3-16.
FAULT DETECTION CIRCUITS
a. The fault detection system removes the RF drive from the klystron power amplifier if arcing or if an
excessive voltage standing wave ratio exists in the waveguide system.
b. The photocell will sense an arc in the output waveguide and will apply the signal to the arc detector.
The output of the arc detector will cause the diode switch to remove the RF drive from the klystron power
amplifier.
c. The reverse directional coupler samples the reflected energy in the waveguide. When the voltage
standing-wave ratio exceeds a predetermined value, the reflected power switch and the arc detector will cause the
RF drive to be removed from the klystron power amplifier.
Section IV. TRANSMITTER ANALYSIS
3-17.
TRANSMITTER INJECTION
Voltages used for transmitter injection can be considered as an additional subcarrier's output. The
frequencies will be mixed with the modulator's output in the translator portion of the transmitter to form the final
angle-modulated output signal.
3-18.
FREQUENCY GENERATOR SUBSYSTEM
communication station. All of the frequency outputs of this system are derived from a frequency standard. The
frequency standard produces an extremely accurate output signal which is continually monitored and compared
with appropriate frequency references. An error in the frequency standard's output can be corrected through
adjustments. The output of the frequency standard is coupled to the injection units through a synthesizer driver,
frequency synthesizers, and an injection patch panel (fig. 108). These simplified block diagrams represent the
techniques used in one particular station, but similar techniques will be used in other types of stations to develop
the required injection voltages.
a. The synthesizer driver, using the frequency standard's output signal, develops the fixed frequencies
needed to drive the frequency synthesizers. In this particular example, the synthesizer driver receives an input of
5 MHz from the frequency standard, divides it to 1 MHz, and develops 22 different output frequencies which are
used as the inputs to the frequency synthesizers.
b. The frequency synthesizers contain circuits which are capable of converting the relatively few (22)
fixed input frequencies into outputs that can be varied from 0.01 Hz to 50 MHz in selectable steps as low as 0.01
Hz. Frequency selections are made by the pushbuttons on the front panels of the frequency synthesizer units.
c. The transmitter injection units contain circuits which prepare the input signals for application to the
transmitter's translator circuits.
344 L3
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