6C4WA

The 6C4WA is a special-quality miniature triode in the 6C4 family, intended for applications where stability and reliability matter. Raytheon’s May 1, 1956 document uses the dual designation CK6100/6C4WA and describes a medium-mu triode suitable for class C amplifiers and oscillators. It is designed for high temperatures, shock and vibration; our sources also indicate mobile and aircraft equipment. Its distinctive feature is therefore performance control under demanding conditions alongside the small triode’s radio role.

Heating is indirect, nominally 6.3 V and 150 mA. The glass envelope has a seven-pin miniature base. For the CK6100/6C4WA Raytheon assigns anode to pins 1 and 5, grid 6, cathode 7 and heater 3 and 4; pin 2 is an internal connection. This detail of the specific document deserves attention when consulting pinouts. Any mounting position is allowed. Archived photographs show General Electric, Philips ECG and Sylvania examples, without implying identical acceptance specifications for all of them.

Raytheon normal test conditions are 250 V anode and −8.5 V grid: central anode current is 10.5 mA and transconductance 2200 µmho, or 2.2 mA/V. Central amplification factor is 17; without an external shield the central capacitances are grid–anode 1.6 pF, input 1.8 pF and output 1.3 pF. The table distinguishes another normal regime at 100 V anode and zero grid, giving 11.8 mA. Curves also trace anode current, grid current, internal resistance, transconductance and amplification factor: these values are not constant at every operating point.

Absolute maxima in the sheet are 330 V anode, 3.8 W anode dissipation, 20 mA anode current and 5.5 mA grid current; grid circuit resistance reaches 1.2 MΩ and heater–cathode voltage ±200 V. Bulb temperature must not exceed 165 °C. The 3.8 W dissipation is an anode thermal limit, not delivered RF power. Raytheon relates reliability to maintaining heating near nominal 6.3 V and notes possible difficulties during prolonged operation at very small cathode currents.

The most characteristic part is the acceptance program: insulation, noise and microphonics checks, 450 g shock and 2.5 g vibration tests, plus thermal cycling and life tests. Heater cycling reaches 20000 one-minute-on/one-minute-off cycles under specified test conditions; intermittent 500- and 1000-hour tests at 165 °C bulb temperature are also provided. These are sample tests with acceptance criteria, not a guarantee of identical life for every tube. This documentation explains the practical meaning of the 6C4WA’s special quality.