User Manual

SECTION 1: THEORY OF OPERATION
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Exciter RF Section
Functional block diagram of the exciter RF section.
The exciter RF section generates the transmit RF carrier and accomplishes FM modulation. The VHF
signal from the VCO is applied to a buffer and is then routed to a divider network. The divider network
splits the RF signal into two (2) equal amplitude signals. One of these signals is used as the exciter
output; the other is sent back to the synthesizer as feedback for the PLL.
The frequency synthesizer divides the VHF signal to produce a quotient signal of 12.5 kHz. The
synthesizer also divides the signal from the 10.0 MHz reference oscillator to produce a 12.5 kHz signal.
The synthesizer compares the phase of these two (2) signals and outputs a signal (PD OUT) proportional
to their phase difference. A passive loop filter converts the PD OUT signal to a DC control voltage, which
locks the VCO on channel.
In this manner, the VCO is compared to - and forced to emulate - the high-stability reference oscillator.
This configuration is commonly referred to as a digital Phase-Locked-Loop (PLL) frequency synthesizer.
Power Amplifier Module
Functional diagram of the power amplifier.
The transmit injection signal from the RF injection section is applied to a one (1) watt amplifier. The
signal is then routed to the final power amplifier boosting the output signal to 60 Watts.
60 WATT
POWER AMPLIFIER
MODULE