Instruction Manual

6X Series Liquid-Cooled Transmitter Chapter 4, Circuit Descriptions
Instruction Manual, Rev. 0 4-9
and combines them into a single output (≈750Watts) at J2 on the board which is
cabled to one input of the Power Combiner.
The microcontroller, U5 takes the parameter sample inputs and supplies a serial data
output that is buffered by U4 before it is wired to the Serial Data Line connections at
J11-2 and J15-2. The Serial Data Line connects to the system controller for the
transmitter. R36 is a thermistor mounted to the board, which generates a voltage
reference of the temperature of the board that is connected to the U5
microcontroller.
Four 50Ω/120W terminations are mounted on the bottom combiner board for amplifier
pallets 5-8. The termination R27 connects at J13 to pallet 5, R23 at J10 to pallet 6,
R15 at J9 to pallet 7 and R34 at J14 to pallet 8. The rest of the circuitry after the
terminations on the schematic is not used in this configuration.
+5 VDC is supplied to the bottom combiner board thru J11-3 & 1 from the fan power
supply board. The +5 VDC is split and one part connected to the top combiner board
thru J15-2 & 1. The other +5 VDC connects through rectifier diodes CR5 and CR6
which drop the voltage to +3.3 VDC whose output level is maintained by C14. The
+3.3VDC is used by the ICs U4 and U5. The Green LED DS1 is lit if the +3.3VDC is
present on the board.
4.3.8 (A19) Power Combiner (1312281)
The Power Combiner takes the outputs of the top (≈750Watts ATSC) and bottom
(≈750Watts ATSC) combiners and combines them to a single output (≈1.5 kW
ATSC) which is the output of the power amplifier tray.