Installation and Operating Manual

User Manual
040003A009 Rev D Page 3 of 25
1.2 PRODUCT DESCRIPTION
The Crescend Technologies High Power 900 MHz RF power amplifier is designed for paging and
other applications that use a single carrier constant envelope waveform. The amplifier is designed
to be powered from either an external +48 VDC source or an optional internal AC power supply.
The amplifier covers the 928-942 MHz band without retuning. Amplifier specifications are shown
in Table 1-1. There are seven input ranges available as shown in Table 1-2. Closed loop power
control is used to maintain a constant output power under varying voltage, signal input level,
frequency and output load conditions. Several design features work to protect the amplifier under
adverse conditions.
Output power level is controlled by power control loop. Control loop compares signal from forward
power detector, that is attached to directional coupler located behind final active RF stage, with
reference voltage, and adjusts attenuation of RF attenuator located on amplifier input. See block
diagram for details. Nominal output power level is factory calibrated. Output power level can be
reduced (below 250W) by operator (see page 17 of manual, Power Set Control.
The amplifier is designed to fit into 5.25 inches (3RU) of vertical 19 inch rack space. The front
panel includes LED indicators for monitoring status and alarm conditions. This information is also
accessible via a monitor connector on the rear of the amplifier. The fan assembly draws ambient
air in from the front and blows the air across the heat sink fins out the back of the amplifier.
NOTE: The manufacturer’s rated output power of this equipment (see Table 1-
1) is specified for single carrier operation using constant-envelope modulation. This equipment is
NOT designed for multiple-carrier operation, nor is it intended to be used with non-constant
envelope modulation waveforms. Table 1-1 Amplifier Specifications
Specification
Value
Instantaneous Bandwidth
928-942 MHz
Output Power Range
50 W - 250 W
Input Impedance
50 ohm
Output Impedance
50 ohm
Table 1-2 Amplifier Input Power Ranges
Input Power Designator Code
Input Power Range
Nominal Gain (250W Output)
R2
0.2 - 0.5 W
31.0 dB
R5
0.5 - 1 W
27.0 dB
1
1 - 2 W
24.0 dB
2
2- 5 W
21.0 dB
5
5 - 10 W
17.0 dB
10
10 - 20 W
14.0 dB
20
20 - 50 W
11.0 dB