CPI 0102324500rR, Manual

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CHPA S
ERIES
E-2
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D
OC
.01023245 R
EV
.R
E.2 General Operation
The BUC converts the L-Band input frequency to the frequency required by the TWT through
adding the frequency of local oscillation (F
LO
) to the L-Band input frequency.
All BUC's require a reference signal to operate properly. This reference signal is typically
10MHz, however can be a different value. If the BUC F
LO
reference fails or drifts outside of the
capture range, a "BUC alarm" or "BUC fault" signal will be reported by the amplifier.
In the event that the BUC F
LO
becomes unlocked and a fault signal is reported the amplifier will
inhibit RF and shutdown HV to the TWT. A reset command will restore the amplifier to normal
operation once the fault is cleared.
The F
LO
reference can be supplied in one of the following three ways:
•
Multiplexed - F
LO
reference is multiplexed with the L-Band input signal.
•
Internal - F
LO
reference is generated internal to the BUC.
•
External - F
LO
reference through a dedicated reference port.
Caution: For multiplexed and external F
LO
reference BUC's, the L-band
input signal must be free of the spurious signals that can cause poor
performance. Spurious signals may also cause the amplifier to fail.
E.2.1 Multiplexed Reference
Most L-band modems now have a built-in 10 MHz reference. A multiplexed reference BUC is
configured to accept this reference multiplexed with the L-band input signal on the same
connector. This is CPI’s standard configuration and is recommended for most applications.
The level of the F
LO
reference should be +5 to -5 dBm at the amplifiers input.
Caution: Use a multiplexer rather than a combiner. If a combiner is used,
install a band pass filter to the output of the modem or add a 10 dB fixed
attenuator to the input of each combiner.
E.2.2 Internal Reference
An internal F
LO
reference signal with
±
1 ppm stability is included in the BUC. The oscillator
performance is not as precise as a GPS reference, but it is adequate for many applications.
E.2.3 External Reference
This allows the user to connect a system 10 MHz reference through a separate amplifier input.
The external reference is used for systems that need to slave all amplifiers to a common timing
reference, such as the GPS signal. The F
LO
reference level required is +5 to -5 dBm.