Glenayre Document Number: 9110.00160
250-Watt Gold Line Power Amplifier
Issue 1, Rev. C: 10/21/96
THEORY OF OPERATION
Print Date: 12/17/96
Copyright © 1996 Glenayre
Page: 6-1
6
THEORY OF OPERATION
6.1
Power Distribution
The PA requires three separate power inputs: primary 25-volt dc power, secondary 13.5-
volt dc power, and fan 25-volt dc power. All power inputs are normally provided by the
Gold Line power supply.
6.1.1
Primary Power
Refer to
Figure 6-2
. Primary 25-volt dc operating power is received through the power
cables terminating with 1/4-inch ring lugs. The (-) input (black cable) is bolted directly to
PA chassis ground. The (+) input (red cable) is bolted to P1 on the metering board. P1
powers the +25V power bus on the metering board. This bus distributes primary power to
the metering board and to each common-base collector (CBC) power amplifier in the PA.
6.1.1.1
Metering Board +25V Signal Flow
Refer to
Figure 6-4
. +25 volts from the power bus is supplied through fuse F13 to these
places on the metering board: LED1, +25V components, divider circuitry, +5V regulator
and divider circuitry, and +1.2V regulator circuitry.
•
LED1 activates to illuminate the DC POWER indicator on the front of the PA.
•
+25V components receive operating power. These components include the current
detector amplifiers.
•
Divider circuit reduces the input to a sample voltage, which determines the PA 25V
metering.
•
+5V regulator/divider circuitry gen5V operating power for the metering board
+5V components. A portion of this +5V is reduced to a sample voltage, which deter-
mines the PA 5V metering.
•
+1.2V regulator circuitry generates the compensation voltage for the current detector
amplifiers.
6.1.1.2
Power Ampl25V Signal Flow
Refer to
Figure 6-1
. +25 volts operating power from the power bus is paralleled through
seven resistors. These resistors are a component of a current detection circuit.
Current-Detection Theory
Current-detection monitoring occurs on the metering board. The monitored current is
routed through a small resistor, resulting in a slight voltage drop across the resistor.
This voltage drop is amplified by a current detector amplifier, which generates an out-
put voltage proportional to the current flowing through the resistor. This output voltage
is the current sample for the monitored current.
