EF804

EF804 has no equivalent designation confirmed by the archive.

The EF804 is a low-noise and low-hum pentode for audio-frequency use (kling- und brummarme NF-Pentode).

Construction

The tube uses a Pico 9 (Noval) base. Its maximum weight is 17 g. The Telefunken datasheet specifies an input capacitance of 4.8 pF, an output capacitance of 6.0 pF, a grid 1 to anode capacitance of no more than 0.06 pF, and a grid 1 to heater capacitance of less than 0.002 pF.

Ratings

The heater is rated at 6.3 V and draws 200 mA. Maximum ratings include an anode cold voltage of 550 V, an anode voltage of 300 V, an anode dissipation of 1.5 W, a screen-grid cold voltage of 550 V, a screen-grid voltage of 200 V, a screen-grid dissipation of 0.2 W, and a cathode current of 6 mA. The maximum grid 1 resistor is 10 MΩ when anode dissipation is below 0.2 W, and 3 MΩ when anode dissipation is at least 0.2 W. The maximum voltage between heater and cathode is 100 V, and the maximum external resistance between heater and cathode is 20 kΩ. The maximum bulb temperature is 170 °C.

Characteristics

At an anode voltage of 250 V, a screen-grid voltage of 140 V, and a grid bias of -2 V, the anode current is 3 mA, the screen-grid current is 0.6 mA, the transconductance is 2.0 mA/V, the internal (anode) resistance is 2 MΩ, and the amplification factor (screen-grid to grid 1) is 38. The grid-current starting point (for grid current ≤ +0.3 µA) is -1.3 V.

Applications

The Telefunken datasheet states that the EF804 may be used without special measures against microphony and hum in power amplifiers where the maximum power is achieved with an effective input voltage of at least 5 mV, and in receivers where an output of 50 mW is achieved with an effective input voltage of at least 0.5 mV, provided the grid 1 resistor is at most 1 MΩ.

Original manufacturer datasheets for EF804, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• **TELEFUNKEN**