Rfds - External Dual Circulator/Isolator Tray (Vhf); Antenna Relay Module; Figure 24: External Dual Circulator/Isolator Tray (Uhf) - Motorola ASTRO 25 GTR 8000 Manual

MN003286A01-E
Chapter 2: GTR 8000 Base Radio Theory of Operation

Figure 24: External Dual Circulator/Isolator Tray (UHF)

2.3.10

RFDS - External Dual Circulator/Isolator Tray (VHF)

An option for the GTR 8000 Base Radio is an External Dual Circulator module which isolates the base
radio from the antenna, thus preventing the transmitter from generating intermodulation. The circulator
load dissipates reflected power. It includes a cable that connects to the RF Peripherals port on the
base radio backplane to provide temperature monitoring.
2.3.11

Antenna Relay Module

The antenna relay module allows a single antenna to be used for both transmit and receive functions
on a conventional GTR 8000 Base Radio. A signal from the base radio transceiver module controls the
antenna relay module. The antenna relay module is typically mounted on the backplane cover on the
rear of the base radio, or on the peripheral tray if the base radio is equipped with other options.
25: Antenna Relay Module Connections on page 77
external connections. Settings for the antenna relay module are made through Configuration/Service
Software (CSS) and UNC.
NOTICE: If the antenna relay is Enabled and it is then disconnected, a failure is generated and
logged stating the antenna relay is disconnected. However, the base radio also generates an
exciter failure because the antenna relay is controlled and monitored through the exciter
module. The exciter failure should be ignored until after the antenna relay failure is corrected.
The failures are reported in the Status Report and UEM.
76
shows the antenna relay module input and output
Figure