Garmin GTR 225 Installation Manual

Also see for GNC 255: Pilot's guide

Contents

Garmin GTR 225 Installation Manual Manual pdf 29 page image

190-01182-02 GTR 225/GNC 255 TSO Installation ManualRev. B Page 3-13 INSTALLATION OVERVIEW3.1 IntroductionAlways follow acceptable avionics installation practices per AC 43.13-1B, AC 43.13-2B, or later FAAapproved revisions of these documents. The communications installation instructions have been preparedto meet the guidance material defined by AC 20-67B, “Airborne VHF Communications EquipmentInstallations.”3.2 Antenna ConsiderationsThis section contains mounting location considerations for the antennas required for the GTR/GNC. Formounting the COM and NAV antennas, refer to the aircraft manufacturer’s data.3.2.1 COM Antenna LocationThe GTR/GNC COM antenna should be well removed from all projections, engines and propellers. Theground plane surface directly below the antenna should be a flat plane over as large an area as possible (18inch square, minimum). The antenna should be mounted a minimum of six feet from any DME or otherCOM antennas, and four feet from any ADF sense antennas. The COM antenna should also be mounted asfar apart as practical from the ELT antenna. Some ELTs have exhibited re-radiation problems that causeinterference with other radios, including GPS. This can happen when the COM (GTR/GNC or any otherCOM) is transmitting on certain frequencies such as 121.15 or 121.175 MHz, which may cause the ELToutput circuit to oscillate from the signal coming in on the ELT antenna coax.If simultaneous use of two COM transceivers is desired (split-COM or simul-comm), the COM antennasshould be spaced for maximum isolation. A configuration of one topside antenna and one bottom sideantenna is recommended. The GTR/GNC does not require a transmit interlock, but other COM radios suchas the GNS 530W may require it for split COM operations.NOTECanadian installations are required to meet Industry Canada specifications for maximumradiation as documented in Radio Specifications Standard 102 (RSS-102). For moreinformation about RF exposure and related Canadian regulatory compliance, contact:Manager, Radio Equipment StandardsIndustry Canada365 Laurier AvenueOttawa, OntarioK1A 0C8In accordance with Canadian Radio Specifications Standard 102 (RSS 102), RF field strengthexposure to persons from an antenna connected to this device should be limited to 60V/m forcontrolled environment and 28 V/m for uncontrolled environment.