Digital Equipment ChannelWorks DECTV-AA, Installer'S Manual

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Preparing The Cable TV Network 3-5
Figure 3-3 IF Gain And RF Output Controls
IF Gain Control
RF Output Control
3. Rotate the IF Gain control clockwise until the red overload indicator turns on.
Back off the control until the indicator light goes off. This optimizes the IF gain
setting of the TransMaster.
4. If the output level of the TransMaster needs to be increased, adjust the RF Output
level control clockwise until the desired level is obtained.
The downward adjustment range is 10 dB for the RF Output control. If additional
gain reduction is required, add external attenuators to the TransMaster’s RF Output
port.
5. Connect the TransMaster to the cable TV network.
In most cases, a cable will run from the return splitter to the TransMaster’s RF
Input and another cable will run from the TransMaster’s RF Output to the forward
combiner.
Once the TransMaster is on the cable TV network, you must observe the forward spec-
trum of the system on a spectrum analyzer. Compare the adjacent channels’ video car-
riers and a signal (set at the level you have been testing with) injected in your data
channel using the RF Combination Meter.
Set the gain (RF output level) of the TransMaster so that the RF Combination Meter’s
signal level is approximately 3 dB below (lower than) the video.
IF Overdrive LED