Comtech EF Data KST-2000A, Инструкция по установке и эксплуатации

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Ku-Band Satellite Transceiver Revision 9
Operation MN/KST2000AB.IOM
3–27
3.10 L-Band to IF Down Converter Description (KST-2000A/B)
The L-Band to IF down converter (Figure 3-17) accepts an RF input in the frequency
range of 950 to 1700 MHz and translates it to an output of 70 (140) MHz. The RF input
to this module can be supplied by the Ku to L-Band down converter housed within the
KST-2000A, or from an externally mounted Low Noise Block down converter (LNB) in
the KST-2000B version. Interface circuitry is added to this module for the
KST-2000B in addition to an L-Band monitor coupler as shown by the dotted lines in
Figure 3-13.
950-1700
MHZ
72 MHZ
REF
70/140
MHZ
720 (70)
790 (140)
1.6-2.35
GHZ
0-20 dB STEP
ATTENUATOR
INTERFACE
L-BAND
MONITOR
Figure 3-13. L-Band to IF Down Converter Block Diagram
The 950 to 1700 MHz input is first pre-selected and then heterodyned with a local oscil-
lator in the range of 1.6 to 2.35 GHz to generate the first IF signal of 650 MHz. The 650
MHz signal is then mixed with 790 or 720 MHz to generate the 70 or 140 MHz output.
The IF output frequency of the second down conversion stage is then amplified and ap-
plied to a 0 to 20 dB step attenuator with 1 dB steps. The overall L-Band down converter
tunes in a frequency step-size of 1 MHz across the 950 to 1700 MHz band.
This module is slightly different for the 70 and 140 MHz options.