Garmin GDL 82 Installation Manual

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Garmin GDL 82 Installation Manual Manual pdf 17 page image

GDL 82 Mooney M20( ) Series STC Installation Manual 190-01810-10Rev. 1Page 10 of 493.3 Pre-Installation: Existing Transponder System CheckThe existing Mode A/C (ATCRBS) transponder to be interfaced to the GDL 82, must meet the following:• The transponder complies with TSO-C74().• The installation of the transponder was previously FAA-Approved.• The existing transponder’s altitude source (altitude serializer/encoder) must comply with TSO-C10(), TSO-C106() or TSO-C88() and have prior FAA approval.• The transponder must pass the pre-installation check procedures in Table 3-2.The existing transponder system’s peak output power and receiver sensitivity must be verified todetermine compatibility with the GDL 82 before the system is installed in the aircraft. The GDL 82introduces no more than 1.5 dB loss in the transmission line as measured at the antenna output.Measurement is performed with a utilized radiated ramp tester, such as an Aeroflex IFR-6000 or TIC TR-220, operated in accordance with the applicable operator’s manual.Table 3-2: Pre-Installation Check ProceduresStep Description Notes1Determine the RF Peak Output Powerand Receiver Sensitivity IAW Part 43,Appendix F, for existing ATCRBSsystem (i.e., transponder system).Record the observed values of RF PeakOutput Power and Receiver Sensitivity.RF Peak Output Power: ___________Class A: > 21.0 dBw (125 Watts)Class B: > 18.5 dBw (70 Watts)Receiver Sensitivity (MTL): _____________Any Class: MTL = -73 ±4 dBm2Subtract the anticipated maximum loss(1.5dB) from the peak output power andadd 1.5dB to the sensitivity valuesdetermined in step 1.<Output Power>dBw - 1.5dB = _________dBw<Sensitivity>dBm + 1.5dB = ___________dBm3Verify that the peak output power andsensitivity are not reduced below therequired minimums.Class A: > 21.0 dBw (125 Watts)Class B: > 18.5 dBw (70 Watts)Any Class: MTL = -73 ±4 dBmConsider the following modifications to help reduce loss in the transponder system, if the results of theprocedure in Table 3-2 do NOT meet the minimum performance specifications of Part 43, Appendix F.Any of the steps, or their combination, can be used.NOTEPerformance of any or all of the following recommendations does not necessarily ensurecompliance with 14 CFR §43, Appendix F.