Initial Operation Of The Modem With The Buc And Lnb - Comtech EF Data CDM-600L Installation And Operation Manual

CDM-600L Satellite Modem
DST Setup
TX Side Setup:
Step
No.
13. Disconnect BUC.
14. Determine the voltage required by the BUC and record for reference
15. Turn the BUC Power = ON and Verify the BUC Voltage is correct. The
voltage sent to the BUC is verified two ways per the next step.
16. The BUC voltage is reported under the Monitor Menu. Alternatively, the
BUC voltage can be measured at the center conductor of the transmit IF
connector. Use care to assure that the volt meter probe does not short to
the connector outer conductor.
To avoid damage to the BUC, confirm voltage matches the BUC voltage
requirement. (Typical Voltage is +24 or +48 VDC ± 5%)
17. To protect the equipment, select the BUC Power = OFF. This is necessary
before connecting the L-Band coaxial cables to the unit
18. Set the TX Terminal LO (MHz) and MIX (+ or -). The LO frequency is the
BUC local oscillator frequency and the MIX is.
Mix = "-" if the BUC LO > Satellite Frequency
Mix = "+" if the BUC LO < Satellite Frequency
19. Set Tx Spectrum Invert ON if MIX is "-".
20. Program the satellite frequency under the TX Terminal Frequency menu
21. Set the TX Power Level to a safe (low) value
22. Turn TX carrier to Off.
23. Connect BUC.
24. Turn BUC 10 MHz reference to ON.
25. Turn BUC power supply ON.
26. To automate warm up and delay carrier turn ON for a programmed delay
after prime power is applied see the BUC carrier output delay menu.
27. Record the nominal BUC current after the unit is warmed up and
functioning normally.
28. Set the High alarm about 20% higher than nominal
29. Set the Low alarm about 20% to 40% lower than nominal.
At this point, the unit will start transmitting when the TX-IF output is tuned On
(under Configuration: Tx: Tx-IF menu).
IMPORTANT
18.4

Initial Operation of the Modem with the BUC and LNB

The conditions for the LNB to function are:
Selection / Programming
Sufficient and correct DC power at the LNB
10 MHz reference supplied to the LNB for EXT REF units
18–5
Revision 2
MN/CDM600L.IOM
Menu Location
BUC
Monitor
BUC
BUC: More
Consult BUC manufacturer's
LO specifications.
Configuration:Tx:Tx-IF
Configuration:Tx:Tx-IF
Configuration: Tx:Tx-IF
Configuration: Tx:Tx-IF
BUC
BUC
BUC: MORE
Monitor: BUC
BUC
BUC