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E. Output Filter
The output filter of the CLF5000/PLL performs two functions. The first is to provide low pass filtering to
the square -wave outputs of the power amplifiers to provide RF power with low harmonic components. The
second is to provide an effective 1/4 wave-length line section to effect a real-part impedance reversal to
provide a maximum output voltage when the load impedance is high. The input impedance to the filter is
about 4 ohms and the output is impedance is 50 ohms. The filter is made of 3 ‘L’ networks in series.
F. Power Monitor Board
The power monitor board (Figure FA0132RX) is a detector that produces voltages which are proportional
to actual delivered RF power, forward power, and reflected power. In addition, there is an output which
provides a relative indication of the phase relationship of the RF output voltage and current. The signal
from the delivered power detector is produced from current and voltage taps off the output line which are
multiplied with a four quadrant multiplier, U1 and buffered with U3A. Reflected power is derived by
summing a voltage tap with a current tap which is 180 degrees out of phase with the voltage tap. This
summed voltage is then squared with four-quadrant multiplier U2 and buffered with U3B. Forward power
is derived by s umming the delivered and reflected output signals via U3C. The phase detector is obtained
by driving a center-tapped current transformer with a voltage tap 90 degrees from the actual RF output
voltage and rectifying the 0 degree and 180 degree outputs of the current transformer. One side of the
current transformer is rectified to a positive polarity and the other side to a negative polarity. When these
two rectified signals are summed, the resulting output represents (bipolar) the phase relationship of the
actual RF output voltage and current. This summed signal is amplified and buffered with U3D.
VIII. Certification
This unit is designed and labeled in compliance with CE mark certification requirements. The manufacturer will
supply a Declaration of Conformity as required.
