Tube-number record
7504S
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7504S is a tube type in the TubeDatabase archive (class: Decade Selector and Counting Tube). Recorded specifications: brand Mullard, construction Other / special, socket CRT / special base, and maximum plate voltage 550 V. The archive does not yet hold a photographed example of this type.
BrandMullard
ClassDecade Selector and Counting Tube
BaseCRT / special base
Construction
Primary TypeOther / special
EnvelopeGlass
Sections10 main cathodes
Filament / Heater
Absolute Maximum Ratings
Plate Voltage550 V
Grid 1 Voltage-20 V
Cathode Current0.525 mA
Audio Performance
Key Features
- Short all-glass
- Neon-type glow
- Bidirectional counting
- High mechanical tolerances
Typical Operation
| Mode | Plate V | Gm (µmhos) | Rp (Ω) | µ | Plate mA |
|---|---|---|---|---|---|
| Recommended Double Pulse Drive | 475 V | — | — | — | 0.34 mA |
Application Notes
Unused cathodes should be connected together and returned to zero voltage. All voltages are referred to the most positive supply potential to which any main cathode is returned.
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