Cisco Cisco 1 GHz GainMaker Amplifier Guia Da Instalação
4015992 Rev D
5
Setup Procedure
6 Install the design value AGC pad. Refer to QAM AGC Pad Selection in this
document for pad selection procedures.
7 Follow your system's standard balancing procedure for adjusting the amplifier
for design RF output levels, using either Thermal set-up procedures or Manual
set-up procedures.
8 Record the balanced amplifier's RF output levels.
9 Move Switch 1 (S1) to position 3 - AGC Operational Mode.
10 Slowly adjust the AGC Gain pot to match the RF output levels recorded in step 8.
9 Move Switch 1 (S1) to position 3 - AGC Operational Mode.
10 Slowly adjust the AGC Gain pot to match the RF output levels recorded in step 8.
Once this is done the AGC setup is complete.
Note: When adjusting, allow a little time for the AGC to settle as there is some
delay between pot adjustment and the associated RF level change.
11 If the RF output levels in position 3 - AGC Operational Mode cannot be made to
match the levels recorded in step 8 by adjusting the AGC Gain pot, the AGC pad
value may need to be changed. In that case, go to step 12. Note that this should
only be necessary if the actual amplifier output level of the QAM pilot carrier
deviates by more than 2 dB to 3 dB from its design output level, which is possible
due to frequency response characteristics of the plant.
12 With Switch 1 (S1) in either position 1 or 2 (the position you used for initial
balancing) and the amplifier output levels adjusted properly, measure (see note
below), and record the output level of the QAM pilot carrier at the main output
port. Subtract the appropriate AGC reference level from the measured level to
determine the AGC pad value required. Refer to QAM AGC Pad Selection in
this document for AGC reference levels and pad selection formulas.
Note: When measuring the QAM pilot carrier output level, be sure the meter
used is capable of measuring QAM carrier levels accurately. Some earlier meters
were only designed to accurately measure CW or NTSC modulated carriers, and
may provide erroneous readings when tuned to a QAM carrier.
13 Change the AGC pad value based upon the calculation in step 12.
14 Repeat step 9.
15 Repeat step 10.
16 After ensuring that the RF output levels in position 3 - AGC Operational Mode
14 Repeat step 9.
15 Repeat step 10.
16 After ensuring that the RF output levels in position 3 - AGC Operational Mode
are the same as those in the position used for initial balancing (position 1 or 2),
the AGC setup is complete.