Olson Technology OTPN-800CH - Manual (Page 6)

Figure 2 - Typical CNR vs. Optical Input Level
INTERNAL TEST POINTS and ADJUSTMENTS
The OTPN-800CH receiver has an internal adjustable pad to allow the RF output level
of the node to be adjusted. There is also a plug-in equalizer to compensate for cable
slope. These adjustments are accessed by removing the 8 thumbscrews that hold the
top cover on. The unit should not be operated for extended periods with the top cover
removed. This is because of RF ingress and contamination from dirt or other objects.
When replacing the top cover, be sure to firmly tighten all thumbscrews. RF ingress or
oscillation can be caused by loose screws.
Figure 3 shows the locations of the internal adjustments. There are two forward RF out
adjustments, a variable attenuator, and a 10 dB switchable pad. This gives the unit 20
dB of RF output range. If the optical input is between -3dBm and +2dBm, then the 10dB
switchable pad should be as shown above with the flat part being parallel to the front of
the unit by rotating the jumper if needed. The variable attenuator can then be used to get
the RF output to the correct level. If the optical input is in between -8dBm and -3dBm,
then position the 10dB switchable pad should be rotated so that it is perpendicular to the
front of the unit.And then adjust the variable attenuator for proper RF output.