DK962

The DK962 is a heptode for mixer amplification and frequency conversion, within the battery-receiver context documented in the archive. RFT’s sheet from VEB Röhrenwerk Anna Seghers at Neuhaus am Rennweg specifies direct heating at 1.2 V, 60 mA. The edition is dated December 1956: this dates the available document, not independently the tube’s introduction. Similar names do not justify transferring filament currents or operating conditions from other heptodes.

The stated operating point has plate, g2 and g4 at 67.5 V and signal grid g3 at zero. Plate current is 1.2 mA, combined g2/g4 current 3.7 mA and conversion transconductance 0.29 mA/V. Oscillator grid g1 has a 70 kΩ grid-leak resistor and 120 µA current. Conversion transconductance concerns signal mixing, not audio-stage voltage gain. The sheet also states that figures printed in light type and not marked as limits are approximate.

Maximum values are plate voltage 90 V, plate dissipation 0.2 W, g2/g4 voltage 67.5 V, cathode current 6 mA and g3 grid-leak resistance 3 MΩ. Grid dissipations remain separate: g2 0.25 W, g4 0.05 W. Capacitances are input at g3 6.8 pF, output 5.2 pF and g3-to-plate less than 0.45 pF. “Less than” is part of the specification and is not replaced by an exact nominal value.

A seven-contact miniature base is used, classified B7G by archive information. RFT labels functions without pin numbers: plate, g1, g2, g3, g4, negative filament and positive filament together with g5. Thus g5 joins the positive as explicitly drawn, not by analogy. Maximum dimensions are bulb diameter 19 mm, body height excluding pins 47.6 mm and pin projection 7 mm. They are not summed to invent an unstated overall length. Stated weight is approximately 8 g, retaining that qualification in the structured records.

A practical detail is nominal size 38 under DIN 41537. The sheet names Gebr. Kleimann of Berlin-Lichtenberg for screening and mounting accessories of that size. This is the accessory supplier, not the DK962 manufacturer, identified as Röhrenwerk Anna Seghers. A reference to general operating conditions does not justify adding instructions absent from these two pages. Documentation: RFT, VEB Röhrenwerk Anna Seghers, DK962, Heptode für Mischverstärkung, December 1956 edition, two pages.