CE-1008
(2) ANTENNA PEDESTAL (See Figure 5-6) - The antenna pedestal used with the Antenna System consists of a
cylindrical riser base which houses the azimuth servo drive mechanism, azimuth synchro assembly, azimuth, electric
pressure brake, and part of the antenna polarization control unit. The azimuth servo drive mechanism consists of a
servoamplifier, an a-c servo motor, and a gear train connected to a vertical tubular shaft, mounted in a precision bearing
assembly, which has a mounting flange on top for mounting the antenna mast. An angle scale, graduated from 0 to 360
degrees, attached to the vertical tubular shaft, and an index marker attached to the stable part of the riser base provide a
visual indication of the pedestal azimuth rotation, and during installation they allow orientation of the pedestal either to
true north or to a selected reference point. A safety switch on the riser base controls operating power to the servo drive.
The azimuth synchro assembly contains two synchros which provide control and data outputs for the azimuth axis, a
cable-wrap potentiometer, and two electric limit switches. Two mechanical stops in the azimuth drive limit rotation of the
pedestal to 300 degrees. The electrical limit switch, which acts as a buffer for the mechanical stops, makes contact
approximately 30 degrees before the mechanical stops. The electric brake, which is released only when power is applied
to the system, prevents movement of the antenna in azimuth when the system is not operating. A detailed description
and theory of operation of the antenna pedestal are contained in Section V of this manual.
(3) ELEVATION DRIVE ASSEMBLY (See Figure 5-10) - The elevation drive assembly, which consists essentially
of a yoke assembly, a housing, and a drive motor, supports the antenna and tilts it in elevation. The yoke assembly, a
non-rotatable assembly with a stationary drive gear, is bolted to an elevation drive support casting which couples the
azimuth drive to the elevation drive. The elevation housing, a U-shaped casting which is bolted to and supports the
antenna, is supported through roller bearings in the yoke assembly. The drive motor, when powered, drives the elevation
housing around the yoke assembly. An angle scale, graduated from 0 to 360 degrees, affixed to the movable housing,
and an index marker affixed to the stable elevation yoke provide a visual indication of the elevation angle of the antenna,
and during installation they allow orientation of the antenna to zero-degree elevation, Two mechanical limit stop
assemblies prevent movement of the elevation housing below -18 degrees and above +98 degrees. An electrical limit
switch, which acts as a buffer for the mechanical stops, makes contact approximately 3 degrees before the mechanical
stops. Two synchros provide control and data outputs for the elevation axis. An electric pressure brake, which is
released only when power is applied to the system, prevents movement of the antenna in elevation when the system is
not operating.
(4)
TYPE I RADOME-PLATFORM -
a.
The type I radome-platform used with the Antenna System consists of an inflatable radome and a
box-type metal construction which serves as the radome base and houses the radome blowers and pressure switches
and the Antenna System. The type I platform measures 6 by 6 by 2.58 feet. The radome, when inflated, has a
maximum diameter of 16 feet.
Revised January 22, 1968
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