Tube-number record
ECH 81
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BrandPhilips
ClassTriode-Heptode
BaseNoval (B9A)
Filament6.3 V @ 300 mA
Construction
Primary TypeMulti-section
EnvelopeGlass
SectionsDouble
Filament / Heater
Heater NotesIndirect heating; A.C. or D.C.; series or parallel supply
Absolute Maximum Ratings
Plate Voltage300 V
Plate Dissipation1.7 W
Grid 2 Voltage125 V
Grid 1 Voltage-1.3 V
Cathode Current12.5 mA
H-C Voltage150 V
Audio Performance
Power Output0.05 W
Key Features
- Indirectly heated
- Low microphonic effect
- Multi-purpose AM/FM mixer
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Heptode as Mixer | 250 V | 750 | 1000000 | — | 3 mA |
| Heptode as RF/IF Amplifier | 250 V | 2400 | 700000 | — | 6.5 mA |
| Triode section (Typical) | 100 V | 3700 | — | 22 | 13.5 mA |
Application Notes
Heptode section can be used without special precautions against microphonic effect in circuits where input voltage is >= 50mV for 50mW output.
Datasheets
Datasheet: ECH81.pdf
Download PDFLoading datasheet...
Datasheets courtesy of Frank Philipse via Frank's Electron Tube Data Sheets.
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