User's Manual

82 MDS Master Station MDS 05-6399A01, Rev. D
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.
Figure 7-1. 400 MHz Notch Duplexer
(Adjustment generally not required for transmit changes up to 100 kHz)
Duplexer alignment is a sophisticated procedure and a duplexer can
be easily damaged if not handled carefully. It is highly recommended
that you return duplexers 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 realigned.
MDS SDM9—Bandpass-Type Duplexers
These duplexers (Figure 7-2. 900 MHz Bandpass Duplexer
) typically allow the transmitter frequency to change up to 500 kHz without undesired results. Since this
type of duplexer cannot be re-aligned in the field, we recommend contacting the GE MDS Technical
Support Department if you suspect a duplexer problem or need one for a different frequency.
Figure 7-2. 900 MHz Bandpass Duplexer
(Adjustment generally not required for transmit changes up to 500 kHz)
POSSIBLE
EQUIPMENT
DAMAGE