Page 9
FiberLink 1900 Series User’s Manual
FiberLink 1900 Series
Transmit
LED/LD
IRIG
Output
Installation Procedure
The FiberLink XA-1900 is supplied pre-aligned for use with an input signal of 1 volt rms . It
may be put into service by simply making the appropriate signal and power connections .
When input voltages in excess of the normal 1 volt rms level are to be accommodated, the
following procedure (in particular, steps 2, 3, and 4) should be followed:
1 . It will be necessary to have a source of +15 to +25 volts DC or 14 to 18 volts AC 50/60
Hz . Be certain to make all connections carefully and check that the correct pins are
being used .
2 . Turn the input attenuator , located in the white plastic bushing between the electrical
connectors on the XA-1900, fully clockwise (10 - 15 turns will be (adequate) . In the
XA-1903, this attenuator is located on the internal P/C board, near the input BNC
connector, and is labeled R1 . When using the XA-1903, also set the rear panel input
switch to the 600 ohm position .
3 . Apply power and, with no signal applied, connect an oscilloscope between the test
jack, located next to the optical output connector and the case of transmitter for the
XA-1900, and on the P/C board for the XA-1903 . Any of the points labeled TP1, TP2,
TP3, TP4 or TP5 may be used . The oscilloscope will show the current flowing through
the transmitting LED, which exactly corresponds to the signal being transmitted .
4 . Apply the signal to be transmitted and slowly turn the attenuator until the signal
appears on the scope . Now continue to turn the attenuator until a maximum
peak-to-peak amplitude of 0 .8 volts is obtained . This point constitutes full modulation .
If the signal level is increased further, distortion and clipping will occur . The best level
is just below the clipping point .
5 . Once this adjustment has been made, the transmitter is ready for operation .
Installation of XA-1900 and RA-1900 in the 6000A Card Cage
The 6000A rack-mountable chassis is a 20 slot, 3RU chassis . The XA-1900 and RA-1900 are
available in card versions that fit the 6000A rackmount chassis . The adjustment Potentiom-
eters are located on the front of the XA-1900 and RA-1900 cards .
The XA-1900 and RA-1900 cards take advantage of the Alarm function of the 6000A chassis
when using the 6020A ALARM Card . To activate the ALARM function, locate the ALARM
switch on the printed circuit board and set Position 1 to ON . The transmitter ALARM func-
tion will detect loss of input signal . The receiver ALARM function will detect loss of signal or
loss of optical input .
Installation Instructions for XA-1900 and XA-1903
