DESCRIPTION OF EQUIPMENT.

T.O. 12P4-2APX-142

NAVAIR 16-35C6280-1

TM 11-5641-268-25

markings are illuminated by 21 miniature lamps embedded

required for pilot operation and monitoring of transponder

in the plastic panel. These lamps are not replaceable. Input

systems with AIMS capabilities.

voltage applied to these lamps must not exceed 5 volts DC.

115. DESCRIPTION OF EQUIPMENT.

The panel of the C-6717/APX is red-lighted and that of the

C-7483/APX is white-lighted.

1 16. GENERAL. The transponder set controls, shown in

Figure 11 and listed in paragraph 12, are essentially the

1 21. MASTER SWITCH. The MASTER switch is a five-

same. The major differences are in the method and color of

position rotary switch. In addition to turning the transponder

panel illumination (paragraphs 119 and 120) and the

set on or off, this switch controls the sensitivity of the trans-

number of mounting fasteners (paragraph 117). Except

ponder receiver and provides for emergency reply operation.

for the differences in input voltage required for panel light-

To prevent accidentally switching to the emergency (EMER)

ing, and the C-6280A(P)/APX which uses six turnlock fas-

or the OFF position, the switch knob must be pulled out

teners for installation, the units are interchangeable. Each

before the switch can be turned to either of these positions.

unit measures 5.75 x 5.25 x 3.09 inches and weighs approx-

1 22. OPERATING MODE SELECTION. The transponder

imately 2.75 pounds. Two knob-actuated rotary switches,

set control includes four mode-enabling switches which are

eight toggle switches, and two press-to-test indicator lights

used to select the operating mode of the transponder set.

are mounted on the panel. The functions of these controls

These are three-position toggle switches which, besides the

and indicators are described in Table 11. No electron

ON and OUT (off) positions, also include a momentary

tubes, semiconductor devices, resistors, capacitors, or in-

position for test signal selection.

ductors are used.

123. REPLY CODE SELECTION. The transponder set

117. INSTALLATION. The transponder set control is

control includes separate groups of thumbwheel switches

designed for installation in a standard aircraft control panel

for selecting the codes for Mode 1 and Mode 3/A replies.

and is equipped with turnlock fasteners for easy installa-

Code selection controls for Mode 2 replies are usually lo-

tion and removal. The C-6280(P)/APX, C-6717/APX, and

cated on one of the other units of the transponder set. Two

C-7483/APX are each equipped with four turnlock fasten-

switches are used for Mode 1 and four are used for Mode

ers while the C-6280A(P)/APX is equipped with six turnlock

3/A. All switches include indication knobs which in com-

fasteners. The unit is installed in a position that is accessible

bination digitally display the selected code number.

to the operator. Electrical connections are made through a

55-pin connector on the rear of the unit. The transponder

124. IDENTIFIER PULSE SELECTION. The transpon-

set control is connected to the other units of the transpon-

der set control includes a three-position toggle switch for

der system through this connector and associated aircraft

identifier pulse selection. The identifier pulse is selected

wiring. External wiring for a typical installation of the trans-

when the switch is held in the momentary IDENT position.

ponder set control is shown in Figure 12.

With the switch set to the MIC position, the identifier pulse

is selected when the microphone keying switch (not part of

118. PANEL ILLUMINATION. The markings on the plas-

the transponder set control) is closed.

tic panel of the transponder set control are illuminated

from behind and glow with a red, white, or blue-white light.

125. TEST PROVISIONS. A three-position toggle switch

The light is also used to illuminate the numerals on the

on the transponder set control is used to select transponder

thumbwheel switch knobs and the lettering on the rotary

test operation. When Transponder Test Set TS-1843( )/APX

switch dials.

is included in the installation, the MON position of the

switch turns on the monitoring circuits of the test set. The

119. On the C-6280(P)/APX and the C-6280A(P)/-APX,

RAD TEST position of the switch is used to enable an

the light is provided by five replaceable incandescent lamps.

appropriately equipped transponder set to reply to TEST

The color of the light is determined by the color of the

mode interrogations from an AN/APM-123(V)( ) or similar

falter in the panel light holder. Since the transponder set

equipment.

control is designed for use in various aircraft which may have

126. Each of the four mode-enabling toggle switches on

different panel "lighting requirements, it is supplied with

the transponder set control includes a momentary TEST

panel light holders with blue-white, red, or clear falters and

position. The TEST position, when selected, allows a locally-

either 6- or 28-volt lamps. The units can be converted for a

generated interrogation signal from the transponder monitor

different panel lighting requirement by changing the lamps

and holders. A two-letter category, which is stamped on the

(such as Transponder Test Set TS-1843( )/APX) to be applied

to the transponder set. Transponder set replies to the test

packing carton, has been assigned to indicate how the unit

has been equipped. These categories are: A, 6-volt lamps;

signal are indicated by the TEST indicator light.

B, 28-volt lamps; C, blue-white falters; D, red falters; and E,

127. MODE 4 CONTROLS. The controls and indicator

clear filters.

for Mode 4 operation are grouped together along the left side

of the control panel. A MODE 4 ON-OUT toggle switch is

120. On the C-6717/APX and the C-7483/APX, the panel