Instruction Manual

6X Series Liquid-Cooled Transmitter Chapter 4, Circuit Descriptions
Instruction Manual, Rev. 0 4-8
R33 and the output Balun assemblies to the drains of Q1 and Q2. The +42 VDC is also
connected through the 12V Zener diode CR1 to the regulator IC U4 that supplies +3.3
VDC, which is used by the U2, U6 and U7 ICs on the pallet.
4.3.6 (A17) 4 Way Combiner Board, Top (1310305)
The Top 4 way combiner board takes the four RF Inputs at J4, J5, J6 & J7
(≈225Watts ATSC) on the board 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, U2 takes the parameter sample inputs and supplies a serial data
output that is buffered by U1 before it is wired to the Serial Data Line connections at
J11-2 and J19-2. The Serial Data Line connects to the system controller for the
transmitter. U5 is not used in this configuration. R10 is a thermistor mounted to the
board, which generates a voltage reference of the temperature of the board that is
connected to the U2 microcontroller. The microcontroller generates a bit stream
sample of the reflected threshold level system setting that connects to the digital to
analog converter IC. The DAC IC generates a DC level that sets the reflected
threshold, which connects to the reflected fault comparator IC U10. J8 is a
programming port which is initially used to program the U2 microcontroller and is not
used by the customer. J12 is a programming port which is initially used to program
the U5 microcontroller and is not used by the customer.
The power detector portion of the board provides forward and reflected samples to the
U2 microcontroller. A Forward Output Power Sample connects to the board at J15.
The sample is split with one output connected to J8, the Forward Power Sample Jack,
located on the front panel and the other output filtered and split again. One output of
the splitter is connected to the detector IC U8, which produces an average forward
power DC level that connects to the microcontroller U2. The other output of the
splitter is connected to the detector IC U6, which produces an output that is fed to U7A
and U7B and associated circuitry. This circuit generates a peak forward power DC
level that connects to the microcontroller U2.
A Reflected Output Power Sample connects to the board at J17. The sample is filtered
and connected to the detector IC U9, which produces a reflected power DC level that
connects to the microcontroller U2. Another output of U9 is fed to a comparator IC
U10 that generates a reflected fault output if the input reflected level exceeds the
Fault threshold setting for the tray. The reflected fault output is wired to J18 that is
cabled to the phase/gain board where it connects to the fault protection circuitry.
Four 50Ω/120W terminations are mounted on the top combiner board for amplifier
pallets 1-4. The termination R34 connects at J14 to pallet 1, R15 at J9 to pallet 2, R23
at J10 to pallet 3 and R27 at J13 to pallet 4. The rest of the circuitry after the
terminations on the schematic is not used in this configuration.
+5 VDC is supplied to the top combiner board thru J11-3 & 1 from the bottom
combiner board. The regulator IC, U11, takes the +5 VDC input and generates the
regulated +3.3VDC that is used by the ICs on the board. The Green LED DS1 is lit if
the +3.3VDC is present on the board.
4.3.7 (A18) 4 Way Combiner Board, Bottom (1310308)
The Bottom 4 way combiner board takes the four RF Inputs at J4 from pallet 5, J5
from pallet 6, J6 from pallet 7 and J7 from pallet 8 (≈225Watts ATSC) on the board