Boeing B737 Maintenance Manual

23-24-00 PAGE 205 JAN 02/07 (10) Audio Modulation NOTE: The power output is approximately 37 dBm © 5 Watts. Ensure adequate attenuation is inserted in-line between the ELT’s 406.025 MHz output and the input to the spectrum analyzer to protect the analyzer’s input circuitry. (a) Connect the equipment as shown below: (b) Set the Spectrum Analyzer as follows: 1) Center Freq: 406.025 MHz 2) Span: 1 MHz 3) Resolution Bandwidth: 1 MHz 4) Vertical Display: 10dB/Div 5) Sweep: Auto 6) Peak/Avg: Peak 7) Reference Level: 30dBm 8) Time/Div: ...

23-24-00 PAGE 214 JAN 02/07 (s) Once the ELT has been tested, as applicable, and reinstalled in the aircraft as described in this Aircraft Maintenance Manual supplement, apply the battery expiration date label provided with the battery pack to the exterior of the ELT (i.e. on the end cap or other visible location). (t) Enter the pertinent battery replacement information in the aircraft log book and fill out any other documentation required by local authority. (u) If you have any questions regarding the Battery Pack Replacement Procedu ...

23-24-00 PAGE 202 JAN 02/07 (3) Remove Battery pack NOTE: The battery pack contains static sensitive parts, take ESD precautions before handling. Remove the four screws from the battery pack. Before proceding further, read the following advisory to avoid damage to the ELT. For detailed instructions refer to step (19) and Figure 3. WARNING: The battery pack is connected to the ELT via short interconnect harnesses which limit the distance of separation between the two components prior to disconnecting the harnesses. Proceed as follows ...

23-24-00 PAGE 214 JAN 02/07 (a) Lay the ELT on its side. (b) Carefully lift the battery pack away from the ELT and lay along side the ELT. (c) Carefully disconnect the harness from the 8-pin connector on the small circuit board in the battery pack. Do not short connector pins. (d) Disconnect 2-pin harness. (e) Inspect the battery pack and underside of ELT. (f) Battery cells, components and connectors should be corrosion free. The underside of ELT should be corrosion free. (g) Inspect for any broken wires or connections. (h) Ensure the ...

23-24-00 PAGE 002 JAN 02/07 G. One advantage of the 406.025 MHz transmitter is that it will produce a much more accurate position, typically 1 to 2 kilometers as compared to 15 to 20 kilometers for 121.5/243.0 Mhz transmitters. When coupled with the aircraft’s navigation system the position accuracy improves to approximately 100 meters. The ELT also transmits a digital message which allows the search and rescue authorities to contact the owner/operator of the aircraft through a database. Information contained in the database that m ...

23-24-00 PAGE 203 JAN 02/07 NOTE: If the check out is going to conclude with step (5) below, then reseat the battery pack on the ELT, dressing the harness wires away from the standoffs to avoid pinching the wires between the battery pack and the standoffs. Reinstall the four Phillips head screws and tighten securely. Do not over torque the screws. (5) G-switch Check NOTE: The ELT cannot be activated in this way unless pins 5 and 8 are jumpered (this happens automatically when the unit is locked into the mounting tray with the conne ...

23-24-00 PAGE 204 JAN 02/07 (b) Set the Spectrum Analyzer as follows: 1) Center Freq: 121.5 MHz 2) Span: 1 MHz 3) Resolution Bandwidth: 1 MHz 4) Vertical Display: 10dB/Div 5) Sweep: Auto 6) Peak/Avg: Peak 7) Reference Level: 30dBm 8) Time/Div: 20ms (c) Adjust the reference amplitude to place the peak of the carrier slightly above the top gratitude line. (d) Enable the “fine” amplitude adjustment. Set the carrier peak to exactly the yop of the reference line. (e) Read the displayed amplitude. (f) Repeat for the 243.0 MHz harmonic (C ...