Function Of The Fan Module; Figure 11: Power Amplifier (Backplane Connections); Figure 12: Fan Module - Motorola ASTRO 25 GTR 8000 Manual

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

Figure 11: Power Amplifier (Backplane Connections)

2.1.3

Function of the Fan Module

The fan module provides intermittent forced-air cooling for the power amplifier and transceiver
modules. The fan module houses two 119 mm axial fans which deliver a total of approximately 160
cubic feet per minute of airflow. Nominal fan speed is 4100 revolutions per minute. A thermostat behind
the fan module controls each fan. If the fan speed for either fan falls below 30% of the rated speed, a
built-in speed sensor on each fan turns on the red Fan Alarm LED.
If the fan module is used for the Power Efficiency Package, the following must be configured in the
Configuration/Service Software (CSS) to take full advantage of the Power Efficiency Package:
• Optional fan holdover time (length of time the fan stays ON after transmission).
• Disabling one of the fans within the fan module. See
instructions on how to disable one of the fans.
• Configuring the base radios Tx Power Out in the CSS should be limited to 50 W.
The fan module connects to the backplane through a 4-pin port on the front of the chassis.
NOTICE: The power supply module has its own fan which provides independent airflow.

Figure 12: Fan Module

66
Replacing the Fan Assembly on page 237 for