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Tube Substitutions for:
 4D21
 Power Tetrode
TypeSubstitutesBase Diagram
4D214-125A, 4D21A, 61555BK


Type 4D21
Power Tetrode


MECHANICAL DATA
Basing5BK


ELECTRICAL DATA

HEATER CHARACTERISTICS
Heater Voltage5Volts
Heater Current6.5A


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