EC806S

The EC806S is a UHF triode presented by Telefunken together with E86C. It is documented as a grounded-grid RF amplifier and self-excited mixer. Electrical curves are accompanied by separate life, reliability, tolerance and mechanical-strength specifications. Indirect heating uses AC or DC parallel supply at 6.3 V, current 165 ±10 mA.

One measuring point uses anode supply 185 V, grid-circuit supply +8 V and cathode resistor 800 Ω: anode current 12 ±0.8 mA, transconductance 14 mA/V with +3/−2.5 tolerance, amplification factor 68. Another point uses actual anode voltage 175 V and cathode resistor 125 Ω, again 12 mA and 14 mA/V. Telefunken recommends the larger cathode resistor and positive grid-circuit supply for stability over life. The +8 V is a circuit supply, not a stated positive grid-cathode bias.

As a self-excited mixer, typical data give anode supply 220 V, capacitively bypassed anode resistor 5.6 kΩ, grid resistor 47 kΩ, approximately 12 mA anode current and 50 µA grid current. RF-amplifier data also give equivalent noise resistance 250 Ω and input resistance 2 kΩ at 100 MHz. Different definitions and conditions, not a universal circuit gain or sensitivity.

Telefunken states 10,000 hours life averaged over one hundred tubes, conditional on heater voltage within ±5%. Reliability factor P is approximately 1.5 failures per thousand tubes per thousand hours. End-of-life criteria referred to the specified measuring point are anode current fallen to 10.5 mA, transconductance to 9.5 mA/V, or negative grid current risen above 1 µA. These are historical specifications and statistical criteria, not measurements of a specimen preserved today.

The sheet describes tighter electrical tolerances than ordinary receiving tubes, prolonged vibration resistance of 2.5 g at 50 Hz and momentary shocks up to 500 g. A special cathode is said to prevent interface formation even with the heater on but no anode current for lengthy periods. Base contacts are gilded. These requirements describe the component without turning strength and mean life into a promise for every installation.

Absolute limits: operating anode 250 V, cold 440 V, anode dissipation 2.4 W, cathode current 20 mA, negative bias up to 50 V, grid dissipation 20 mW, grid resistance 1.2 MΩ with automatic bias, external heater-cathode resistance 20 kΩ. Heater-cathode insulation 100 V, bulb maximum 165 °C, RF-amplifier maximum frequency 800 MHz. Capacitances include grid-cathode 3.6 ±0.6 pF, anode-cathode 0.2 ±0.04 pF, grid-anode 2.0 ±0.3 pF, with another set measured using an external shield. The test cylinder with internal diameter 22.5 mm and length 49 mm is not the tube envelope.

Pico 9–Noval B9A: 1 and 9 anode, 2, 6 and 8 grid, 3 and 7 cathode, 4 and 5 heater. The Telefunken DIN 41539 form A outline gives maxima diameter 22.2 mm, body above terminals 49.2 mm, separately showing terminal length 7 mm; maximum mass 14 g. Where necessary the manufacturer requires retention against dislodging. The photo documents a Telefunken specimen, not dimensions measured from its image. Documentation: Telefunken EC806S–E86C, five pages of tentative data, reliability, life, RF operation, limits, capacitances, base, dimensions and curves; technical sheets dated September 1961 and January 1963; specimen photograph.