TB8100 Service Manual Power Amplifier Circuit Description 121
© Tait Electronics Limited September 2006
7.2.3 Low Pass Filter and Directional Coupler Board
The output from the 60W board is fed to the RF output connector via a
low pass filter (LPF), to attenuate harmonics, and a dual directional coupler.
The directional coupler senses forward and reverse power which is rectified
and passed to the control circuitry for metering, alarm and power control.
The directional coupler is on the output side of the LPF to measure true
forward and reflected power.
7.2.4 Splitter and Combiner Boards
In the 100W PA the output from the 6W board is split through a 3dB
hybrid coupler on the splitter board to drive two 60W boards in quadrature.
The outputs from these two boards are then combined by another 3dB
hybrid coupler on the combiner board before being fed to the LPF/
directional coupler board.
7.2.5 Interconnect Boards
Because of the modular design of the PA, interconnect boards are used in
certain models to connect boards that are physically separated on the
heatsink. They have no components and their only function is to link two
parts of the circuit together. The interconnect boards are shown in
Figure 8.1 on page 130 and Figure 8.2 on page 131.
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