Training, Installation & Service Manual - Livewire Connections Ltd

Removal and replacement of ADU modules
9.5.15 Replacing the Ortho Mode Transducer (OMT)
Figure 9-109: Ortho Mode Transducer (OMT)
The OMT interfaces a low-loss waveguide from the dual-polarized
feed-horn to the BUC/LNB.
The purpose of the OMT is to separate the TX and RX signals and
provide isolation between BUC and LNB. DC power, 10 MHz external
reference signal and a 22 kHz control signal is delivered via the IF
cable. The OMT uses the independency of the signals to split and
provide isolation. The OMT also detects the output power and
temperature of the BUC.
9.5.15.1 Removing the OMT
Tools needed:
• 4 x 150 mm Allen key
(located inside the
service door of the ADU)
• Torx20 screw driver
1. Follow the instructions in Removing the Polarisation Unit on
page 9-73.
2. Follow the instruction in Removing the LNB on page 9-80 and
remove both Co-pol LNB (to the left) and X-pol LNB (to the right).
9-82 Chapter 9: Service & maintenance 98-133966-E2