Broadcast Electronics Marti Electronics ME-40, Manual

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©2011 Broadcast Electronics
REQUIRED EQUIPMENT: A number 2 Phillips screwdriver with a 4 inch (10 16 cm) blade is
required to remove the power supply/control circuit board from the exciter chassis.
To remove the power supply/control circuit board, proceed as follows:
WARNING
DISCONNECT THE PRIMARY POWER TO THE EXCITER BEFORE PROCEEDING.
WARNING
a. Disconnect the primary power to the exciter.
b. Remove the exciter top-cover. Disconnect P10 and P11 from the circuit board.
c. Observe the orientation of P12 and P13 and disconnect from the circuit board.
d. Remove the screw near J11 securing the circuit board to the chassis.
e. With slight pressure, pull the circuit board from the mounting stud at each comer.
To install, follow the REMOVAL PROCEDURE in reverse order.
5.9.2
DETAILED THEORY OF OPERATION-Power Supply/Control Board
This section presents the theory of operation for the exciter power supply/control circuit board.
The power supply/control circuit board will be described as follows:
1) the control circuitry, and
2) the power supply circuitry
5.9.2.1
CONTROL CIRCUITRY
The control circuitry consists of five circuits. The following figure presents a simplified schematic
of the control circuits on the power supply/control circuit board. Refer to the figure as required
for a description of the following circuits.
•
RF Mute Circuit
•
Forward/Reflected Amplifier Circuits
• Temperature Sense Circuit
•
Open Fuse Detector Circuit
•
Power Control Circuit
1) RF MUTE CIRCUIT The RF mute circuit automatically inhibits exciter RF output if the AFC
circuit is unlocked or if the transmitter is not ready to accept RF drive. This circuit consists
of logic input switch S3, inverters Q3 and Q4, RF mute driver U3B, and mute switch Q2.