2. Mode M-1, M-2, M-3/A, M-C, or MODE 4
switches Select desired mode.
3. IP Switch IDENT, when required, to transmit
identification of position pulses or set IP switch
to MIC to transmit IP pulse only when micro-
phone press-to-talk switch is actuated. (IP
pulses will be for 15 to 30-second duration when
b. Emergency Mode.
During an emergency or dis-
tress condition, the APX-100(V) may be used to transmit
specially coded emergency signals on MODE 1, 2, 3/A,
and 4 to all interrogating stations. Those emergency sig-
nals will be transmitted as long as the MASTER control
switch on the control panel remains in EMER.
1. MASTER control switch EMER.
c. Stopping Procedure.
Refer to paragraph 3.17.4
a. before stopping transponder.
1. MASTER control switch OFF.
3.17.5 Transponder Computer KIT-1A/TSEC and
The transponder computer operates in
conjunction with MODE 4. A caution light on the pilot and
CPG caution/warning panel, marked IFF, will go on when
a malfunction occurs that will prevent a reply when interro-
gated or the KIT-1A or KIT-1C computers have failed.
MODE 4 operation is selected by placing the MODE 4
switch ON. Placing the MODE 4 switch to OUT disables
MODE 4. As with the other modes of the transponder, the
MASTER control switch must be placed in the NORM
position to provide power and permit functioning of the se-
lected modes. MODE 4 CODE switch is placarded ZERO,
B, A, and HOLD. The switch must be lifted over a detent
when rotated to ZERO. Position A selects the MODE 4
CODE for one period, and position B selects the MODE 4
CODE for another period. The switch is spring-loaded to
return from HOLD to the A position. Both A and B codes
are either mechanically inserted into the KIT-1A or elec-
tronically inserted into the KIT-1C. A KYK-13 or similar
keying device is used to load the KIT-1C. The KIT-1C
must have operable batteries or have been turned on, as
previously described, before it will accept and hold the
codes. The KIT-1A does not require power because it is
mechanically keyed. Once keyed the KIT-1A and KIT-1C
(with operable batteries) will retain the codes regardless
of MASTER control switch position or helicopter power as
long as the helicopter is on the ground. Once the helicop-
ter has become airborne (determined by the squat switch)
the MODE 4 codes will automatically zeroize anytime the
MASTER control switch or helicopter power is turned off
or interrupted. The codes may be retained by using the
HOLD function. After landing place the MODE 4 CODE
selector switch to HOLD and release before turning the
MASTER control switch OFF or helicopter power off. Al-
low approximately 15 seconds for the HOLD function to
operate before turning the MASTER control switch OFF
or helicopter power off. The HOLD function must be se-
lected with the helicopter on the ground (determined by
the squat switch). Selecting the HOLD function while the
helicopter is airborne has no effect whatsoever. MODE 4
codes can be zeroized anytime the MASTER control
switch is not in the OFF position and the helicopter is pow-
ered by placing the MODE 4 CODE switch in the ZERO
position. Zeroizing is immediate. The transponder com-
puter KIT-1A/TSEC and KIT-1C/TSEC operation is classi-