4.7
Antenna LNB Replacement
The LNB assembly receives preamplifier operating power from
the IRD via the RF Detector PCB. Be certain that the IRD is
turned off or disconnected from its power source before
removing or reconnecting the LNB. The following sections
provide replacement instructions for both the European and
U.S.-style LNBs.
4.7.1 European LNB Replacement
1. Disconnect both RF coaxial connectors at the LNB.
Be sure to hold the cable at the connector’s base
while unscrewing.
2. Observe the currently set skew value, as marked
by the stickers on the LNB and choke assembly.
3. Loosen the wing screws and remove the LNB from
the choke assembly (as pictured in Figure 4-9).
4. Place the new LNB into the choke assembly.
Adjust the LNB’s position so that it has the same
skew value observed in Step 2.
5. Apply a small amount of thread-locking
compound (e.g., Loctite 425 or equivalent non-
permanent threadlocker) to the screw threads and
tighten the wing screws to secure the LNB in
position.
6. Reconnect the RF connectors. Be sure to hold the
cable at the connector’s base while fastening.
4.7.2 U.S.-style LNB Replacement
1. Disconnect both RF coaxial connectors at the LNB.
Be sure to hold the cable at the connector’s base
while unscrewing.
2. Loosen (2) wing screws on the throat of the choke
feed until the LNB is free to slide out. Withdraw
the LNB as pictured in Figure 4-10.
3. Insert the replacement LNB as far as it will go. Be
sure that it bottoms in the feedhorn. Be careful not
to puncture or dislodge the plastic seal covering
the LNB throat. Orient the LNB to align with the
strut holding the pair of RF cables.
4-11
Maintenance
54-0150 Rev. E
Figure 4-10
U.S.-style LNB Removal
Figure 4-9
European LNB Removal
