Instruction Manual
6X Series Liquid-Cooled Transmitter Chapter 4, Circuit Descriptions
Instruction Manual, Rev. 0 4-4
programming port which is initially used to program the U7 microcontroller and is not
used by the customer. J10 is the programming port which is initially used to
program the U9 microcontroller and is not used by the customer.
The fan power supply that uses the T1 transformer takes the +42 VDC input and
produces the +12 VDC output, which connects to the (A20) F1 Fan through Jack J1-2
& 1. The Fan 1 voltage, current and spin rate (Tach) are sampled and connected to
the PIC 1 microcontroller.
The fan power supply using the T2 transformer takes the +42 VDC input and
produces the +12 VDC output, that connects to the (A21) F2 Fan through Jack J3-2
& 1. The Fan 2 voltage, current and spin rate (Tach) are sampled and connected to
the PIC 2 microcontroller.
The pre driver power supply, that uses the T3 transformer, takes the +42 VDC and
produces the +32VDC needed to power the pre driver (Q6) that is located on the
Phase/Gain Board. The +32 VDC pre driver power supply voltage is sampled and
connected to the PIC 2 microcontroller.
R108 is a thermistor mounted on the fan power supply board, which generates a
voltage reference of the temperature of the board that is connected to the PIC 1 U7
microcontroller. The microcontroller takes this input and the Fan 1 information and
supplies a serial data output that is buffered by U8 before it is wired to the Serial
Data Line connections at J5-2, J6-2, J7-2 and J9-1.
4.3.2 Front Panel Smart Button Board (1310349)
The Button Board provides the front panel accessed push button switch which is
illuminated by multicolored LEDs. The switch lit Blue indicates normal operation.
When lit Red, indicates a malfunction has occurred. Pushing the button will cause
the front panel LCD on the system controller tray to display the operating
parameters of the selected power controller and/or the malfunction which has
occurred. J3 is the programming port which is used to initially program the
microcontroller and is not used by the customer.
4.3.3 (A2) Phase/Gain Board (1312011)
This board performs a variety of functions. It amplifies the incoming RF signal to the
amplifier tray, ≈15mW ATSC, to the level at the output of the board, ≈.6W ATSC,
which can drive the output stage of the tray to full power. It adjusts the phase shift
through the board so that parallel amplifiers combine correctly. The board also
contains protection circuitry to quickly mute RF drive in the event of an overdrive or
reflected power fault. It contains circuitry that controls and monitors the amplifier
tray. Finally, it contains DC/DC converters that generate various needed power
supply voltages for the board.
The RF input to the board at J3-A1, RF_RFIN, ≈15mW ATSC, is connected to the
directional coupler U20 which provides a sample of the signal. This sample is used to
drive the log amp detector U39 which measures the input level to the board. The
main RF signal, RF_U6, is then applied to a PIN diode attenuator consisting of CR9,
CR10, CR40, CR41 and U6. This attenuator is used to set the overall output level of
the tray. Increasing the voltage at TP2 will increase the gain of the tray.
The output of the PIN attenuator drives a high speed PIN switch consisting of CR7,
CR8 and associated components. This switch is used to remove RF drive quickly in