Aviation Electronics Technician 1 - Historic Naval Ships Association

7.8.9.10.11.12.13.14.15.16.17.SQ control knob–Controls the amount ofsquelch threshold voltage in VO and AMEoperations.SQ OFF switch–When this switch is pressed,the squelch circuits are disabled.CPLR READY indicator–This indicator willilluminate when the associated coupler isproperly tuned.CPLR FAULT indicator–This indicator willilluminate to indicate improper tuning of theassociated coupler.SYS READY indicator–This indicator willilluminate when the radio set has passed theself-test routine.SYS FAULT indicator–This indicator willilluminate anytime the radio set fails self-test.RESET switch–This switch resets the SYSFAULT indicator to a GO condition after aNO-GO condition was detectedXMTR OFF indicator–When this indicator isilluminated the radio set cannot be used totransmit. This indicator will come on during the3-minute warmup period (the first 3 minutes ofinitial power up), and anytime the operatingfrequency is changed by more than 1 MHz.Other than that, anytime there is a fault in thesystem that affects the transmitter, thisindicator will illuminate.VOL control–This control knob is not used inthe P-3 aircraft configuration.BLANKER ON switch–This switch is not usedin the P-3 aircraft configuration.COND switch–This switch selects the radioset’s condition of operation.a. OFF–This position removes primary powerfrom the radio set.b. STBY–Applies power to the radio set’s RFAmp final stage filament, frequencystandard and other critical circuits.c. HI–Energizes the radio set and sets thetransmitter for high-power output.d. LO–Energizes the radio set and sets thetransmitter for low-power output.e. TEST–Initializes the radio set’s self-testfunctions.18. MODE switch–This switch selects the radioset’s mode of operation.a.b.c.d.VO–This position permits forced modeselection by the COMM system selectorpanel.AME–This position permits AMEtransmission and reception.CW–With the switch in this position, theradio set will transmit and receivecontinuous-wave signals.DATA, DIV, LSB–In this position, permitsforced mode selection by the COMM systemselector panel.CU-2070/ARC CouplerThe CU-2070/ARC coupler (fig. 1-12) providesimpedance matching between the receiver transmitterand the antenna. The lightning arrester provides a sparkgap to protect the radio if lightning strikes the long-wireantenna.Long-wire AntennaThere are two antennas used in the P-3 aircraft forthe HF system. Both are located external of the aircraft,and stretch from the top of the vertical stabilizer to thefuselage. The one on the left is used by HF-1, and theone on the right is for the HF-2 radio set. Both of the topmounts for the antennas are the breakaway type. If eitherantenna breaks in flight, the wire will depart the aircraft.This is designed for safety reasons. Should the wire gethung up and not depart the aircraft, structural damagecould occur from the wire whipping against thefuselage.TSEC/KY-75 Security UnitThe TSEC/KY-75 provides the encoding anddecoding of the signals when the radio set is in the ciphermode.Figure 1-12.-CU-2070/ARC coupler.1-18