Operating Instructions
Model 2809
CATV
Linx
®
LDS CATV Receiver
12
Revision 1.0
certain that the fiber is the proper size. This product can only be used with sin-
gle-mode fiber. The input power to the Rx must be less than +4.5 dBm. The
units will work back-to-back with the Model 2806 transmitter.
5) Connect the RF source (VCR, camcorder, cable television, etc.) to the RF
input on the transmitter.
6) Connect the RF output on the receiver to the monitor input. The monitor
input should present a 75 Ohm impedance.
7) Connect the AC power cord to the transmitter and the PS095 wall-mount
power supply to the receiver.
8) The unit is now fully operational. Verify the proper operation of the link by fol-
lowing the steps in Section 3.4, page 12. No user adjustment or attention is
required. See Section 3.5, page 13 for instructions on maintaining and clean-
ing the link. See Section 3.6, page 14 for information on troubleshooting.
3.3
Measuring RF Input Levels at the Transmitter
Excessive RF input to a fiber optic CATV transmitter
WILL
destroy the laser even if
the unit is not powered. Lasers can be destroyed by being overdriven for as little
as one nanosecond (10
-9
seconds). Because they can be destroyed so quickly, it is
essentially impossible to design a circuit or “fuse” that will blow before the laser is
destroyed. Therefore it is imperative that the RF level be within acceptable limits
BEFORE
the cable is attached to the transmitter.
1) Using a spectrum analyzer, determine that the RF level input to the transmitter
is within safety bounds.
2) The “RF In” LED on the unit gives a positive indication of the RF level. If the
LED is yellow, the RF level is too low. Increase in 2 dB steps until the LED turns
green. If the LED is red, the RF input level is too high. Disconnect the RF input
immediately. Decrease RF levels by 6 dB and reconnect the RF input until the
LED turns yellow or green. If it turns yellow, increase RF levels by 2 dB steps
until the LED turns green.
Ideally, the RF level should be checked with an instrument such as a spectrum
analyzer to verify that the levels are appropriate. If instrumentation is not
available to actually measure the RF levels, Force recommends adding 40 dB
of attenuation at the transmitter input; 40 dB of attenuation will adequately
protect the unit from the highest RF levels that might be seen in a typical
CATV installation. Do not attach the RF cable at this time, just verify the RF
levels and/or add the appropriate attenuators at the transmitter input.
3.4
Performance Verification
No user maintenance is required. The Model 2809
CATV
Linx
®
LDS CATV Receiver
contains no user-serviceable parts and requires no routine service. Contact the
factory if the unit requires warranty repair work. Once the units have been
installed, verify that the picture quality is good. If the picture quality is not good,
there are several likely causes:
1) The optical fiber may have large backreflections. Use an OTDR to examine the
fiber run.
2) There may be non-APC optical connectors somewhere in the system. These
cause unacceptable levels of backreflection.
WARNING
OPTICAL LASER RADIATION IS PRESENT AT THE TRANSMITTER OPTICAL CONNEC-
TOR AND THE FIBER THAT ATTACHES TO THE RECEIVER OPTICAL CONNECTOR
WHEN THE UNIT IS ACTIVATED. AVOID DIRECT EYE EXPOSURE TO THE BEAM.
