TM 1-1520-238-10
Change 8
4-69
Section III.
ACTIVE AND PASSIVE DEFENSE EQUIPMENT
4.34A INFRARED COUNTERMEASURES SET
AN/ALQ-144A, -144(V)3.
WARNING
Do not continuously look at the infrared
countermeasure transmitter (fig 2-2) dur-
ing operation, or for a period of over 1
minute from a distance of less than 3 feet.
Skin exposure to countermeasure radi-
ation for longer than 10 seconds at a
distance less than 4 inches shall be
avoided.
CAUTION
The infrared countermeasures set (IR
jammer) should be operated for a mini-
mum of 15 minutes after energizing the
system, otherwise life of the source may
be drastically shortened.
The infrared countermeasures set (IR jammer) provides
infrared countermeasure capability. It transmits radiation
modulated mechanically at high and low frequencies us-
ing an electrically heated source. The IR jammer consists
of a control panel (fig 4-20), on the right side of the pilot
instrument panel, and a transmitter, located on the fairing
immediately aft of the main rotor (fig 2-2). A built-in test
monitors operation and alerts the pilot when a malfunction
occurs. If the IR jammer malfunctions, the IR JAM seg-
ment on the pilot caution/warning panel illuminates. The
IR jammer is not monitored by FD/LS. The IR transmitter
receives 28 vdc from the No. 1 essential dc bus through
the IR JAMMER circuit breaker in the electical power cen-
ter when the IR JAM/PWR circuit breaker is closed. The
IR jammer cooling fan receives 28 vdc from the No. 2 es-
sential dc bus through the IR JAM/XMTR circuit breaker.
The IR JAM/PWR and IR JAM/XMTR circuit breakers are
located on the pilot overhead circuit breaker panel.
4.34A.1 Infrared Countermeasures Set Control Panel.
Control of the IR jammer is provided by the IRCM (infrared
countermeasures) part of the IRCM/RDRCM control pan-
el (fig 4-20) located on the right side of the pilot instrument
panel. The control panel receives 28 vdc from the No. 2
essential dc bus through the PEN AIDS CONTR circuit
breaker on the pilot overhead circuit breaker panel. When
the ON-OFF switch on the IRCM panel is set to ON, the
power distribution and control circuits are activated. The
source begins to heat, and the servo motor and drive cir-
cuits are energized, turning on the high and low speed
modulators. A signal is applied to stabilize subsystem op-
erations before energizing the built-in test function. After a
one minute warmup period, the stabilizing signal is re-
moved and the subsystem operates normally. Setting the
ON-OFF switch to OFF causes the power distribution and
control circuits to de-energize the source and initiates a
cool-down period. During the one minute cool-down peri-
od, the servo motor drive circuits remain in operation, ap-
plying power to the motors that cause the modulators to
continue turning and the IR JAM segment on the pilot cau-
tion/warning panel to illuminate. After the cool-down peri-
od, the power distribution and control circuits de-energize,
all subsystem voltages are removed and the IR JAM cau-
tion light segment is extinguished.
4.34B RADAR COUNTERMEASURES SET
AN/ALQ-136.
WARNING
Do not stand within 3 feet of the front of
the transmit antenna when the equipment
is turned on. High frequency electromag-
netic radiation can cause internel burns
without causing any sensation of heat. If
you feel the slightest warming effect
while near the transmit antenna, move
away quickly.
The radar countermeasures set (radar jammer) provides
the helicopter with protection against ground based fire
control radars. When operating, the radar jammer trans-
mits modulating signals at radar frequencies, causing
range and angle measurement errors to the radar. The ra-
dar jammer consists of a control panel (fig 4-20), located
on the right side of the pilot instrument panel, a receiver
transmitter, and transmit and receive antennas. A built-in
test monitors operation and alerts the pilot when a mal-
function occurs. If the radar jammer malfunctions, the
RDR JAM segment on the pilot caution/warning panel illu-
minates. The radar jammer is not monitored by FD/LS.
The receiver/transmitter receives 28 vdc from the No. 2
essential dc bus through the RDR JAMMER circuit break-
er in the electrical power center when the RDR JAM cir-
cuit breaker is closed. The radar jammer set cooling fan
receives 115 vac from the No. 1 essential ac bus through
the RDR JAM AC circuit breaker. The RDR JAM AC and
RDR JAM DC circuit breakers are located on the pilot
overhead circuit breaker panel.
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