d. Power Transformer and Power Rec-
e. Series Regulator, Regulator Control,
tifier (fig. 3). Power transformer T1 con-
and Voltage Reference. The electronic
tains two primary windings, three second-
voltage regulator consists of series reg-
ary filament windings, and a center-tapped
ulator tube V5, regulator control tube V6,
high-voltage (hv) winding. Two primary
and voltage reference tube V7 (fig. 4).
--
windings are provided so that they can be
(1) The cathode voltage of V5 (+210)
connected in parallel for operation from
is held constant due to the action
115-volt alternating current (ac) lines or
of regulator control tube V6 and
in series for operation from 230-volt ac
voltage reference tube V7. A
lines (para 9, TM 11-6625-353-12). One
change in output voltage due to a
filament winding is used for regulator
change either in input (line) volt-
tubes V5 and V6. A second filament
age or in the load current is cor-
winding provides 5 volts to the filament
rected by automatic adjustment of
of V4. The third filament winding provides
the series regulator grid bias.
9 volts with a tap at 6.3 volts for lamp
(2) A sample of the output voltage is
DS1 and V3. The 9-volt portion is con-
obtained from R25 and R26 in
nected to full-wave bridge rectifier CR1
parallel and applied to the grid
to obtain dc filament voltage for V1 and
of V6. Regulator control V6 am-
V2. The dc filament voltage prevents
plifies any variation of the output
line-frequency modulation of the amplified
voltage by means of the voltage
signal. Resistor R27 provides adjustment
drop across R22, and applies it
of the dc level to compensate for any
directly to the control grid of V5.
change in resistance of CR1 as it ages.
The value of R25 is factory se-
Capacitor C7A with C7B filters the output
lected to adjust the output voltage
of CR1. The hv winding of T1 is connected
at +210 volts 5; it acts as a B+
to the plates of full-wave power rectifier
voltage-adjusting resistor.
(3) Voltage reference tube V7 pro-
V4. The rectified dc output is filtered by
C8A, C8B, and R21.
vides a stable fixed voltage of +150
Figure 3. Power transformer and power rectifier,
schematic diagram.
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