7
Operating Pointers
Driving Signal:
The input to the XA-1900 is an AC coupled 600 ohm
impedance. It can be driven by any source including lines
with DC levels (below 4 volts) present. The signal return is
connected to case ground and power ground.
The XA-1903 may be switched between the 600 ohm
impedance level and a high impedance level. The high
impedance level is used to connect additional XA-1903 units
to form a distribution system. When this feature is desired,
connect the original IRIG signal to the input BNC connector
of the first XA-1903 and the output BNC connector of that
unit to the input BNC connector of the second XA-1903 and
so on until all XA-1903 units have been connected. Then set
all impedance switches to the high impedance position except
for the last XA-1903, which should be set for 600 ohms.
Power Supplies:
The power input to the XA-1900 is designed to accept AC or
DC voltages. In order for proper operation, the AC level
should not drop below 14 volts rms or the DC level, below 15
volts DC. As long as this criteria is met, unregulated sources
may be used. To prevent damage, voltages higher than 18
volts AC or 25 volts DC should not be applied. Suitable
voltages can be obtained from various low voltage
transformers or from a Fiberlink XP-1000A, 115 to 14
VAC plug-in adapter.
Note that one side of the DC input or AC input is connected to
the case.
The XA-1903 operates from 115/239 VAC 50/60 Hz.
Optical Fiber:
Versions of the XA-1900 and XA-1903 are available to drive
most multimode (MM) and single-mode (SM) optical fibers.
The specific models are identified by a suffix at the end of the
model number as follows:
10
Operating Pointers
Output Signal:
The output of the RA-1900 and XR-1900 is designed to drive
load impedances of 600 ohms or more. The RA-1900
employs an unbalanced output configuration with signal return
connected to case ground and power ground. Attempting to
drive lower impedance loads may result in distortion and low
output levels.
Power Supplies:
The power supply considerations for the RA-1900 and
XR-1900 are the same as for the XA-1900.
Optical Fiber:
Versions of the RA-1900 and XR-1900 are available to drive
most multimode (MM) and single-mode (SM) optical fibers.
The specific models are identified by a suffix at the end of the
model number as follows:
Fiber Size
Connector
850nm
1300nm
50u, 62.5u MM
ST
-1
-3
50u, 62.5u MM
SMA
-2
-4
8/10u SM
FCPC
-
-7
Installation of RA-1900 in the MCR-1000A Card Cage
The RA-1900 can be used in the MCR-1000A rack-mountable card cage. In
order to accomplish this, it must first be mounted to an AP-1000 adapter plates
with the four enclosed nylon binder head screws. Then the 5 pin power
connector and BNC signal cable on the adapter plate must be connected. When
this is done, the unit is ready to be plugged into the card cage. All operating
power for the RA-1900 will then be provided by the MCR-1000A card cage.
