User's Manual

044-05077 Rev. A
4-4
range of the loop control, a loop fault will occur. The alarms are displayed on the front panel
indicators and output via a 21-pin connector on the rear of the module to the subrack summary
board for subsequent remote monitoring via the ALARMS connector. Refer to paragraph 2-5.1 as
well as figure 2-2 and table 2-1 for a description of the ALARMS connector.
4-5.4. AMPLIFIER MODULE COOLING
Although each amplifier module contains its own heat sink, it is cooled with forced air. Four fans
are used for forced air cooling and redundancy. The fans, located on the front and rear of the
amplifier module, draw air in through the front of the amplifier and exhaust hot air out the back of
the module. The fans are field replaceable.
4-6. POWER DISTRIBUTION
Primary DC power for the system is provided by the host system to the MCR2200 Series subrack.
The subrack supplies each amplifier module with +27 Vdc directly and via the RF power
splitter/combiner. The amplifier module has a DC/DC converter that converts the +27 Vdc to +15
Vdc, +5 Vdc and -5 Vdc.
4-7. INTERMODULATION
The G3S-1900-80 amplifier is designed to deliver a 80-watt composite average power, multicarrier
signal, occupying a bandwidth less than or equal to 20 MHz, in the bandwidth from 1930 to 1990
MHz. The maximum average power for linear operation, and thus the amplifier efficiency, will
depend on the type of signal amplified.
4-7.1 TWO TONE INTERMODULATION
When measured with two equal CW tones spaced anywhere from 30 kHz to 20 MHz apart, and at
any power level up to the average power, the third order intermodulation products will be below
-65 dBc
4-7.2 MULTITONE INTERMODULATION
Adding more tones to the signal will lower individual intermodulation products. If the frequencies
are not equally spaced, the level of intermodulation products gets very low. When the frequencies
are equally spaced, those products fall on top of each other on the same frequency grid. The
average power of all intermodulation beats falling on the same frequency is called the composite
intermodulation; it is -65 dBc or better.
4-8. ALARMS
The presence of several plug-in amplifier alarms can be detected at the DC and logic connector on
the amplifier rear panel. Refer to table 2-1 and figure 2-2 for a description of the connector.