User's Manual

NTUM30DA Installation & Service Manual
4-4.3 Driver Amplifier
The driver amplifier consists of two stages of class AB amplification, which provide the approxi-
mately 40% of the gain in the 60 MHz frequency band from 1930 MHz to 1990 MHz.
4-4.4 Main Amplifier
The main amplifier employs two class AB amplification stages for maximum efficiency. It provides
approximately 40% of the gain in the 60 MHz frequency band. The output from the main amplifier
is typically higher than the rated output power of the MCPA, to allow for losses associated with
the components in the remaining RF path. The RF signals are then applied to a delay line and
directional coupler, where the distortion products are cancelled out and the amplifier power per-
formance is monitored.
4-4.5 Multifunction Board
The multifunction board consists of feed forward loop control and alarm circuits. The MCPA com-
municates to the host system through the multifunction board, which gathers the status informa-
tion of the amplifier and reports to the host system via the RS-485 interface when instructed. It
also protects the MCPA from adverse conditions such as overpower, input overdrive, over-
voltage, etc. A microprocessor on the multifunction board also controls two loops in the feed-
forward system.
Pre
Amp
Driver
Main
Amp
Error
Amp
Delay
Feed Forward Loop control
2nd Loop
Phase & Gain
1st Loop
Phase & Gain
Delay
Alarms & Display
+15 +5 -5
Power Supply
-30dB
-10dB
-40dB
RF Out
RFL
PWR
FWD
PWR
Front Panel
Smart Rack
+27VDC
Figure 4-1 NTUM30DA Multichannel Power Amplifier Functional Block Diagram
4-5 Amplifier Module Cooling
Each amplifier module is contained within a thermally conductive chassis and properly mounted
on an adequate thermal surface, which provides sufficient cooling when forced air is circulated
over the heat sink fins to maintain the amplifier within the specified operating temperature range.
 Copyright Powerwave Technologies, Inc., June 2003. All rights reserved
044-05141 Rev. A 4-2 June 2003