6N17B

The 6N17B, a transliteration of the Soviet 6Н17Б, is a subminiature double triode intended for low-frequency voltage amplification. Its glass bulb encloses two indirectly heated oxide-cathode systems; eight flexible wires connect it to the circuit. The documentation specifies operation in any position, a maximum weight of 4 g and a 6.3 V, 400 ±40 mA heater. Lead 1 is the second triode’s anode, 2 the first cathode, 3 its grid, 4 and 8 the heater, 5 the first anode, 6 the second cathode and 7 its grid.

The stated nominal point uses a 200 V anode supply and a 325 Ω cathode resistor for self-bias. For each triode the bilingual sheet specifies 3.3 ±1 mA anode current, 3.8 ±1 mA/V transconductance and an amplification factor of 75 ±15. This high amplification factor characterizes the triode; actual stage gain also depends on the circuit. The documentation includes families of anode curves, control characteristics and the variation of transconductance, amplification factor and internal resistance with current. It also presents pulse curves at 1 kHz with 2 µs pulses, distinct from continuous operation.

The stated limits include a 5.7–6.9 V heater supply, 250 V anode voltage, 0.9 W anode dissipation and 10 mA cathode current. Anode voltage of 350 V is allowed only at cutoff with current below 5 µA. The cathode–heater potential difference is limited to ±150 V and bulb temperature to 170 °C. Grid-circuit resistance may reach 1 MΩ; 2 MΩ is allowed only with self-bias and anode dissipation no greater than 0.6 W. These boundary values do not form a single operating point to be applied simultaneously.

A notable feature of the bilingual sheet is its declared ambient range of −70 to +200 °C, with relative humidity of 95–98% at +50 °C; the bulb-temperature limit remains separate. It states resistance to linear loads up to 100 g, vibration of 10 g, repeated impacts of 10 g and a single impact of 500 g. The same sheet guarantees 750 service hours, whereas another archived technical table gives at least 500 hours and describes leads at least 30 mm long and 0.4 mm in diameter. Both life figures retain their respective documentary provenance; they are not a universal prediction of tube life in a circuit.