Garmin GDL 90 Installation Manual

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Installation ProceduresGDL 90 Installation Manual 560-1049-00 Rev B 2-9should be considered when computing the cable loss. A typical loss of -0.2 dB can be used for eachconnection. The typical cable loss for 20 feet of RG-400 coax with a connector one each end is 4 dB.During the post-installation checkout, susceptibility to harmonics of VHF comm. transmitters will beevaluated. If problems arise, then better isolation, or distance, may be required between the GPS andcomm antennas, or a 1575.42 MHz notch filter may be installed in series with the antenna coax of theVHF comm transceiver to reduce or eliminate the harmonic interference. A notch filter (part #162-1059)is available from Garmin AT.If a VHF comm transmitter causes problems with the GPS on the selected frequencies as listed in thepost-installation checkout, the problem may be due to the ELT. This can be verified by disconnecting theELT antenna coax at the ELT unit. If the ELT is found to cause the problem, then contact the ELTmanufacturer or replace the ELT.0.125Insulation1.000STEP 1CableShrinkTubeMatching RingCapSTEP 3STEP 4-Slide shrink tube over cable.-Strip cable as shown.Solder CenterConductor-Solder cap into place, 2 Places.-Shrink tube as shown.Solder Cap2 PlacesSTEP 2.125Shield 0.250-Flare Outer Shield as ShownSolder Outer Shieldto Connector -Place cable in connector as shown placing innershield inside connector.-Flatten outer shield against connector.-Solder outer shield to connector.-Solder center conductor-Slide matching ring into connector and aroundconductor.-Attach cap.Figure 2-7. Right Angle Coax Connector Assembly2.6.2 UAT ANTENNASThe UAT antenna is a standard 50Ω vertically polarized L-band antenna that operates at 978 MHz. Anyantenna meeting the requirements of TSO-C66, C74, C112 or C154 and presenting a VSWR of less than1.7:1 at 978 Mhz is acceptable. Follow the antenna manufacturer’s installation instructions for mountingantennas.