Western electric 421 a brochure

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BELL SYSTEM PRACTICES SECTION ABA6.h21A
Transmission Engineering and Data Issue 2, October 1953
Electron Tube Data A.T.& T.Co. Standard

ELECTRON TUBE DATA SHEET
WESTERN ELECTRIC 42lA* ELECTRON TUBE

DESCRIPTION

The 5998/L21A* is a double triode having separate indirectly heated cathodes.

It is intended for use as a series tube in regulated rectifier circuits.

CHARACTERISTICS

Heater Voltage -------------------- 6.3 volts

Plate Current per Section { Ebb - 110 volts;} - - - 125 milliamperes
Transconductance per Section Rk - 65 ohms - - - 20000 micromhos

FILE: GENERAL PURPOSE SECTION
Issue 2, 10-53

42IA*

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5998/L21A » PAGE 2

GENERAL CHARACTERISTICS
ELECTRICAL DATA

Heater Voltage ---------------------- 6,3 volts
Heater Current --------------------- 3-5 amperes

HECHAfiICAL DATA

Cathode ---------------------- Coated Unipotential
Bulb ------------------------ ST 16
Base ------------------------ Hedium 8-pin octel
Mounting Position ----------------- Any
Dimensions and Pin Connections -------- See Outline drawing page L
MAXIMUM RATIKGS, Design-Center Values (Each Tricde)
Plate Voltage ------------------- 250 volts
Plate Dissipation ----------------- 13 watts
Cathode Current ------------------ 1&5 milliamperes
Heater-Cathode Voltagel -------------- 150 volts
Bulb Tenpareturel ----------------- 200°Centigrade
Haximum Grid Circuit Resistance for Cathode Bias - - 0.1 megohn
OPERATING CCNDITICNS AfiD GEARACTERISTICS (Each Triode)
Plate Supply Voltage ----- - ------- 110 110 volts
Cathode Bias Resistance ----------- 90 65 ohms
Plate Current ---------------- 100 125 milliamperes
Amplification Factor ------------- 5.9 6.1
Plate Resistance --------------- 330 305 ohms
Transconductance --------------- 18000 20000 nicronhos

Note 1: For optimum life expectancy the heater-cathode voltage should not
exceed 90 volts and forced-air cooling should be provided= The air
flow should be sufficient to keep the bulb temperature below 150°C