Western electric 20 a schematic

Page 2

Wm Hermie Company
No.20-A RECTIFIERS

TYPE

Full-wave vacuum-tube rectifier incorporating a vacuum-tube voltage-regu-
lating circuit with provision for preventing the plate voltage from rising above
its final value during the warm-up period of the voltage-regulator tube.

TYPICAL CHARACTERISTICS

Input-100130 volts, 60 cycles, with transformer primary taps for nominal
line voltages 105, 115 or 125 volts. Power consumption approximately
55 W.-.7A at 125 volts for no load and 196W.-1.7A for rated load.

OutpuI-Rated load-plate supply 110 milliamperes at 275 volts d-c and
filament supply 10 amperes at 6.5 volts a-c.

Plate Supp/y Regulution-3 volts max. voltage change from no load and
+10 per cent line voltage to rated load and -10 per cent line voltage.

Plate Supp/y Ripple-Approximately 5 millivolts rms at rated load.

EQUIPMENT CHARACTERISTICS

Dimemium
Mat-193E x 6%; inches.

Chassis-Overall including mounting flanges, 18};'; x 6% x 2 inches.
Width of recessed section, 17 inches.
Maximum Depth of Apparatus-63A inches, from front edge of chassis.

Weigh-26 pounds.

Mounting-Recessed panel type designed to mount vertically on standard
relay rack or speech-input cabinet where it occupies 7 inches of panel
space. May also be mounted horizontally on a flat surface by moving
the power switch and potentiometer to either side wall of the chassis
utilizing knock-outs provided.

Mat Finish-Aluminum gray (20A-15 ReCtifier); black japan (20A-3 Rec-
tifier). Aluminum gray furnished unless otherwise specified.

Charm FiniIb-Bright aluminum enamel.

PROTECTION

A 2-ampere No. 902 Fustat which is furnished accessible from the rear of
the chassis provides protection in the power input circuit for rated output load
plus allowance for 10 per cent high line voltage. The Fustac socket is arranged
to prevent the use of higher amperage Fustats, but will accommodate one other

Instruction Bulletin No. 978

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