage150 V
Grid 2 Voltage150 V
Audio Performance
Key Features
- Quiescent Push-pull
- Individually matched sections
- Battery receivers
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Quiescent Push-Pull | 100 V | 4000 | — | — | — |
| Quiescent Push-Pull | 135 V | — | 16000 | — | 3.3 mA |
Application Notes
All symmetrical push-pull circuits are liable to generate parasitic oscillation. This can be avoided by connecting resistances up to 50,000 ohms in series with the pentode grids close to the valve pins or, alternatively, by connecting condensers 0.001 mf. capacity between the anodes and filament.
Datasheets
Datasheet: QP240.pdf
Download PDFLoading datasheet...
Datasheets courtesy of Frank Philipse via Frank's Electron Tube Data Sheets.
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