Aviation Electronics Technician 1 - Historic Naval Ships Association

labeled ALT COMP. This switch is used to connectthe altitude compensator to the system.The bottom portion of the control box containsfour knobs. The two on the left side are labeledBANDPASS. These knobs select the high and lowfrequencies. The knob labeled REC ZERO is adual-purpose knob. Turning this knob controls thepen deflection on the recorder. Depressing the knobinhibits system output. The bottom right knob islabeled gFS, and is used to select one of ninesensitivity ranges (from 0.1γ to 40γ full scale) orself-test. In the TST position, the self-test functionwill be initiated.AN/ASA-64 SAD GroupThe SAD group consists of only one unit-theID-1559 magnetic variation indicator (MAG VARindicator). This indicator receives the MAD signalsfrom the ECA, along with roll attitude signals. Thesesignals are processed and a SAD mark is generated,which is correlated with the roll input. In cases ofexcessive aircraft roll rate, the indicator will generatea SAD inhibit signal. This signal illuminates the SADINHIBIT lights on the selector control panel and thepilot and copilot’s navigation advisory panel, lettingthe operators know the SAD mark is unreliable.AN/ASA-65 Magnetic Compensator GroupThe magnetic compensator group consists of theAM-6459 electronic control amplifier (compensatorECA), C-8935 control-indicator, DT-355 magnetometerassembly, three compensating coils,CP-1390 magnetic field computer, and ID-2254magnetic field indicator.On the face of the control-indicator there are nineindex counters. The top three provide the adjustmentindex for the potentiometers in the transverse,longitudinal, and vertical magnetometer circuits.They are labeled T (transverse), L (longitudinal), andV (vertical). The other six (labeled 1 to 6) providecompensation adjustment for the T, L, and Vmagnetometer circuits.The MAG TERM knob selects the magnetic termto be compensated. This knob must be in the OFFposition unless compensation is required. The RATEknob selects the speed of the servomotor with 1 beingthe slowest and 4 the fastest.Across the bottom of the faceplate there are fourtoggle switches. The POWER-OFF switch providespower to the unit. The SERVO-OFF switch providesboth ac and dc power to the servomotor system. Thisswitch must be in the OFF position unlessrecompensation is required. The UP-DOWN switchprovides voltage directly to the servomotor selected.The counter indication will increase or decreasedepending on which way this switch is toggled. The+/OFF/– switch provides voltage to the servo system.In the OFF position, the servomotor is operated onlyby the UP-DOWN switch.DT-355 MAGNETOMETER ASSEMBLY.—The magnetometer assembly contains three coilsoriented to sense magnetic strength in each of thebasic longitudinal, transverse, and vertical axes. ThisAM-6459 ELECTRONIC CONTROLAMPLIFIER.— The electronic control amplifier(ECA) processes standard magnetic anomaly detectorsignals from the MAD subsystems, operatorcompensation adjustments, and maneuver signalsfrom the magnetometer. The ECA providescompensation currents, which are sent to the MADboom compensation coils.C-8935 COMPENSATOR CONTROL-INDICATOR.— This control-indicator (fig. 4-28)contains potentiometers for adjustment of themaneuver and correlated signals into compensatingterms. The potentiometer outputs are routed back tothe ECA to be amplified. From there they are sent tothe compensator coil as compensation signals.Figure 4-28.-Compensator control-indicator.4-22