User's Manual

Innovator CHV400BTD ATSC Transmitter Board Descriptions
Technical Manual, Rev. 0 61
Circuit Descriptions of Boards in the CHV400, 400 Watt ATSC Amplifier Tray
(A7) Amplifier Control Board (1312260)
Amplifier Control Board
The Amplifier Control Board is mounted in the top front facing the rear of the Amplifier
Tray as shown above.
The Amplifier Control Board uses a Programmable logic device, U12, to control the
amplifier tray. It takes an enable signal from an external driver tray, and turns the
power supplies on whenever the driver has told it to turn on, unless it detects faults
internal to the tray. 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 tray 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 tray, through J4, so the information can be displayed on that tray'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 tray to see what fault has occurred.
A CHVB transmitter System can have up to 4 external amplifier trays and since they are
all the same, without differences in the wiring harness, there needs to be a way to
identify which amplifier tray 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 trays 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 CHV400 amplifier tray, there are two
sensing circuits which are used. In the CHV750 amplifier tray, 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
SW1