Comtech EF Data VMS v3.12.x Vipersat - Manual (Page 288)

Devices MN/22156, rev 12
4-70 VMS User Guide
Figure 4-44 Block Up Converter dialog, CDM-840
The 10 MHz Reference setting provides the option of having the Remote unit
supply an external reference for the BUC LO to maintain the correct transmit
frequency.
If this unit will be providing power for the BUC, select Output Power Enable,
then set the Low and High Current threshold Alarm Limits (0–4000 mA).