Buc-Hpa - Thermal Conduction Path; Buc-Hpa/Waveguide Installation - Honeywell JetWave MCS-8562 Installation And Maintenance Manual

SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
The TX path interconnect loss between the BUC-HPA and the FMA must not exceed 1.5 dB in the
frequency range of 29 to 31 GHz. The loss is from BUC-HPA flange to antenna flange.
The RX path interconnect between the BUC-HPA and the FMA must not exceed 2.0 dB in the
frequency range of 950 to 1950 MHz.
D.

BUC-HPA - Thermal Conduction Path

The transmit operation of the AES is muted if the conduction-cooled BUC-HPA exceeds the
temperature indicated in Table 1-5.
The conduction-cooled BUC-HPA relies on heat conduction through its base to a thermally
conductive path in order to minimize the BUC-HPA temperature. Conduction to the aircraft mounting
plate is dependent on proper installation of the BUC-HPA thermal pad. The outline and installation
drawings in Figure 3-10 provide thermal pad installation instructions.
If the shutdown temperature is exceeded, a low-power mode (non-RF communicating) is entered
until the temperature reduces to approximately 10° below the shutdown temperature. The
temperature measurement on BUC-HPA is done internal to the unit with 5° offset to the baseplate
that is calibrated to compensate for the temperature difference. However with different heating
pattern the real temperature can deviate from the reading.
NOTE:
The BUC-HPA must be electrically bonded to the airframe through contact with the base of the
unit as follows:
- At least one of the four mechanical attachment points must be used for electrical bonding.
- Make sure that the mating surfaces are free from contaminants such as paints or other
non-conductive elements.
- A circular or elongated conductive areas are provided around two or more of the mounting
holes of the equipment base plate.
- The BUC-HPA includes bonding measuring points on the chassis bosses which are not used
for mounting feet.
The BUC-HPA bonding resistance measured from the measuring point and the surface upon which
the unit is mounted, must be less than 2.5 mΩ.
The BUC-HPA bonding and BUC-HPA interconnection details from and to the FMA are detailed
along with the FMA installation instructions in subsequent sections.
E.

BUC-HPA/Waveguide Installation

(1) BUC-HPA Installation Location with the FMA (if applicable)
(a)
EFFECTIVITY
ALL
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JetWave™ MCS-8562 Terminal
When the aircraft is on the ground and the AES is transmitting, and the ambient outside
temperature is very hot, then the mounting plate temperature can be exceeded. The
exact outside air temperature and operating conditions are installation dependent.
Consult with your hardware supplier for further details.
The BUC-HPA install location is airframe specific.
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11 Nov 2020