Raytheon data shows slightly different test conditions: Va=250V, Vg=-12.5V, Ia=3.5mA, gm=2800 umhos, ra=8500 ohms — these may reflect a different operating point.
Brans Vademecum groups 14A4 with 6C4, 6C4W, 6CW4, 6FQ5, 7E5, EC70, and other medium-mu single triodes.
Designed for series-string heater chains in AC/DC radio and television receivers.
Pin Layout — Loctal
1Heater
2Plate
3No Connection
4
Socket-Compatible Tubes ⚠ Not electrically compatible