Comtech EF Data CDM-600/600L - Manual (Page 269)

CDM-600/600L Open Network Satellite Modem Revision 3
Appendix H MN/CDM600L.IOM
H–5
H.6 Initial Operation of the Modem with the BUC and LNB
The conditions for the LNB to function are as follows:
• Sufficient and correct DC power at the LNB.
• 10 MHz reference supplied to the LNB for EXT REF units.
H.6.1 RX Side Setup
Step Procedure
Front Panel Menu
Reference
30 Disconnect LNB. N/A
31 Set the RX Terminal LO (MHz) and MIX (+ or -).
The LO frequency is the BUC local oscillator frequency;
Mix = “-” if the LNB LO > Satellite Frequency
Mix = “+” if the LNB LO < Satellite Frequency LNB: MORE
Consult LNB
manufacturer’s
specifications for LO
32 Set Demod Spectrum Invert ON if LNB mix is “-“. CONFIG: RX Æ RX-IF
33 Program the satellite frequency under the Rx Terminal
Frequency menu CONFIG: RX Æ RX-IF
34 Select 10 MHz Ref = ON (if LNB is external reference unit) LNB
35 Program LNB Voltage to the correct value (13, 18, or 24
VDC) LNB
36 LNB Voltage OFF. LNB
37 Connect LNB. N/A
38 Program LNB Power = ON LNB
39 Record the nominal LNB current after the units are warmed
up and functioning normally. MONITOR: LNB
40 Set the High alarm about 20% higher than nominal. LNB
41 Set the Low alarm about 20% to 40% lower than nominal. LNB