User's Manual

044-05156 Rev C 24
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.
4.5.3 Intermodulation
The G3S-1900-125 amplifier is designed to deliver a 125-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.
4.5.3.1 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 -63 dBc
4.5.3.2 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 -63 dBc or better.
4.5.4 Amplifier Monitoring
The amplifier has a separate remote alarm and control connector, which may be used by the host system to
monitor and control the individual amplifier modules. The status, alarm, control, and power connections on the
amplifier connector are made through a 21-pin male D-Sub combo connector and are listed and described in the
Amplifier Module DC and Logic Connector Definition table.
A1
A2
A3
A4
1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17
DC and Logic Connector (Male, on Rear of G3S-1900-125 Amplifier Module]
Amplifier Module DC and Logic Connector Definition
PIN Function Description
A1 Power Input +27 Vdc (Power Contact)
A2 Power Input +27 Vdc (Power Contact)
A3 Ground Ground (Power Contact)
A4 Ground Ground (Power Contact)
1 RS485 +TxD Serial Communication Data Out
2 RS485 +RxD Serial Communication Data In
3 Service Loop TTL input to Amp. Gnd. for special test mode (Note 1)
4 MCPA Disabled
(Summary Fault)
TTL signal normally low indicates MCPA enabled. A high level indicates that the MCPA has
been disabled. Over Power, Over Voltage takes one second to activate the signal.
5 Mod Addr 0 TTL input to Amp. Gnd. supplied by shelf to identify slot.
6 Mod Addr 1 TTL input to Amp. Gnd. supplied by shelf to identify slot.
7 TP1 TTL output. Future test point.
8 Manual Download GND to download manually
9 DC on stat TTL output. High indicates Amp is powered on.
10 RS485 –TxD Serial Communication Data Out
11 RS485 –RxD Serial Communication Data In
12 SCL7 No connection
13 SDA7 No connection
14 FP Disable Output Output, GND if the front panel switch is in the OFF position; +5 volts indicates the front panel
switch is in the ON position.
15 FP RST Output, GND if the front panel switch is in the RESET position; +5 volts otherwise.
16 GND Ground
17 Module Detect Ground potential. Informs the subrack that an MCPA is plugged in.