Motorola XPR 8300 manual RF Antenna Connections, Duplexer Selection, Antenna Selection

Electrical Connections RF Antenna Connections 4-3

4.2RF Antenna Connections

The transmit and receive antenna RF connection are made using two separate connectors. Coaxial cables from the receive and transmit antenna must be connected to the Type-N (Tx) and BNC (Rx) connectors. The position of these connectors is shown in Figure 4-1. For repeater use, the antennas need adequate isolation between them, or if one antenna is used, the duplexer needs to have adequate isolation between the Tx and Rx ports. The isolation requirements are unique to each band and are shown in the table below:

Frequency Band	Bandwidth	Isolation
UHF 1	403–470 MHz	75 dB
UHF 2	450–512 MHz	85 dB
VHF	136–174 MHz	85 dB

If the duplexer isolation is not adequate, a preselector may also be used. See “Accessories” on page 6-1for a list of available duplexers and preselectors.

!	The repeater can key up at any time due to input from a subscriber unit or a
	CW ID. Please ensure that all power is switched off before disconnecting the
C a u t i o n	transmit antenna.

4.2.1Duplexer Selection

The selection of a duplexer is critical to system performance. The use of a notch (band reject) duplexer is possible in some systems that are not located at high RF density sites. See “Accessories” on page 6-1for a list of available duplexers.

The duplexer must be able to handle at least 50 W continuously. For the best system performance, the insertion loss should be less than 2 dB. If the repeater is used in higher RF density sites, the use of a pass-notch duplexer is recommended.

4.2.2Antenna Selection

The selection of the antenna is critical to system performance. The selected antenna must be

50 Ohm impedance and capable of at least 50 Watts. Gain antennas may be used to increase system coverage. Please take note of licensing restrictions when selecting gain antennas. Some services or regions may have antenna gain or system ERP limitations.

The antenna must be connected to the duplexer with a high grade 50 Ohm transmission line (hardline). The line must have connectors to match the connectors on the duplexer and antenna. For proper antenna installation, please also consult the Motorola Quality Standards Fixed Network Equipment Installation Manual R56 (6881089E50).

!It is important that all antenna cables are grounded at the point they enter the building.

C a u t i o n

!The antenna design is the customer's responsibility. All aspects of the antenna design must comply with the relevant local regulations.

C a u t i o n

6816814H01 March 2009