6CM4

6CM4 has no equivalent designation confirmed by the archive.

Description

The 6CM4 is a vacuum tube employing a coated unipotential cathode. It has a T 6 1/2 bulb and a 9-pin E 9-1 base, with a maximum diameter of 7/8 inch, a maximum overall length of 2-3/16 inches, and a maximum seated height of 1-15/16 inches. It uses Basing 946.

Construction and Mounting

Pin connections are: pin 1 plate, pin 2 grid, pin 3 cathode, pin 4 heater, pin 5 heater, pin 6 grid, pin 7 cathode, pin 8 grid, and pin 9 plate. The tube can be mounted in any position.

Ratings

The heater is rated at 6.3 volts with a heater current of 170 mA. Maximum heater-cathode voltage is 100 volts, either polarity, and maximum cathode-heater resistance is 20,000 ohms. Maximum plate voltage is 220 volts, maximum plate dissipation is 2.2 watts, and maximum cathode current is 20 mA. Maximum grid circuit resistance is 1.0 megohm, and maximum negative grid voltage is 50 volts. The maximum frequency for UHF amplification is 800 Mc.

Electrical Characteristics

At a plate voltage of 175 volts and a grid voltage of -1.5 volts, plate current is 12 mA. Under these conditions, transconductance is 14,000 μmhos, amplification factor is 68, and equivalent noise resistance is 230 ohms. Space-charge capacitance (grounded cathode) is 2.0 μμf, the phase of transconductance is -7 degrees, and additional grid-noise-conductance is 0.5 mmhos.

Capacitance

The datasheet gives grid-to-plate capacitance as 3.1 μμf with shield and 2.0 μμf without shield. Without shield, plate-to-grid-and-heater capacitance is 2.1 μμf, plate-to-cathode capacitance is 0.2 μμf, grid-to-cathode capacitance is 3.6 μμf, cathode-to-grid-and-heater capacitance is 6.6 μμf, and grid-to-heater capacitance is less than 0.3 μμf. Grid-to-cathode-and-heater capacitance is 4.2 μμf with shield and 3.9 μμf without shield; plate-to-cathode-and-heater capacitance is 0.25 μμf with shield and 0.3 μμf without shield. The external shield specified is 15/16 inch in diameter and 2 inches in length.

Base B9A, viewed from below (the wiring side), pins numbered clockwise from the key. Read from the datasheet's basing table and checked against it automatically — confirm against the original datasheet before wiring.

Original manufacturer datasheets for 6CM4, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• Typical operating conditions and characteristics, grounded-grid amplifier

1 further designation appears alongside 6CM4 in the literature but below the evidence threshold used here, so it is not listed as equivalent.