90
MDS 4790/9790 Series I/O Guide
MDS 05-3438A01, Rev. F
MDS 4790—400 MHz Notch-Type Duplexers
You can change the radio’s transmit frequency up to 100 kHz without
re-tuning the duplexer. The duplexers shown in
Figure 42
can be aligned
in the field by experienced technicians using high-quality test equip-
ment. For assistance, contact GE MDS Technical Support for additional
details about tuning.
Figure 42. 400 MHz Notch Duplexer
(No adjustment needed 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
re-alignment to GE MDS, or the original duplexer manufac-
turer, for alignment. In some cases, it may be more economical
to replace the unit than to have it re-aligned.
MDS 9790—Bandpass-Type Duplexers
These duplexers (
Figure 43
) 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 43. 900 MHz Bandpass Duplexer
(No adjustment needed for transmit changes up to 500 kHz)
CAUTION
POSSIBLE
EQUIPMENT
DAMAGE
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