Motorola SG4-DRT-2X Instruções de Operação descarregar pdf (Página 82)

4-10 Modules

SG4000 Installation and Operation Manual

SG4000 RF Module

Each SG4-RF module contains the entire necessary forward and return path circuitry for each

individual port within the SG4000 node. All diplex filtering in the node is achieved within the

RF module by means of the main diplex filter and a Vertical Return Path Low Pass Filter

(V-RPLPF) designed to further reject forward energy from the transmitter input. AC power

passing and fuses have been removed from the RF module. These functions are handled by the

port entry boards at each port location.

The RF connections from the respective forward and return configuration boards are made

through SMB connectors on the top of the module. The silkscreen chassis cover is color coded;

red represents the return path and black is the forward signal path. The RF cables have

corresponding color codes to help you during installation. The forward path contains a JXP

location for gain adjustments, followed by a Flatness and Slope Board (FSB) that contains

response correction and slope circuitry. You can replace the standard FSB with a low or high

slope version to customize the slope of a particular node port.

Following the FSB board is a Motorola proprietary Enhanced Gallium Arsenide (E-GaAs) hybrid

amplifier. Beyond the hybrid is the diplex filter and forward –20 dB RF test point. This test

point is also accessible through the housing when the RF module is in one of the four corners of

the node.

A -20dB test point follows the diplex filter in the return path. Beyond the test point is a JXP

location to make return path gain adjustments prior to the transmitter.

The SG4-RF module is equipped with special drive circuitry that provides thermal

compensation eliminating the need for you to make any set-up adjustments or gain set backs.

The RF module connects to the port entry board by means of a “G” connector on the bottom of

the RF module.

Figure 4-6 illustrates a block diagram of the SG4-RF module.

Figure 4-6

SG4-RF module block diagram

JXP

LPF

TP (-20 dB)

JXP

Slope

ICS

TP (-20 dB)

TP -20 dB Ext.

1 2 ... 77 78 79 80 81 82 83 84 85 86 87 ... 107 108

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Motorola SG4-DRT-2X Instruções de Operação Página 82