labeled ALT COMP. This switch is used to connect
the altitude compensator to the system.
The bottom portion of the control box contains
four knobs. The two on the left side are labeled
BANDPASS. These knobs select the high and low
The knob labeled REC ZERO is a
Turning this knob controls the
pen deflection on the recorder. Depressing the knob
inhibits system output.
The bottom right knob is
labeled gFS, and is used to select one of nine
sensitivity ranges (from
full scale) or
self-test. In the TST position, the self-test function
will be initiated.
AN/ASA-64 SAD Group
The SAD group consists of only one unit-the
ID-1559 magnetic variation indicator (MAG VAR
indicator). This indicator receives the MAD signals
from the ECA, along with roll attitude signals. These
signals are processed and a SAD mark is generated,
which is correlated with the roll input. In cases of
excessive aircraft roll rate, the indicator will generate
a SAD inhibit signal. This signal illuminates the SAD
INHIBIT lights on the selector control panel and the
pilot and copilots navigation advisory panel, letting
the operators know the SAD mark is unreliable.
AN/ASA-65 Magnetic Compensator Group
The magnetic compensator group consists of the
AM-6459 electronic control amplifier (compensator
ECA), C-8935 control-indicator, DT-355 mag-
netometer assembly, three compensating coils,
CP-1390 magnetic field computer, and ID-2254
magnetic field indicator.
AM-6459 ELECTRONIC CONTROL
AMPLIFIER. The electronic control amplifier
(ECA) processes standard magnetic anomaly detector
signals from the MAD subsystems, operator
compensation adjustments, and maneuver signals
from the magnetometer. The ECA provides
compensation currents, which are sent to the MAD
boom compensation coils.
C-8935 COMPENSATOR CONTROL-
INDICATOR. This control-indicator (fig. 4-28)
contains potentiometers for adjustment of the
maneuver and correlated signals into compensating
terms. The potentiometer outputs are routed back to
the ECA to be amplified. From there they are sent to
the compensator coil as compensation signals.
On the face of the control-indicator there are nine
index counters. The top three provide the adjustment
index for the potentiometers in the transverse,
longitudinal, and vertical magnetometer circuits.
They are labeled T (transverse), L (longitudinal), and
V (vertical). The other six (labeled 1 to 6) provide
compensation adjustment for the T, L, and V
The MAG TERM knob selects the magnetic term
to be compensated. This knob must be in the OFF
position unless compensation is required. The RATE
knob selects the speed of the servomotor with 1 being
the slowest and 4 the fastest.
Across the bottom of the faceplate there are four
toggle switches. The POWER-OFF switch provides
power to the unit. The SERVO-OFF switch provides
both ac and dc power to the servomotor system. This
switch must be in the OFF position unless
recompensation is required. The UP-DOWN switch
provides voltage directly to the servomotor selected.
The counter indication will increase or decrease
depending on which way this switch is toggled. The
+/OFF/ switch provides voltage to the servo system.
In the OFF position, the servomotor is operated only
by the UP-DOWN switch.
DT-355 MAGNETOMETER ASSEMBLY.
The magnetometer assembly contains three coils
oriented to sense magnetic strength in each of the
basic longitudinal, transverse, and vertical axes. This
Figure 4-28.-Compensator control-indicator.