AN/APX-72 Mode 4 Tests.

TM 11-6625-667-12/NAVAIR 16-30APM-123-1/TO 33A1-3-367-1

MODE 4 code A/B switch to A and the PUSH TO TEST

Reply code

Altitude

ABCD

switch to the LOCK position, and (when operating the

10,100. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

test set) observe the following

10,200 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

(a) On the test set, the REJECT light should

light.

(5) Press the test set PUSH to TEST switch. The

(b) Audio tone should be heard in headset.

ACCEPT indicator should light. If the REJECT indica-

(c) IFF CAUTION light located on aircraft in-

tor lights, set the altitude one increment (100 feet)

strument panel should light.

above and below the test setting. An accept condition

(10) Using KIK-18/TSEC key the KIT-lA/TSEC

indicates the transponder set reply is normal; this ac-

and close access door. Observe same indications listed

tion accounts for the normal deviations of the altitude

in (9) above. Release PUSH TO TEST switch.

digitizer.

(11) On C-6280A(P)/APX, place the MODE 4

f. AN/APX-72 Mode 4 Tests.

switch to ON.

CAUTION

(12) On the test set, briefly depress the PUSH TO

When using the AN/APM-123(V) for testing

TEST switch and observe the following

MODE 4, be sure that the REJECT light

(a) On the test set, first the REJECT light comes

comes on momentarily before the ACCEPT

on and then the ACCEPT light.

light after depressing the PUSH TO TEST

(b) On the C-6280A(P)/APX, the REPLY light

button. If only the ACCEPT light comes on,

should light.

the transponder test set is defective. Refer it

(c) Audio tone should be heard in headset.

to a higher maintenance category for repair.

(d) Aircraft IFF CAUTION light should be off.

IT IS POSSIBLE THAT THE AN/APX-72

(13) On the C-6280A(P)/APX, place the

MAY BE DEFECTIVE IN MODE 4 IF THE

AUDIO/LIGHT switch to the LIGHT position, and

REJECT LIGHT DOES NOT COME ON

repeat the above test. Audio tone should not be heard,

BEFORE THE ACCEPT LIGHT ON THE

but REPLY light should light.

AN/APM-123(V)(*).

(14) On the test set, place the MODE 4 CODE A/B

(1) Prepare equipment for operation in accordance

switch to B and briefly depress the PUSH TO TEST

with instructions in paragraph 2-7.

button. The REJECT light should come on and stay on.

(2) Apply power to the AN/APX-72.

Return MODE 4 CODE A/B switch to A.

(3) Connect Interrogator Computer KIR-lA/TSEC

(15) On the test set, place the MODE 4 VER BIT 1

t o test set MODE 4 connector using cable

switch to 1 and briefly depress the PUSH TO TEST

CX-12216/APM-123(V). On the test set, place the

switch. The REJECT light shall light and remain

MODE switch to MODE 4. ZEROIZE light on the test

lighted.

set should light.

(16) On the C-6280A(P)/APX hold the RAD

(4) Using Code Changer Key KIK-18/TSEC, key

TEST-MON switch in the RAD TEST position and

the KIR-lA/TSEC and close the access door. ZEROIZE

repeat test in (15) above. The REJECT light should

light on the test set should go out.

come on momentarily and then the ACCEPT light.

(5) Install Computer KIT-LA/TSEC in the

Return MODE 4 VER BIT 1 switch to OFF.

aircraft.

(17) On the test set, place the MODE 4 VER BIT 2

(6) Turn the MASTER switch on Transponder Set

switch to 2 and briefly depress the PUSH TO TEST

Control C-6280A(P)/APX to STBY.

switch. The REJECT light should light. Return MODE

NOTE

4 VER BIT 2 switch to OFF.

Equipment must be in STANDBY for at least

(18) On the test set, place the ISLS switch to ON

2 minutes after power is applied.

and briefly depress the PUSH TO TEST switch. The

(7) Connect headset to aircraft intercom system.

REJECT light should light. Return ISLS switch to

(8) Set the controls on the C-6280A (P)/APX as

OFF.

follows:

(19) On aircraft with rigid landing gear, set IFF

Control

Position

CODE HOLD switch located on aircraft instrument

MASTER. . . . . . . . . . . . . . . . . . . . . . . . . . . . NORM

TEST M-1/OUT . . . . . . . . . . . . . . . . . . . . . . . . . OUT

panel to ON. IFF CODE HOLD light located on aircraft

TEST M-2/OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OUT

instrument panel should light. On aircraft with com-

TEST M-3/OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OUT

pression or retractable landing gear, make certain

TEST MC/OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OUT

landing gear is in a stable condition so that the auto-

AUDIO/OUT/LIGHT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AUDIO

matic IFF CODE HOLD switch on landing gear is acti-

CODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A

MODE 4 ON/OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. OUT

vated and remains so.

(9) On the test set, place the FUNCTION switch to

(20) On C-6280A(P)/APX, place CODE switch to

SYSTEM, the MODE 4 DIR/RAD switch to DIR, the

HOLD, then return to A.

Change 3 2-13