Specifications

H.10 Output Sample Board
H.11 Introduction
This Section describes the Output Sample board. Topics include
function, location, detailed circuit description, troubleshooting,
and removal/replacement.
H.12 Location
The Output Sample board is located in the Output Network
Cabinet toward the top of the compartment (SEE VIEW 19).
NOTE: Parts List for this board is in Section VII.
H.13 Function
The Output Sample board includes current sample and voltage
sample circuits for VSWR fault phase angle detectors and the
power meter’s directional couplers.
H.14 Detailed Circuit Description
H.14.1 RF Current Samples
H.14.1.1 VSWR Phase Angle RF Current Sample
The current sample for the phaseangle detector includes a current
transformer, with the copper rod carrying the RF current as the
primary, and a toroid or ferrite core inductor, T1, as the secon-
dary. Resistors are connected across the secondary to load the
winding and to convert the current sample in the secondary
winding to a voltage sample for the phase angle detector.
H.14.1.2 Directional Coupler Current Sample
The current sample for the directional coupler comes from cur-
rent transformer T2 on the Output Sample board. The current
transformer’s primary winding is the copper tube in the output
network. Resistors R10 through R17 convert the current into two
RF voltages, 180° out of phase with each other, and also load the
winding to prevent the high voltages that would appear across
the unloaded winding. The 2 voltages are used as the Forward
and Reflected samples for the Directional Coupler.
H.14.2
RF Voltage Samples
H.14.2.1 Forward Voltage Sample
The Forward Voltage Sample is taken from a capacitive divider
made up of capacitors, C7, C14, C11 AND C15. It is sent to the
Output Monitor board via J1, and will be used for the Forward
Power meter reading.
H.14.2.2 Reflected Voltage Sample
The Reflected Voltage Sample is taken from a capacitive divider
made up of capacitors, C7, C13, C10 and C16. It is sent to the
Output Monitor board via J1, and will be used for the Reflected
Power meter reading.
H.14.2.3 Antenna VSWR Voltage Sample
The Antenna VSWR Voltage Sample is taken from a capacitive
divider made up of capacitors, C7, C12, C9 and C17. It is sent to
the Output Monitor board, via J1-11, where it will be used by the
Antenna VSWR Sense circuit.
H.14.2.4 Network Voltage Sample
The Network Voltage Sample is taken from a Capacitive voltage
dividermade up of C7, C8, and C9, all three of which are attached
to the RF input of the Output Network, and another C8, which is
on the Output Sample board. It is sent to the Output Monitor
board, via J2 where it will be used as part of the Network VSWR
Sense circuits.
H.15 Troubleshooting
Troubleshooting this board would mainly involve a visual in-
spection looking for a cracked toroid, open or broken capacitor,
or a loose connection.
H.16 Removal and Replacement
WARNING
ENSURE THAT THE TRANSMITTER IS TURNED OFF AND ALL
PRIMARY POWER IS TURNED OFF AT THE WALL DISCONNECT
SWITCH BEFORE OPENING ANY DOOR OR PANEL. BEFORE
REMOVING PANELS OR OPENING DOORS, VERIFY THAT THE
RF AMP POWER SUPPLY IS DISCHARGED BY CHECKING
“PA+VDC” ON THE FRONT PANEL MULTIMETER. USE A VOLT-
METER TO VERIFY THE POWER SUPPLIES HAVE BEEN DIS-
CHARGED PRIOR TO TOUCHING ANY COMPONENTS.
a. Remove the connectors.
b. Remove the copper tube running through the Sample
board.
c. Remove the 4 mounting screws. Reverse this procedure for
installing the replacement.
H.17 Alignments
There are no alignments available on this board.
02/17/04 888-2339-002 H-11
WARNING: Disconnect primary power prior to servicing.