CV4011

The CV4011 is a miniature, sharp-cutoff, dual-control pentode intended for radio-frequency service with reliability requirements. Dual control means that both the control grid and the suppressor grid can be used to control the valve; applications in our sources include mixing and modulation. British specification MOS(A)/CV.4011, issue 2 of 26 February 1957, identifies the 5725/6AS6W as the prototype and incorporates US military specification MIL-E-1/6C of 25 July 1956. The document therefore describes a component subject to qualification and acceptance criteria as well as ordinary electrical specifications.

The cathode is indirectly heated, with a 6.3 V heater and nominal current of 0.175 A. The B7G base has seven pins: 1 control grid, 2 cathode and internal shield, 3 and 4 heater, 5 anode, 6 screen grid and 7 suppressor grid. This separate suppressor connection provides the second control input. Mounting is permitted in any position. The British sheet gives a maximum grid-to-anode capacitance of 0.02 pF and nominal input and output capacitances of 4 and 3 pF, measured with a metal screen or skirted holder.

The military specification sets a test point with 120 V at the anode, 120 V at the screen, −2 V at the control grid and 0 V at the suppressor: reference values are 5.2 mA anode current and 3.2 mA/V transconductance. These are test data, separate from the absolute limits of 200 V anode voltage and 155 V screen voltage. The MOS sheet also specifies a maximum suppressor voltage of 30 V, 1.65 W anode dissipation, 0.55 W screen dissipation, 20 mA cathode current and ±100 V between heater and cathode.

The most distinctive part of the documentation is its attention to demanding conditions: it includes vibration, shock, fatigue, noise and microphonics, insulation and heater cycling tests, as well as intermittent-life checks at 500 and 1,000 hours. These durations belong to acceptance procedures and do not promise a lifespan for each specimen. The British note expressly refers to aircraft equipment and sets a maximum bulb temperature of 140 °C, stressing heater regulation and compliance with thermal conditions. The 165 °C figure in the American specification must be kept separate from this British limit. Documentation: MOS(A)/CV.4011, issue 2, and MIL-E-1/6C for JAN-5725/6AS6W.