User's Guide

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External Filter Ports
SMA female connectors on the faceplate of the 48900 allow for connection of externally mounted
passive 50 Ohm filtering. The external filter then modifies the related passband. Should the
conditions change in the field, the external filter can be removed or replaced with minimal interruption
in service. RFS has a variety of filter options, see the application notes on our website of contact RFS
Applications Engineering for assistance. Separate ports are provided for both the uplink and
downlink.
Two jumpers are required to connect an external filter. One connector on the jumper must be an
SMA male to connect to the 48900; the other connector type will depend on the connector on the
filter. Ensure that the external filter is mounted close enough so that the jumpers will reach the
repeater without undue stress or crimping. Disconnect power from the repeater, then disconnect the
jumper from the uplink or downlink as needed. Connect the external filter and reconnect power to the
unit. The passband filter will modify the passband of the link.
Installation
§ Choose an optimal location.
The choice of a location for the 48900 to reside is often dictated by circumstance. These units
can withstand a wide range of environmental conditions, but a cooler environment will increase
the life of the product. The 48900s are not intended for outdoor operation without protection.
Furthermore, a stacking room near a riser for easy access to the roof and other floors is desired.
However, access to clean 110/220 VAC power is the only requirement.
§ Install directional donor antenna and align with desired base site.
Yagis, corner reflectors and panel antennas work best. The 48900s have sufficient filtering to
prevent undesired signals from causing interference; however, it is best to reduce the chance for
interference by directing the mobile signals only towards the desired base site.
§ Check the incoming signal before connecting.
The product will work with a wide range of RF input signal levels. Ideal levels on the downlink are
in the range of -60 dBm. These levels will provide a maximum output power while not causing
significant overdrive. Also, check for extremely strong out-of-band signals. These may overdrive
the filtering and cause gain reduction.
§ Connect the donor antenna to the 48900 via a 50-ohm coaxial cable.
Size and type of cable are a matter of choice. Typically, 1/2" Flexwell foam coax is used, plenum
rated for inside buildings and work areas. However, 7/8" cable may be used to reduce
longitudinal loss. Superflex cables are easier to install but have higher longitudinal loss.
WARNING
Do not connect AC power until antennas have been connected to both the base and
service area ports.