Power Supply Circuits

TM 11-6625-467-34

hertz range are therefore identical. Switch S7

is more complex, the switches provide a basic func-

selects one of the two codes by generating an am-

tion similar to S1 in the simple switching arrange-

biguity code. For the 30-megahertz range, switch

ment of figure 2-30. The test set switching circuits

S7A, section Z grounds megahertz ambiguity line A.

are described in b and c below.

Megahertz ambiguity line B is grounded when S7 is

b. 0.05 Megahertz Switching. Switch S9 selects

set to 50. The same general concept is true for posi-

fractional megahertz in steps of 0.05 megahertz.

tions 40 and 60 of switch S7. Switch S7 connects the

F i g u r e 2-32 shows the 0.05 megahertz selector

five lines from S8A and S8C to the megahertz select

switch connected to a typical drive circuit. Switch

lines A through E. Megahertz ambiguity line A is

S9 is shown in the .00 position with megahertz select

grounded in the 40 position, and megahertz ambigui-

lines A and E grounded by S9 rear. Drive motor B1

ty line B is grounded in the 60 position, distinguish-

has positioned S1 so that megahertz select A and E

i n g the two frequency ranges. Switch S8 also

lines are disconnected from the driver motor. When

generates an odd-even megahertz code for the low

S9 is set to the .05 position, S9 rear grounds the

frequency oscillator in the AN/ARC-54 RF sub-

megahertz select B line only. A ground path from

chassis. Switch S8E grounds the even megahertz

the megahertz select B line, through contact 3 on S1

cycle ground line on all even megahertz switch set-

front, energizes the motor. The motor turns S1 in

tings (that is, O, 2,4,6, . . . and so forth) and grounds

the direction shown by the arrows. When the switch

segment leaves contact 3 on S1 front, the ground cir-

the odd megahertz ground line on all odd megahertz

cuit to the motor is opened and the motor stops. The

settings. The combination of switches S7 and S8

tune the RF subchassis to any whole megahertz fre-

same action occurs for other positions of the switch.

quency in the 30- to 70-megahertz frequency range.

Table 2-9 below shows the coding for the 0.05 mega-

Table 2-10 below shows the ground for each whole

hertz selector switch.

c. Whole Megahertz Tuning. Figure 2-31 shows

megahertz setting.

the complete test set tuning circuit. Switches S7 and

2-36. Power Supply Circuits

S8 perform the whole-megahertz tuning. Switch S8

(fig. FO-2)

generates three sets of codes. One code covers the

The test set contains a positive 27.5-volt regulated

30- to 39- and the 50- to 59-megahertz ranges;

power supply, a negative 27.5-volt regulated power

another code covers the 40- to 49- and 60- to 69-

supply, and a positive 500-volt regulated power sup-

megahertz ranges; a third code discriminates be-

ply. Figure FO-2 is a simplified schematic diagram

tween odd and even megahertz by placing alternate

showing the power supplies and associated switch-

grounds on the odd-even megahertz lines. Switch

ing and metering circuits. Paragraphs 2-37 through

S8B and S8D form another five-wire code generator

2-43 describe the power supplies and associated

for the 40- and 60-megahertz ranges. In positions 30

and 50, switch S7 connects the five lines A through

circuits.

E. The codes for frequencies in the 30- and 50-mega-

2-37. Primary Power Circuit

(fig. FO-2)

The primary power circuit for the test set may be

connected for either 115-volt operation or 230-volt

operation by changing the connection of plug P1.

Figure FO-2 shows P1 connected to J30. Wires on

jack J30 connect the primary windings of trans-

former T1 in parallel. Under this condition, the unit

operates from a 115-volt power source. For 230-volt

operation, plug P1 connects to J31. In this case, the

primary windings are connected in series. Interlock

switch S12 disconnects power from transformer T1

when the unit is taken out of the case. Taps on the

primary of transformer T1 are connected to ter-

minal board TB1. The connection shown in figure

FO-2 are for normal line voltages of 115/230 volts. If

low line voltage conditions exist, wires from pins A

and B of plug PI are connected to terminals 3 and 4,

respectively, on terminal board TB1. Using these

connections, the equipment operates from a 105-volt

Figure 2-30. Four-wire reentrant tuning system, simplified

schematic diagram.

or a 210-volt power source, depending on the place-

2-73