OPERATING CONTROLS AND INDICATORS.

T.O. 12P4-2APX-142

NAVAIR 16-35C6280-l

TM 11-5841-268-25

129. OPERATING CONTROLS AND INDICATORS.

used to enable the transponder set to process Mode 4 inter-

rogations. The handle of this switch is designed to permit

130. The operating controls and indicators and their panel

recognition by touch. Also, to prevent accidental setting of

markings, shown in Figure 13, are the same on all the

the switch to OUT, the handle must be pulled outward be-

transponder set controls. The functions of these controls

fore it can be lowered to the OUT position. A three-position

and indicators are described in Table 11.

toggle switch selects Mode 4 monitoring and the monitoring

method. The AUDIO position selects both audio and reply-

light monitoring; the LIGHT position selects reply-light mon-

itoring only; and the OUT position turns off the monitor-

ing circuits. A knob-actuated rotary switch is used for Mode

4 CODE selection. To prevent the control from being acci-

dentally set to the ZERO position, the knob must be pulled

out before the switch can be turned to ZERO. The switch

also includes a spring-return which automatically returns the

switch and knob to the A position from the HOLD position.

128. INDICATOR LIGHTS. Both the TEST and REPLY

indicator lights are press-to-test types. Operation of the lamps

can be checked by pressing the cap in and observing that the

lamp lights, Also, the light may be dimmed by turning the

cap clockwise. The TEST light is associated with the trans-

ponder set test circuits, while the REPLY light is part of the

Mode 4 control circuits.

Figure 13. Operating Controls and lndicators

TABLE 1-1. OPERATING CONTROLS AND INDICATORS

FUNCTION

CONTROL OR INDICATOR

Turns transponder set on and off, selects receiver sensitivity, and selects emer-

MASTER Switch

gency operation:

Removes power from transponder set and transponder computer.

OFF

Enables transponder receiver and computer; disables transponder

STBY

transmitter.

Places transponder set in operation at reduced receiver sensitivity.

LOW

NORM

Places transponder set in operation at normal receiver sensitivity.

EMER

Causes automatic transmission of emergency reply signals to Mode

1, 2, or 3/A interrogations only, regardless of mode switch settings

(not affected by Mode C or 4 interrogations).

ON position selects Mode 1 operation of transponder set; TEST position selects

M-1 Switch

Mode 1 test operation; OUT position turns off Mode 1 operation.

M-2 Switch

ON position selects Mode 2 operation of transponder set; TEST position selects

Mode 2 test operation; OUT position turns off Mode 2 operation.

M-3/A Switch

ON position selects Mode 3/A operation of transponder set; TEST position selects

Mode 3/a test operation; OUT position turns off Mode 3/A operation.

ON position selects Mode C operation of transponder set; TEST position selects

M-C Switch

Mode C test operation; OUT position turns off Mode C operation.

Select and indicate Mode 1 two-digit reply code number.

MODE 1 Reply-code

Selector Switches (2)

Select and indicate Mode 3/A four-digit reply code number.

MODE 3/A Reply-code

Selector Switches (4)

IDENT position selects identifier pulse; MIC position permits selection of identi-

IDENT-OUT-MIC Switch

fier pulse when microphone keying switch is closed; OUT position turns off iden-

tifier pulse circuit.

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