CPI S5CIA Installation And Operation Manual page 92

L B BUC O
AND PTION
The Local Oscillator reference can be supplied in one of three formats below:
• Multiplexed Local Oscillator reference frequency on the L-Band signal through the
type N RF input connector.
•
An internal LO reference integrated into the BUC.
•
An external LO reference through a separate BNC connector.
Multiplexed Reference: Most L-band modems now have a built-in 10 MHz reference. The CPI
BUC can be configured to accept this reference, which is multiplexed with the L-band signal on
the same connector. This is CPI's standard configuration, and it is recommended for most
applications. The level of 10 MHz should be +5 to -5 dBm at the amplifiers input.
Internal Reference: An internal 10MHz reference signal with ±1 ppm stability includes in the
BUC module. This oscillator performance is not as precise as a GPS reference, but it is adequate
for many applications.
External Reference: This allows the user to connect a system 10 MHz reference through a BNC
cable. This is used for systems that need to slave all amplifiers to a common timing reference,
such as the GPS signal. The level required is +5 to -5 dBm.
Notes:
•
Refer to the Drawing section of the respective Service manual for more information.
• Refer to the amplifier specifications in the documents section of this manual for
performance of the amplifier with a BUC.
Precautions:
• The modulator's gain should be adjusted for the best signal to noise ratio (-60dBc).
Adding fixed attenuators at the modulators' output can adjust the power level.
• A multiplexer should be used rather than a combiner. In case of using a combiner,
band pass filters should be added to modems' output or a 10 dB fixed attenuator can
be added to each combiner's input.
• Please take care to ensure that the proper L-band frequency range is not exceeded or
damage may result.
•
The L-band input signal must be free of the spurious signals that can cause poor
performance or even cause the amplifier to fail.
• The level of 10 MHz should be +5 to -5 dBm at the amplifiers input.
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