6N24P

The 6N24P, the transliterated designation of the Soviet 6Н24П, is a miniature twin triode for high-frequency voltage amplification in cascode circuits. In this configuration the two triodes work successively within the same stage. The sheet describes oxide cathodes and indirect heating, with a 6.3 V heater and nominal current of 300 mA, specifying a tolerance of ±25 mA. The glass envelope uses nine pins. Its particular arrangement is: second-triode cathode on pin 1, second-triode grid and internal shield on 2, second-triode plate on 3; heater on 4 and 5, first-triode grid on 6, first-triode cathode on 7 and 8, and first-triode plate on 9.

For each triode, the bilingual sheet gives nominal plate voltage of 100 V, a 680 Ω cathode resistor, plate current of 15 mA, transconductance of 12.5 ±2.5 mA/V and amplification factor 33 ±7. The table's 9 V value is the circuit grid voltage with cathode bias, to be read together with the 680 Ω resistor, not a recommendation to apply +9 V between grid and cathode. The Russian manual extract instead uses 90 V plate voltage for nominal data and presents three cascode conditions. In the first, with 120 V overall, 60 V at the first triode plate and its grid at −0.8 V, it gives approximately 8 mA and transconductance of 10.5 mA/V; at 200 MHz it specifies input resistance of 425 Ω and equivalent noise resistance of 375 Ω. These are data for that configuration, distinct from individual-section characteristics.

The bilingual sheet's limits include 300 V plate voltage, 470 V with the tube cut off, 1.8 W plate dissipation and maximum average cathode current of 20 mA. The heater permits 5.7 to 7 V; the cathode-to-heater voltage limit is 150 V, increased to 200 V at switch-on for no more than five minutes. The documentation also states resistance to ambient conditions from −60 to +70 °C, vibration up to 2.5 g and repeated impacts up to 12 g, together with a stated guaranteed service life of 1,000 hours: this is a source specification, not a prediction of the life of a present-day specimen. Curves show how transconductance, amplification factor and resistances vary with plate current. Documentation examined: 6Н24П, bilingual Russian/English sheet, pp. 56–57; Russian manual extract for 6Н24П, figures 372–373. The available copies identify no date or specific manufacturer.