TM 11-5840-360-14-1-1
4.9.4 Receiver Circuits (V4)
The high voltage power supply provides the
following operating voltages for the modulator:
The receiver circuits are identical to the receiver
+11.5 KVdc (anode)
circuits in the X-band receiver transmitter and are
+1250 Vdc (screen grid)
described in paragraph 4.2.4.
-550 Vdc (control grid)
4.9.5 Video Amplifier Circuits (V4)
4.10 ANTENNA AS-3195 AND ANTENNA PEDESTAL
AB-1248 (V4)
The video amplifier circuits are identical to the
circuits in Video Amplifier AM-6932 and are described in
The antenna is an S-band end-fed slotted
waveguide array mounted on the antenna pedestal. The
antenna pedestal contains the antenna drive motor,
4.9.6 Resolver Drive Circuits (V4)
drive system, sine-cosine resolver, syncho transmitter
and heading line switch.
RF energy from the transmitter is coupled and
The resolver drive circuits are identical to the
directed to the slotted waveguide array. Energy is
circuits in Video Amplifier AM-6932 and are described in
radiated from the array in a narrow un-directional beam,
so that the bearing of an object reflecting energy can be
determined to within approximately 1 Vertically, the
.
4.9.7 Built-in Test Circuits (V4)
beam is relatively wide so that the roll and pitch of the
vessel will not normally impair the antenna direct line of
The built-in test circuits provide a means of
sight to the horizon. The antenna radiates the pulse of
monitoring and controlling the receiver transmitter
high frequency energy, and receives the reflected pulse
during maintenance. Meter Ml, in conjunction with the
of energy when the transmitter is off.
MONITOR SELECT switch, provides an indication of
The slotted waveguide array in continuously
crystal currents, high voltage, magnetron current, and is
rotated by the drive system which reduces the antenna
also used for tuning. The LOCAL TEST switch permits
motor shaft speed to the desired antenna rotation speed.
local control of the receiver transmitter (off, standby,
The resolver is an electro-mechanical device which
on). The LOCAL PRF SELECTOR selects either
converts the rotation and instantaneous direction of the
remote (indicator controlled) or local (short, medium,
antenna into electrical signals that cause the PPI trace
long) pulse repetition rates for test purposes.
to rotate in synchronism with the antenna. The heading
line is generated by means of a reed switch that
4.9.8 Power Control and Power Supplies (V4)
momentarily closes once every revolution. Figure 4-11
is a functional block diagram of the antenna and
Primary input power to the receiver transmitter
pedestal.
(115 Vac, single phase, 60 Hz and 440 Vac, three
phase, 60 Hz) is controlled by the transmit enable lines
4.10.1 Antenna Drive Mechanism (V4)
which are closed when the indicator POWER switch is
set to the ST BY or TX ON position. The receiver
transmitter LOCAL TEST switch is connected in parallel
The antenna drive mechanism consists of a
with the indicator POWER switch to provide
1horsepower drive motor and a gear reducer assembly.
independent turn-on capability to standby at the receiver
Operating power for the motor is supplied from the
transmitter for maintenance.
receiver transmitter through safety switch SI, the
The 440 Vac, switched by a power contactor to
interlock switch and the normally closed thermostat
provide antenna drive motor power, is also switch
switch. The motor drives the gear reducer assembly by
controlled by the receiver transmitter ANT ROTATION
means of a belt to provide antenna rotation at a speed
switch. The low voltage power supply provides the
of approximately 33 rpm.
following operating voltages for the receiver transmitter
circuits:
4.10.2 Radiating Characteristics (V4)
+5 and +12 Vdc (logic circuits)
The antenna array is horizontally polarized to
+26 Vdc (modulator filament)
produce a horizontal beam width of approximately 2
+120 Vdc (pulse drive)
degrees and a vertical beam width of approximately 23
-12 Vdc
degrees. The array also produces horizontal sidelobes
-550 Vdc
within 10 degrees (up to 29 dB down) of the main lobe,
or more than 10 degrees (greater than 30 dB down).
When the system is in operation, the peak power
transmitted by the antenna is approximately 50 kW.
4-19
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