Teleste AC1500, User Manual, Page: 8 / 16

User manual AC1500
59300547 Rev.001
21.4.2016 8(16)
passive return path module. Options for the return path module (Figure 4
pos. 20) are AC6250 (65 MHz), AC6251 (85 MHz) and AC6252 (204 MHz).
Setup
Preparation
Check installed plug-in modules in the amplifier. Note! Amplifier does not work if
one of these components is missing.
− Install input and output diplex filters as called for by design.
− Install input attenuator and input equalizer as called for by design.
− Select appropriate interstage pivot point according system’s highest
frequency.
− Install ALSC, MLSC or transponder unit. Assuming AC6158 or AC6188 is
in use adjust the gain and slope controls to mid-position (Gain: 0 dB,
Slope: 0 dB).
− Select appropriate plug-in module into forward path universal plug-in slot
to set the operative gain according to amplifier usage (Trunk/distribution).
− Return path universal plug-in slot must be equipped at least with the 0 dB
JDA series attenuator.
− Check the presence of return path gain mode selector. Start with “low
gain”, use “high gain” mode only if needed.
− Install return path module with designed frequency range.
Forward path
Verify adequate signal at the input of the amplifier (Figure 4. pos. 3) Note! If the
income level of the amplifier is quite high or unknown, replace the input
attenuator with an attenuator of rather big attenuation value e.g. JDA915 (15
dB).
Set the output slope of the amplifier according to the network plan calculation by
means of input equaliser (Figure 4 pos. 6). The signal can be measured at the
-20 dB output test point (Figure 4 pos. 11). To reach the desired output level
select an appropriate input attenuator for the plug-in position 5 (Figure 4). Both
attenuation and slope control is achieved by plug-ins of the JDA series type
ranging from 0 dB to 20 dB in 1 dB steps. Output level and slope can be fine-
tuned with AC6158/AC6188.
Assuming that AC6158 ALSC module is in use, switch it to “ALSC On” mode.
ALSC (Automatic Level and Slope Control) keeps the output signal level stable
irrespective of input signal level variations by adjusting the interstage gain and
slope controls based on the pilots. Gain and slope are adjusted slowly in small
steps to guarantee stable operation in long amplifier cascades.
If new output levels need to be set, ALSC should be first disabled, then gain
and slope adjusted (with manual controls or plug-in modules) to achieve desired
pilot levels, and then ALSC enabled again.
Return path
The return path adjustment is based on unity gain principle such that the return
path gain of the amplifier station exactly matches the loss of the cable following
it (i.e. the cable span toward the headend).