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SECTION 4
PRINCIPLES OF OPERATION
4.1 INTRODUCTION
The following paragraphs provide information on the principles of operation of the converter.
4.2 FUNCTIONAL DESCRIPTION
The Multi-band block converters use a single-conversion frequency translation scheme. The
converters employ local oscillators that are phase locked to a 10 MHz reference source. All
converters can be operated from an external 5 MHz or 10 MHz reference source. The
reference oscillator will automatically detect the presence of an external reference and switch to
external reference source as long as the power level of the external source is above +1 dBm
nominal. The output from the internal reference oscillator is always 10 MHz. If a 5 MHz
external reference signal is applied, the internal reference source will frequency double the
incoming signal to achieve the 10 MHz output signal.
The RF local oscillator is a synthesized frequency-agile phase locked source.
4.2.1 DOWNCONVERTER FUNCTIONAL DESCRIPTION
The input signal is fed to an isolator and input filter which rejects out-of-band signals including
the image frequency. A coupler is used at the input to provide an RF signal monitor at the rear
panel of the converter. The signal is then converted in the first mixer to the IF frequency by use
of the RF local oscillator signal.
The output of the first mixer is fed to the output module. In the module a low noise amplifier is
followed by a PIN diode attenuator which provides gain control for the system, is amplified, and
output from the system.
