Broadcast Electronics FX-50, Instruction Manual

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©2011 Broadcast Electronics
6 POWER SUPPLY/CONTROL CIRCUIT
This section provides general information and specifications relative to the operation of the power
supply/control circuit board.
6.1 DESCRIPTION.
The control circuitry on the power supply/control circuit board regulates the operation of the RF amplifier within
preset limits depending on the forward power output, reflected power output, PA voltage and current, and RF
amplifier assembly temperature. The circuit board is designed with over temperature, over voltage, and short
circuit protection circuits, and a VSWR foldback circuit.
The power supply circuitry provides regulated dc potentials of +20V, -20V, and +5V required by all the exciter
circuit boards. An unreg30V dc potential is also provided by the power supply. Each power supply is
full-wave rectified, filtered, and electronically regulated to assure stable equipment operation.
6.2 ELECTRICAL CHARACTERISTICS.
Refer to Table 6-1 for electrical characteristics relative to the power supply/control circuit board.
Table 6-1. POWER SUPPLY/CONTROL CIRCUIT ELECTRICAL CHARACTERISTICS
PARAMETER SPECIFICATION
INPUTS
AC POWER REQUIREMENTS
FX-50 97 to 133V AC or 194 to 266V AC, 50/60 Hz,
230W Maximum
FX-50E 240V Nominal AC, 50/60 Hz, 230W Maximum
RF MUTE FROM TRANSMITTER
NEG POS LOGIC SWITCH
POSITION
POSITIVE 0V = RF mute
+5V = RF enable
NEGATIVE +5V or High Impedance = RF mute
0V = RF enable
EXTERNAL RF POWER CONTROL Positive potential, varies with adjustment of PWR
SET control R52. Nominally 0-6V DC with R52 fully
CW for 3-50W.
OUTPUTS
FWD POWER +11.45V at 10 K Ohm for 50W RF
RFL POWER Approxi1V at 10K Ohm for 2W RF
TEMP OL DRIVE +18V at 5 mA, Maximum
PA Voltage Approxi20.8V at 3.25 Amperes for 50W
RF.