9/15/06
888-2586-001
4-15
WARNING: Disconnect primary power prior to servicing.
Section 4 Overall System Theory
Platinum Z16HD+
Each Z-Plane assembly contains:
•
Edge connectors for 8 PA amplifier boards (4 in front and 4 in the rear). These con-
nectors are labeled J1-J8.
•
An 8 way Wilkinson Divider, driven by the IPA, which feeds RF drive to each of the
8 PA amplifiers.
•
An 8 way Wilkinson Combiner that combines the output of the same 8 PA amplifiers.
•
ID jumpers to designate the Z-Plane for use as A, B, C or D. This prevents controller
cabling errors since the controllers check these IDs to verify proper connection.
•
Current Monitoring for each individual amplifier via R11-R18 on the Divider Board.
The actual current reading is the difference between the power supply voltage sample
labeled VD_#_VOLTAGE_SAMPLE and each individual
PA_#_CURRENT_SAMPLE (as labeled on the Divider Schematic).
•
Voltage inputs, E11 and E12, from 2 different power supplies such that 4 PAs are
powered from each supply. This voltage is also monitored and displayed in the Diag-
nostics screen. If this voltage goes too high or too low a PAC#_VOLTS fault will be
registered in the Fault Log. For detailed information on all transmitter faults refer to
Section VI, Troubleshooting.
•
The Divider Board is also the interface for interlock, temperature sense lines and the
PA_GATE voltages for the amplifiers.
The RF output of the Z-Plane board connects directly to the 3dB hybrid where it is
combined with the output of its companion Z-Plane. The Z-Plane boards are identical,
but the outputs connect to opposite ends of the 3dB hybrid (one at the top and one at the
bottom). This requires that one of the Z-Planes be physically inverted.
4.4.3.1
8-Way Divider
Refer to the Divider schematic for the following. Each 8-Way Divider is a 2-stage
Wilkinson divider. The 8 way dividers are located on the Z-plane boards in the center of
the PA assembly.
The input to the divider is first divided into two equal outputs at approximately 35 ohms
by a two-way Wilkinson divider with a 70.7 ohm isolation resistor, R9. Each of these
outputs (each end of R9) is then divided into 4 outputs in a 4-way Wilkinson divider.
The Wilkinson dividers contain isolation resistors which dissipate no power when all of
the outputs are correctly loaded, but if a PA is removed, resulting in an open-circuit on
an output, the Wilkinson circuit and the isolation resistors act to keep the input
impedance of the splitter near the nominal value of 50 ohms. Each output from each 4-
Way Divider is fed to the input of one PA Amplifier board via ports J1 - J8.
Summary of Contents for Platinum Z16HD+
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