Aviation Electronics Technician 1 - Historic Naval Ships Association

and the PWR/FILL switch is not in theOFF/ZEROIZE position.5.6.SIG CLR switch–This switch is pressed toenable the till operation if the TSEC/KYK-13 orTSEC/KOI-18 is attached If a fill device is notattached pressing this switch will cause thesecurity unit to preamble.FILL connector–This connector connects thefilling device to the TSEC/KY-75 security unitelectrically. This enables the operator to loadkeys into the security unit.HF FUNCTIONAL DESCRIPTIONFigure 1-13.-TSEC/KY-75 remote control unit.TSEC/KY-75 Remote Control UnitThe TSEC/KY-75 remote control unit (RCU) isshown in figure 1-13. This unit enables the operator tooperate the security unit without moving from theNAV/COMM station in the aircraft. The following is anexplanation of the various controls and indicators on theRCU.Both radio sets function in the same manner; theonly difference between the two is the peripheralequipment used. Figure 1-14 shows a system blockdiagram.Receive FunctionThe RF signal is received by the antenna, coupledthrough the coupler and the de-energizedtransmit-receive relay in the RF amplifier, and finally tothe receiver transmitter receiver RF input. RF-to-audioconversion is accomplished in the receiver section usinginputs from the frequency synthesizer. The recoveredaudio component is amplified to a power level sufficientto be used as an audio input to the peripheral equipment.1.2.3.4.ALARM indicator–This indicator willilluminate whenever there is an alarm conditionin the security unit.TSEC/KY-75 RCU switch–This switch is notused.PWR/FILL switch–This is a four-positionswitch used to select the key and storagelocations for the various codes used.ab.OFF/ZEROIZE–This position will zeroize allvariables stored in the TSEC/KY-75 securityunit. To select this position, the operator mustpull the knob out 1/4 inch and turn itcounterclockwise. This prevents accidentalzeroizing during flight.1, 2, 3–These positions select a particular keyfor the cipher transmission or reception. Theyalso select the storage area when the key isloaded into the TSEC/KY-75.PWR indicator–This indicator will illuminatewhite when power is applied to the security unitTransmit FunctionDuring the transmit function, voice or data signalsfrom the peripheral equipment are switched through theCOMM switching matrix to the USB and LSB transmitaudio inputs to the receiver transmitter. A keying signalis also applied from the peripheral equipment. Foremergency or maintenance operations, voice and keyingsignals can originate at the mic/headset assemblyconnected directly to the receiver transmitter.Figure 1-14.-HF system block diagram.1-19