Section VI. POWER SUPPLIES AND MINOR COMPONENTS

d. The outputs of the 10-position, 1.0-mc

coils to be tuned from 20.0 to 29.9 mc.

and 0.1-mc automatic positioners are

0.1-mc steps.

combined through a gear train to control

e. The outputs of all three automatic

the rotation of a second tuning shaft within

positioners are combined by a gear train to

the first if. amplifier. This shaft is coupled

to the tuning coils of if. coil assemblies

control the rotation of the tuning shaft with-

in the rf and power amplifier subunit. Par-

2301 through 2306 (fig. 8). Because the

allel-tuned tank circuits Z101, Z103, Z105,

.1-mc automatic positioner turns 10 times

Z106, and Z107 and cavity resonator Z108

for each revolution of the 1.0-mc automatic

(fig. 5 and 19) are tuned from 399.9 to

positioner, the turning shaft can be ac-

225.0 mc, in 0.1-mc steps, by the rotation

curately turned to 100 positions in incre-

of the 1,800-position tuning shaft.

ments of 0.1-mc, which enables the tuning

Section VI. POWER SUPPLIES AND MINOR COMPONENTS

blower. Fuse F1802 protects the pri-

87. Power Supply PP-1494/U

mary windings of transformer T1801;

(fig. 29)

it is either a 1-1/2- or 3-ampere fuse,

Power Supply PP-1494/U operates on

depending on whether the operating voltage

115/230 volts ac, 50/60 cps, and supplies

is 230 or 115 volts ac. Fuse F1803 pro-

operating voltages for Receiver-Trans-

tects the primary windings of trans-

miter RT-441/TRC-68.

former T1802 and is either a 3/4- or a

1-1/2-ampere fuse.

a. Ac power is applied to power supply

c. A full-wave rectifier, which con-

input terminals 13 and 14 of plug 1801.

sists of diodes CR1801, CR1802, CR1803

When the ac power source voltage is 115

and CR1804, is connected across sec

volts switch S1803 is positioned as shown,

ondary winding terminals 5 and 6 of

and 115 volts ac is applied across the pri-

transformer T1801. This circuit pro-

mary windings (1-2 and 3-4) of trans-

vides +300 volts dc for the transmitter

former T1803 in parallel. When S1803

tubes and is protected by fuse F1806.

switch is in the 230-volt position, the pri-

Filtering is provided by reactors L1801

mary windings are in series and 115 volts

and L1802 and capacitor C1801. Capac-

ac is applied across each winding. Switches

itor C1802 is an additional filter in the

S1801 and S1802 perform the same function

+300-volt line. Diode CR1817, connected

for T1801 and T1802. The primary of T1803

across L1802, is a transient suppressor,

is connected to the ac power cord at all

and resistors R1801, R1802, R1804, and

times.

R1805 are bleeder resistors to ground.

d. A full-wave rectifier, which con-

b. Fuse F1801 is either 3- or 5-ampere,

depending on whether the source voltage is

sists of diodes CR1805, CR1806, CR1807,

230 or 115 volts ac. Fuse F1804 protects

and CR1808, is connected across sec-

the primary winding of transformer T1803.

ondary terminals 7 and 8 of transformer

A full-wave rectifier circuit, which con-

T1801. This circuit provides +26.4 volts

sists of diodes CR1813, CR1814, CR1815,

dc for the RT-441/TRC-68 and is protected

and CR1816, rectifies the output of trans-

by fuse F1805. When this voltage is sup-

former T1803 and applies +26.7 volts

plied, POWER indicator lamp I1801 lights.

across relay K1081. When relay K1801

e. Ac filament voltage is supplied to the

RT-441/TRC-68 from secondary taps 8, 9,

is energized (para 81), contacts B1 and

B2 and A1 and A2 close and the ac power

10, and 11 of transformer T1802. Full

source is applied to the primary wind-

wave rectifier, CR1809, CR1810, CR1811

ings of transformers T1801 and T1802.

and CR1812, is connected across trans-

Contacts D1 and D2 of K1801 close

former T1802 secondary terminals 5 and

and complete the ac circuit to the case

This circuit provides 115 volts dc across