X719 / ECH81
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BrandMarconi
ClassTriode-Heptode
BaseB9A
Filament6.3V @ 300mA
Construction
Primary TypeIndirectly Heated
EnvelopeTubular
SectionsTriode-Heptode
Filament / Heater
Heater NotesIndirectly heated
Absolute Maximum Ratings
Plate Voltage300 V
Plate Dissipation1.7 W
Grid 2 Voltage300 V
Grid 1 Voltage-1.3 V
Cathode Current12.5 mA
H-C Voltage100 V
Audio Performance
Key Features
- Indirectly heated
- Frequency changer
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Triode Section | 100V | 3700 | - | 22 | 13.5mA |
| Heptode Section as r.f. or i.f. Amplifier | 250V | 2400 | 700000 | - | 6.5mA |
| Heptode Section as a.m. Frequency Changer | 250V | 775 | 1000000 | - | 3.25mA |
Application Notes
Primarily designed for use as a frequency changer. Rg1-k is 3 megohms.
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