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.