6DG7

The 6DG7 is a nine-pin miniature remote-cutoff pentode intended for radio-frequency and intermediate-frequency amplification. CIFTE's sheet emphasizes gain-controlled car-radio stages, high transconductance and very low control-grid-to-plate capacitance: the stated maximum without external shielding is 0.0018 pF. The document is marked as tentative data and cites JETEC registration release No. 1966 of July 1, 1957, sponsored by Compagnie des Lampes. This date documents the registration reference rather than establishing the start of commercial production.

The cathode is indirectly heated, with a 6.3 V, 0.3 A heater. The noval base uses connection 9BA: internal shield on pins 1 and 6, control grid on 2, cathode on 3, heater on 4 and 5, plate on 7, screen grid on 8 and suppressor grid on 9. The suppressor therefore has its own terminal; for the sheet's typical conditions it connects to the cathode at the socket. With 250 V plate voltage, 100 V screen voltage and a 68 Ω cathode resistor, the figures are 11 mA plate current, 4.2 mA screen current, 4.4 mA/V transconductance and approximately 1 MΩ plate resistance.

Remote-cutoff behavior also appears in the bias figure: about −20 V on the control grid brings transconductance to 40 µA/V under the stated conditions. The curves show current and transconductance varying with bias and screen voltage, illustrating gain control. Tentative Design Center limits distinguish 300 V plate voltage, 125 V at the screen grid and 300 V for its supply; the last figure is not the permitted voltage directly at that electrode. Other limits are 3 W plate dissipation, 0.6 W screen dissipation and 90 V peak heater-to-cathode voltage in either polarity. Documentary source: CIFTE 6DG7 tentative sheet with four pages of characteristic curves.