Avionics Cooling Requirements For Panel Mounted Equipment; Kt 73 Interconnection And Cable Harness Fabrication - Honeywell BENDIX KING KT 73 Installation Manual

Preliminary - Subject To Change Without Notice
BENDIX/KING
2.3.2

AVIONICS COOLING REQUIREMENTS FOR PANEL MOUNTED EQUIPMENT

The greatest single contributor to increased reliability of all modern day avionics is to limit the max-
imum operating temperature of the individual units whether panel or remote mounted. While mod-
ern day individual circuit designs consume much less electrical energy, the watts per cubic inch
dissipated within avionics units remains much the same because of high density packaging tech-
niques utilized. Consequently, the importance of providing avionics stack cooling is essential to
the life span of the equipment.
While each individual unit may not require forced air cooling, the combined heat load of several
units operating in a typical avionics stack will significantly degrade the reliability of the avionics if
provisions for stack cooling are not incorporated in the initial installation. Recommendations on
stack cooling are contained in Honeywell Installation Bulletin #55. Failure to provide stack cooling
will certainly lead to increased avionics maintenance costs and may void the warranty.
2.3.3

KT 73 INTERCONNECTION AND CABLE HARNESS FABRICATION

2.3.3.1 General
The KT 73 Mode S Transponder receives primary power from the aircraft power source. Power
connections, voltage requirements, and circuit breaker requirements are shown on the intercon-
nect diagrams (Figures 2-5 through 2-10).
The length of the wires to parallel pins should be approximately the same length, so that the best
distribution of current can be effected. Honeywell recommends that all wires, including spares as
shown on the interconnect diagram be included in the fabrication of the wiring harness. However;
if full wiring is not desired, the installer should ensure that the minimum wiring requirements for
the features and functions to be used have been incorporated.
When cables are installed in the aircraft, they must be supported firmly enough to prevent move-
ment and should be carefully protected against chaffing. Additional protection should also be pro-
vided in all locations where the cable may be subjected to abuse.
In wire bundles, the cabling should not be tied tightly together as this tends to increase the possi-
bility of noise pickup and similar interference. When routing cables through the aircraft the cables
should cross high level rf lines at right angles.
Prior to installing any equipment, make a continuity check of all wires and cables associated with
the system. Then apply power and check for proper voltages at system connectors, and then re-
move power before completing the installation.
The following guidelines are recommended:
(1) The installing facility will supply and fabricate all external cables (see figures 2-1
through 2-3, 2-5 through 2-15). The required connectors are supplied as part of the
installation kit (P/N 050-03451-0000).
Rev 0, October/2002
NOTE:
The TSO identifies the minimum performance stan-
dards, tests, and other conditions applicable for issu-
ance of design and production approval of the arti-
cle. The TSO applicant is responsible for document-
ing all limitations and conditions suitable for installa-
tion of the article. An applicant requesting approval
for installation of the article within a specific type or
class of product is responsible for determining envi-
ronmental and functional compatibility.
10563I00.JA
KT 73
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