Internal Duplexer Tray; Mds Sdm4-400 Mhz Notch-Type Duplexers - GE MDS Master Station Technical Manual

Supply does require first removing the supply input for the module, but the alternate Power Sup-
ply can remain powered. The unit will continue to operate using a single power supply.
When removing a Radio Module on a redundant unit, we recommend changing the selector
switch on the Alarm/Relay Module to lock the active radio to A or B as appropriate before re-
moving the other Radio Module. This should be done even if the desired radio is already active.
The manual override toggle switch is locking, and must be pulled out to change positions. Switch
functions are as follows:
- Up —Radio A;
- Down — Radio B;
- Center — Automatic.
Once a new Radio Module is installed, the Select Switch should be returned to the Center (Au-
tomatic) position for redundant operation.

Internal Duplexer Tray

The duplexer tray can be removed by first removing two screws on the top of the chassis holding
the tray in place. Save these screws. Disconnect all cabling to both the faceplate of the duplexer
and on the back of the unit. Once cabling and screws have been removed, push on the connectors
on the back of the unit to free the tray from the chassis and then slide out the front. To install a
new tray, slide the tray in allowing the connectors to push through the back of the chassis. Use
the same screws to secure the front of the tray to the chassis and then reconnect cabling being
careful to connect TX and RX cables from the Alarm Module to the correct faceplate connec-
tions on the Duplexer Tray.
MDS SDM4—400 MHz Notch-Type Duplexers
You can generally change the radio's transmit frequency up to 100 kHz without re-tuning the
duplexer. The duplexers shown in Figure 7-1. 400 MHz Notch Duplexer can be aligned in the
field by experienced technicians using high-quality test equipment. For assistance, contact GE
MDS Technical Support for additional details about tuning.
(Adjustment generally not required for transmit changes up to 100 kHz)
easily damaged if not handled carefully. It is highly recommended that you return du-
plexers needing realignment to GE MDS, or the original duplexer manufacturer, for
alignment. In some cases, it may be more economical to replace the unit than to have it
MDS 05-6399A01, Rev. E
Figure 7-1. 400 MHz Notch Duplexer
Duplexer alignment is a sophisticated procedure and a duplexer can be
MDS™ Master Station 95