Western Electric equivalent — electrically identical per STC datasheet, but uses Magnoval (B9D) base instead of Loctal (B8G). Not pin-compatible.
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Max DC Plate Voltage350V
Anode Dissipation (max)Max Plate Dissipation7W
Cathode Current (max)Max DC Plate Current45mA
Typical Operating
Anode Voltage (typical)Plate Voltage150V
Notes
Manufactured by STC (an ITT associate company) in the UK. Designed for wide band repeater amplifier service in coaxial carrier telephone systems.
Also found use in high-quality audio applications, particularly as a cathode follower stage for matching condenser microphones to low-impedance mixing desk inputs.
Uses Loctal (B8G) 8-pin base. Pins 2 and 6 are internal connections; pin 3 is no connection.
Typical operating point: Va = 150 V, Vg = -1.5 V, Ia = 40 mA. At this point gm = 47 mA/V, ra = 1000 ohms.
The STC datasheet states this tube is identical with the American type 437A.
Pin Layout — Loctal
1Heater
2Internal Connection
3No Connection
4
Socket-Compatible Tubes ⚠ Not electrically compatible