DD960

The DD960 is an RFT VHF triode, UKW in the VEB Röhrenwerk Anna Seghers sheet, not a double diode inferred from its name. Its centre-tapped filament allows halves in parallel at 1.2 V, 200 mA or series at 2.4 V, 100 mA. These primary values are not replaced by secondary 1.4/2.8 V. The provisional February 1956 edition declares earlier editions invalid.

Static data explicitly use parallel heating. Plate 100 V, grid −6.5 V: plate current 10 mA, transconductance 2.5 mA/V, internal resistance 3.3 kΩ. Plate 67.5 V, grid −3 V: 9 mA, 2.45 mA/V, 3.4 kΩ. Both have amplification factor 8.3 and Durchgriff 12%, electrostatic penetration rather than distortion. These points are not automatically transferred to series filament connection.

A specifically RF parameter is input resistance at 100 MHz: 5 kΩ at the first point, 4.5 kΩ at the second, not a DC grid resistor to install by analogy. Maxima: plate voltage 150 V, dissipation 1.8 W, current 18 mA. Maximum grid-leak resistance depends on dissipation: 1 MΩ up to and including 1 W, 0.5 MΩ above 1 W. Capacitances: input 1.1 pF, output 2.3 pF, grid-plate 6.2 pF, retained in source categories without inventing a measurement arrangement.

Seven-contact miniature base, B7G in archive data. Unnumbered drawing identifies grid, plate, filament ends, centre tap fM, i.V. internal connection and an unlabelled contact. Functions are retained without invented pin numbers or using an internal contact as tie point. Manufacturer forbids free socket contacts as wiring supports. Maximum bulb diameter 19 mm, body height excluding pin projection 47.6 mm; lower 7 mm separately dimensioned, not added to create unstated overall height. Weight approximately 7 g.

Standard size 38 under DIN 41537; Gebr. Kleimann, Berlin-Lichtenberg, is named for shielding and mounting accessories, not as another triode manufacturer. Values not marked as limits are approximate, relevant when comparing specimens. No curves or complete-amplifier output power are given. Documentation: RFT, VEB Röhrenwerk Anna Seghers, DD960, UKW-Triode, Vorläufige technische Daten, February 1956, two pages.