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User Manual
Rev. 1.2 - 21/01/11
TEX2000LCD
• Clipper (limits modulating signal level so that frequency deviation never exceeds
75kHz)
• Modulating signal measurement.
8.4.2 PLL/VCO section
This section of the board generates the modulated radiofrequency signal. It is
based on a PLL architecture that includes an MB15E06 integrated circuit.
8.5 Driver Board (SL176DR1001)
This section accommodates a BLF177 transistor that preamplifies the RF signal
before it is relayed to the final power amplifier. When the exciter is placed into
stand-by mode, the driver is inhibited, too.
8.6 Power Amplifier
The RF power amplification section consists in four power modules coupled through
a Wilkinson splitter and combiner using strip-line technology.
Each RF module provides 500 W rated power using a single active element built
using MOS technology. RF modules are fed by the switching power supply via
the Bias board.
The splitter (Splitter Board code SL176SP1001) splits the incoming power
input signal equally to all RF modules. The combiner (Combiner Board code
SL176CM1001) combines the power output signals available at module outputs
to obtain total amplifier power.
Splitter, amplifiers and combiner have been designed to sum amplifier output power
signals in phase, so as to keep unbalance and power dissipation to a minimum.
The whole RF section is mounted on a finned heat sink with fan cooling.
8.7 LPF Board (SLLPFTEX1KL)
This board incorporates a low-pass filter to keep amplifier harmonics within
permissible limits as specified by international standards.
A directional coupler is provided at filter output to measure forward and reflected
RF output power; power readings are relayed to the Interface and Bias boards to
enable processing and display.
The LPF board incorporates an RF output (having a level about -60 dB lower than
output level) which is brought to a BNC connector (figure 6.2 - [20]). This provides
a convenient test point to check carrier characteristics, but does not ensure
accurate assessment of higher harmonics.
