CHAPTER 2. OPERATION

TM 11-5820-518-20

CHAPTER 2

OPERATION

Section I. OPERATING INSTRUCTIONS

RT-702/ARC-51X, and the C-6287/ARC-51BX must

2-1.

Operator's Controls and Indicators

be used with the RT-742(*)/ARC-51BX. The chart be-

(figs. 2-1 and 2-2)

low lists the operator's controls and indicators and

Note. The C-4677/ARC-61X must be used with the

their functions.

Control or indicator

Function

Function select switch (4-position rotary

Applies power to radio set and selects type of operation,

switch).

Action

switch pos

Removes operating power from radio set.

OFF

T/R

Applies power to radio set and permits trans-

mission and reception; guard receiver is not

operative.

T/R+G

Permits transmission and reception; guard re-

ceiver is operative.

ADF

Permits transmission, reception, and automatic

direction finder operation; guard receiver is

not operative.

VOL control ------------------------------

Controls level of audio applied to headset.

SENS control (C-4677/ARC-51X only) --

Adjusts main receiver sensitivity. When rotated fully clockwise,

SENS control disables squelch.

SQ DISABLE switch

When set to ON, squelch is disabled. When set to OFF, squelch is

(C-6287/ARC-51BX only).

operative.

Mode selector switch (3-position rotary

Determines manner in which frequencies are selected.

switch, C-6287/ARC51BX only).

Action

switch pos

PRESET CHAN

Permits selection of one of 20 channels by means

of preset channel control.

MAN

Permits frequency selection by means of mega-

cycle controls.

automatically t u n e s t o

Receiver-transmitter

GD XMT

guard channel frequency.

Preset channel control (20-position rotary

Permits selection of any one of 20 preset channels.

switch, C-6287/ARC-51BX only).

Preset channel indicator -----------------------

Indicates preset channel selected by preset channel control.

10-megacycle control (18-position rotary

Selects portion of receiver-transmitter operating frequency in 10-

megacycle steps (first two numbers, left to right, on C4677/ARC

switch ).

51X MEGACYCLES indicator, and C-6287/ARC-51BX MC in-

dicator).

l-megacycle control (10-position rotary

Selects portion of receiver-transmitter operating frequency in 1-

switch ).

megacycle steps (third number on MEGACYCLES indicator).

0.l-megacycle control (10-position rotary

Selects portion of receiver-transmitter operating frequency in 0.1-

switch on C-4677/ARC-51X and 20-

megacycle steps (fourth number on C-4677/ARC51X MEGA-

position rotary switch on

CYCLES indicator), or 0.05-megacycle steps (fourth and fifth

C-6287/ARC-51BX).

numbers on C-6287/ARC-51BX MC indicator).

2-1