Tube-number record
7J7
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BrandSylvania
ClassTriode-Hexode Converter
BaseLoctal
Filament7 V @ 0.3 mA
Construction
Primary TypeMulti-section
EnvelopeT9-G
Base MaterialLoktal
SectionsDual
Filament / Heater
Heater Notes7.0V nominal; 6.3V typical operation
Absolute Maximum Ratings
Plate Voltage250 V
Grid 2 Voltage100 V
Audio Performance
Key Features
- Low frequency drift
- Loktal base
- Common cathode
- Electronic coupling
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Converter (Hexode Section) | 250 V | 310 | 1500000 | — | 1.4 mA |
| Triode Section Only | 150 V | 1350 | 10400 | 14 | 7.5 mA |
| Oscillator Section | 250 V | — | — |
Application Notes
The 7J7 is a loktal converter composed of a triode and hexode section. It features higher frequency stability compared to other converters, reducing the need for extensive plate filtering. Grid-screen dropping resistors can be eliminated if both sections run at 100V.
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