TM106601_(7/01) 2-4
USE OR DISCLOSURE OF DATA CONTAINED ON THIS PAGE IS SUBJECT TO THE
RESTRICTION ON THE TITLE PAGE OF THIS DOCUMENT.
COMMAND SYSTEMS DIVISION
2.6 POST-INSTALLATION CHECK
Note
+ When an 18-inch array is installed on the
antenna drive unit, a spacer is required between
the bulkhead and the drive unit to prevent the
array from hitting the bulkhead during the 120°
scans. Refer to Table 1.2-1.
(a) Shock Mounting and Ventilation
Shock mounting is not required. The antenna is designed to operate in the unpressurized nose section
of aircraft and ventilation is not required.
(b) Pressurization
The antenna with a high altitude array is designed to operate within ambient air pressures ranging
from sea level (and below) to an altitude of 55,000 feet, without pressurization. The antenna is
installed in the nose section of the aircraft, which is not normally pressurized. Thus, if the RT
unit is installed in the pressurized cabin section, the electrical and RF transmission lines feeding
the antenna must be brought into the nose section through the use of an airtight seal at the
bulkhead feed through. A pressure window should also be placed in the installation waveguide.
(c) Orientation
The mounting position of the antenna must satisfy the following conditions:
(1) Centerline of antenna must be located at aircraft centerline or within three inches below
horizontal centerline on vertical centerline.
(2) Azimuth scan axis of antenna must parallel spin axis of the stabilizing vertical gyro.
(3) Tilt axis of antenna must parallel pitch axis of aircraft. This should result in the azimuth
spin axis of the antenna lying mutually perpendicular to the roll and pitch axes of the
aircraft.
(4) To insure that targets are displayed in their proper relative positions with respect to the
aircraft, the radar beam must radiate forward, perpendicular to the pitch axis of the aircraft,
and in the plane of flight path when the antenna is positioned at zero degrees in both azimuth
and tilt. The antenna stabilization system will function properly only when the azimuth spin
axis of the antenna parallels the spin axis of the stabilizing vertical gyro. Should an
ambiguity exist between the two spin axes, an inherent error is developed in the system. The
error is evidenced by uneven azimuth illumination of terrain as the antenna scans. This
condition is undesirable and may cause some confusion when interpreting the radar display.
Therefore, it is important that the antenna and gyro spin axes be in coincidence (both pitch
and roll planes) when the antenna is being mounted. THE SAME REFERENCE
CRITERION FOR MOUNTING THE GYRO SHOULD BE EMPLOYED FOR
LEVELING AND MOUNTING THE ANTENNA.
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