EF805S

Small Signal Pentode — Noval

Telefunken

Known Equivalents & Substitutes

EF85EF8656BY7

Similar Tubes (Not Drop-In Compatible)

19BY7

Brans Vademecum lists as equivalent. Same B9A base and similar characteristics but 19V series-string heater — not a drop-in in 6.3V heater circuits

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Ua max250V

Screen Voltage (max)Ug2 max250V

Anode Dissipation (max)Na2W

Screen Dissipation (max)Ng20.5W

Cathode Current (max)Ik16mA

Heater-to-Cathode Voltage (max)Uf/k100V

Max Grid ResistorRg1 (auto bias)3MΩ

Typical Operating

Anode Voltage (typical)Ua200V

Screen Voltage (typical)Ug2200V

Grid 1 Bias VoltageUg1-1.5V

Anode CurrentIa10mA

Screen CurrentIg22.5

Capacitances

Grid-to-Plate CapacitanceCg1a0.007pF

Grid-to-Cathode CapacitanceCg1f0.1pF

Input CapacitanceCe7.7pF

Output CapacitanceCa3.7pF

other

RkRk120Ω

Ua0 max (no current)Ua0 max (no current)550V

Ug20 max (no current)Ug20 max (no current)550V

Rg2 minRg2 min45kΩ

Heater

Heater VoltageUf6.3V

Heater CurrentIf0.285A

Notes

Long-life tube: guaranteed 10,000 hours averaged over 100 tubes, provided heater voltage is kept within ±5%
Heater current differs between manufacturers: Telefunken specifies 285 mA, AEG specifies 300 mA
Pin 1 is internally connected to pin 3 (both cathode)
Rg1 max is 3 MΩ for automatic (cathode) bias, reduced to 1.5 MΩ for fixed bias
Free socket contacts must not be used for supporting any circuitry
EF85 is the standard-life equivalent but may differ slightly in heater current and max cathode current ratings

Pin Layout — Noval

1Cathode (connected to pin 3)

2Control Grid

3Cathode (connected to pin 1)

References