Operating instructions

2-6 Overview
MB*/* Installation and Operation Manual
Port Locations
Five port plugs in the cover enable access to internal test points. The input and output ports
provide connection for coaxial cables and are protected by factory-inserted threaded plugs or
plastic cap plugs. Discard the plastic cap plugs when you install the cable connectors.
Figure 2-7 illustrates the housing port locations:
Figure 2-7
Housing ports
IN
13
24
Port 1 Port 2
Port 3 Port 4
Lid
Messenger
clamp bolts
Power Supply
The cover of the amplifier houses the model MPPS-II 60/90 power pack. It provides a regulated
24 Vdc output at 1.8 amps maximum over an ac input voltage range from 38 Vac to 90 Vac rms.
The input voltage waveshape is either a squarewave or a sinewave. The surge protector and the
EMI filter protect the power pack and amplifier from transient spikes. An integral fast-acting
zener diode provides additional surge protection.
The preregulator is a fixed frequency switching regulator that presents a near perfect power
factor to the input line and provides overvoltage and overcurrent protection. A precision output
regulator provides a precise output voltage and is also protected against overcurrent and short
circuits. If a short circuit is detected, the power supply shuts down and the regulator initiates a
sequence of line test pulses at approximately one-half second intervals. The regulator continues
these pulses for the duration of the short circuit but returns to normal operation when the fault
is cleared.