ECC803

The ECC803 described in the JJ Electronic sheet is an audio-frequency twin triode with separate cathodes and a high amplification factor. The manufacturer describes it as non-microphonic, but this document gives no microphonics measurement or test procedure. It provides resistance-coupled amplifier examples and curves for both main operating relationships: plate current versus grid voltage and versus plate voltage. These data concern the JJ version documented here.

Typical characteristics refer to 250 V plate voltage and a 1.6 kΩ cathode resistor: plate current is 1.2 mA, transconductance 1.6 mA/V, internal resistance 62.5 kΩ and amplification factor 100. The heater requires approximately 300 mA at 6.3 V or 150 mA at 12.6 V. The noval base assigns plate, grid and cathode to pin groups 1–2–3 and 6–7–8; pins 4 and 5 are the heater ends, while 9 is the centre tap. Drawings specify maximum dimensions of 22.2 mm diameter, 49.2 mm envelope height and 56.3 mm overall height.

The JJ sheet gives limits of 330 V plate voltage, 1.2 W plate dissipation, 9 mA cathode current, 2.2 MΩ grid resistance and 200 V between cathode and heater; it also lists a negative grid-voltage limit of −55 V. Grid-to-cathode and grid-to-plate capacitances are respectively 1.6 and 1.7 pF for each system. Plate capacitance is specified separately: 0.46 pF for the first system and 0.34 pF for the second. Thus even in a twin tube, the capacitances of both sections need not be summarized by a single value.

The resistance-coupled amplifier table keeps the supply at 250 V and proposes three plate loads: 47, 100 and 220 kΩ. Associated plate currents are 1.18, 0.86 and 0.48 mA, with cathode resistors of 1.2, 1.5 and 2.7 kΩ; specified grid resistance is 1 MΩ in all three cases. Supply voltage is upstream of the plate load and must be distinguished from actual plate voltage. The document finally mentions the 6057 as a replaceable type, without developing the comparison: this reference adds no operating conditions or guarantees beyond those stated in the sheet.