User's Manual

Innovator CU0TD-1/CU0RD-1 – CU4TD/CU4RD ATSC Board Descriptions
Transmitter/Regenerative Translator
Instruction Manual, Rev. 2 117
The Amplifier Control Board uses a Programmable logic device, U12, to control the
amplifier drawer. It takes an enable signal from an external driver drawer, and turns the
power supplies on whenever the driver has told it to turn on, unless it detects faults
internal to the drawer. The board monitors the forward and reflected power, the heatsink
temperature, the pallet currents, and the power supply voltage and will generate alarm
signals if any of those parameters exceed safe limits. The amplifier drawer has no front
panel display other than a two LEDs, one for Status and one for Enable. The board sends
all its output information, including the forward and reflected levels, back to the driver
drawer, through J4, so the information can be displayed on that drawer's LCD Display.
The board will generate a Red Blinking Status LED if it detects an alarm, fault, prompting
the operator to look at the LCD display on the driver drawer to see what fault has
occurred.
A CUB transmitter System can have up to 4 external amplifier drawers and since they are
all the same, without differences in the wiring harness, there needs to be a way to identify
which amplifier drawer is which. The rotary switch SW1 is used to specify the amplifier ID
number which generates a unique serial address so that the individual amplifier drawers
will respond when polled for information.
The +5 VDC inputs to this board are routed through J4-8 and J5-8. The +5 VDC inputs
are diode Or connected so that either the +5VDC from the (A8) power supply or the
+5VDC from the (A9) power supply will operate the board. The +5VDC is split with one
output connected to U1 a voltage regulator IC, which provides +5V and +5V_ANALOG as
outputs. The +5 VDC is filtered before being connected to the rest of the board. The
other +5 VDC output is connected to the regulator IC U2 that supplies +3.3 V to the
microcontroller and programmable logic array.
(A10) Current Metering Board (1309130)
The current metering board measures the current into the RF output amplifier pallets
and supplies this value to the control board. In the single pallet amplifier drawer, there
are two sensing circuits which are used. In the multiple pallet amplifier drawer, there
are four sensing circuits which are used. Each circuit has two parallel .01Ω series
current sensing resistors and a differential input IC that supplies a voltage output that is
proportional to the current for metering purposes. The +42VDC from the (A8) power
supply connects to TB2 and TB4 on the board. The +42VDC from the (A9) power supply
connects to TB8 and TB10 on the board. The +42VDC input at the TB2 input senses the
current to the (A1) 878 output amplifier pallet through TB1 on the board. The +42VDC
input at the TB4 input senses the current to the (A2) 878 output amplifier pallet through
TB3 on the board. The +42VDC input at the TB8 input senses the current to the (A3)
878 output amplifier pallet through TB7 on the board. The +42VDC input at the TB10
input senses the current to the (A4) 878 output amplifier pallet through TB9 on the
board.
The two or four sensing circuits are identical therefore only one will be described. For
the (A1) 878 amplifier pallet, the +42VDC from the (A8) switching power supply
connects to TB2. R1 and R2 are the parallel .01Ω current sensing resistors which
supplies the voltage values to the U1 current sense amplifier IC. R11 is a gain adjust,
which is adjusted to eliminate any rSense Error and to place the OpAmp output at 2.61V
for 40Amps sense as measured at TP3. The current sense output at J1-1 connects to
the (A7) control board for metering purposes.