TM11-5840-360-14-1-1
AN/SPA-66 indicators.
WARNING
4.11.2 Heading Flash Circuit (V4).
WITH THE SYSTEM OPERATING
AND THE ANTENNA STOPPED, A
The heading flash signal from the antenna. via
RADIATION HAZARD IS PRESENT
the switching unit, is applied to the input protection
WITH 35 FEET OF THE ANTENNA
circuit which limits positive- and negative going
transients. The Schmitt trigger produces a positive-
4.10.3 Antenna Position Circuits (V4)
going transition which is applied to the brighten sweep
flip/flop shift register. The output of the register is
The antenna position circuits provide data to the
applied through the gain controls and mixed into the
indicators to synchronize the indicator sweep with the
video output lines. When selected at the control
indicators mounted on the ANI SPA-25 and AN/SPA-66
B2, synchro transmitter B3 and reed switch S2.
indicators, the heading flash information can be
The stator winding of resolver B2 receives the
removed from the video output lines.
resolver drive input (a 900-Hz square wave) from the
indicator via the receiver transmitter. A compensation
4.11.3 Acknowledge Pulse/Trigger Circuit (VII)
winding on B2 provides a feedback signal back to the
indicator to regulate a constant drive input to the stator
The acknowledge pulse from the receiver
winding. The rotor of B2 is mechanically coupled to the
transmitter, via the switching unit, is applied to the in-put
antenna drive mechanism. Sire-modulated and cosine-
protection circuit which limits positive- and negative-
modulated square-wave outputs from rotor windings of
going transients. The Schmitt trigger generates a noise-
B2 are sent to the indicator to rotate the PPI sweep in
free negative-going transition to fire the single shot
synchronism with the antenna.
multivibrator. The multivibrator output is inverted and
Synchro transmitter B3 provides antenna
applied through the overload protection drivers to
position data to the AN/SPA-25 and AN/SPA-66
provide independent triggers for the AN/SPA-25 and
indicators. Excitation voltage, 115 Vac, 60 Hz, is
AN/SPA-66 indicators. The multivibrator also provides
applied to the rotor winding of B3. The rotor is driven by
a clock signal for the heading flash circuit.
antenna shaft gearing. The outputs, used to position the
AN/SPA-25 and AN/SPS-66 indicator sweeps, are taken
4.11.4 Azimuth Synchro and North Stabilization Circuits
from stator windings of B3.
(V4)
Reed switch S2 can be mechanically adjusted
for a momentary closure when the antenna is positioned
Antenna position signals from the antenna
forward at zero degrees. Closure of S2 provides a
synchro transmitter are connected directly through the
heading flash (HF) trigger to the indicators.
signal data converter to the AN/SPA---25 and AN/ SPS-
66 indicators when the RB/NS switch is in the RB
4.11 SIGNAL DATA CONVERTER CV-3442 (V4)
position. In the NS position the antenna position signals
are applied through the differential generator to the
The signal data converter provides compatible
indicators. The differential generator shaft position is
operating signals to the AN/SPA-25 and AN/SPA-66
controlled by the stepper mot(or' through a 45: 1 gear
from Radar Set AN/SPS-64(V)4. Figure 4-12 is a
reduction train. Ship's heading data from the gyro
functional block diagram of the signal data converter.
compass causes the stepper motor to drive the
differential generator in response to ship's heading
4.11.1 Video Amplifier and FTC Circuits (V4)
changes. The differential generator combines the
antenna position signals with the ships heading data to
Video data from the receiver transmitter, via the
provide north stabilized synchro data to the AN/SPA-25
switching unit, is buffered, differentiated, split and
and AN/ SPA-66 indicators. When the RB/NS switch is
applied to the AN/SPA-25 and AN/SPA-66 indicators.
in the NS position signals are forwarded to the control
Video differentiation, to provide time constants matched
indicators mounted on the AN/SPA-25 and AN!/ SPA-66
to the transmitter pulse widths, is selected at the control
indicators for visual display of the NS condition,
indicators which are mounted on the AN/SPA-25 and
4-21
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