GDR 66 Installation Manual
Page 2-3
190-00303-24
Revision A
2.4 Cabling and Wiring
Refer to the interconnect examples in Appendix B for wire gauge guidance.
The power connection can be run with three AWG #18 wires back to the breaker or can be spliced near the
unit to one AWG #16 or larger wire. Special thin-wall heat shrink tubing is also provided to insulate the
extended barrels inside the backshell. If using AWG #18 barrel contacts, ensure that no two contacts are
mounted directly adjacent to each other. This minimizes the risk of contacts touching and shorting to
adjacent pins and to ground.
Ensure that routing of the wiring does not come in contact with sources of heat, RF or EMI interference.
Check that there is ample space for the cabling and mating connectors. Avoid sharp bends in cabling and
routing near aircraft control cables.
Coaxial cable with 50
Ω
nominal impedance and meeting applicable aviation regulations should be used for
the installation.
RTCA DO-224A assumes 3dB of cable loss in its VDL Typical Uplink Power
Budget. Losses greater than 3dB can reduce transceiver range.
Cabling for the GDR 66 should not be routed near components or cabling which are sources of electrical
noise. Route the GPS, VOR/LOC, and Glideslope antenna cables as far as possible away from all COM
transceivers and antenna cables.
2.5 Cooling Air
Dedicated cooling is not required for the GDR 66 to meet indicated EQF categories. Thermal analysis
must be performed to verify that high temperature limits implied by the indicated EQF categories for the
GDR 66 are not exceeded during normal operation of the aircraft. Guidance can be found in the Garmin
Integrated Avionics System Thermal Management Plan document (GPN 190-00313-50) and the Garmin
Integrated Avionics System Thermal Validation Procedure (GPN 190-00313-51).
Contact Garmin for additional cooling guidance.
NOTE
DRAFT
