Cable Equalizer; Example 1; Example 2 - Motorola STARLINE SERIES Installation And Operation Manual

3-2 Amplifier Setup
Secure the electronics chassis in the housing and torque to 18 to 22 in-lbs. to facilitate heat
transfer and avoid damage from overheating.
Perform a bench alignment. Pre-aligning the MB*/* response on the bench (Section 4,
" Bench Testing" ) for a system signature simplifies field alignment.
Field sweep the entire bandwidth of the amplifier to correct frequency response for passive
signature and roll-off.
Close the housing in accordance with the instructions in Section 5, " Installation."

Cable Equalizer

Select the appropriate model SFE-*-* to compensate for cable attenuation versus frequency and
to obtain the proper output tilt. The MB*/* is equipped with the MDR-*MB/*/II interstage
equalizer and flatness board, which compensates for cable attenuation. Any cable or passive
slope beyond that of the MDR-*MB/*/II must be compensated for by selecting and installing the
appropriate SFE-*-* cable equalizer.
Equalizers are available in 1 dB steps from 0 dB to 22 dB. The following examples describe how
to choose the correct equalizer.

Example 1

The amplifier location includes 20 dB of cable (at 870 MHz) between its input and the preceding
amplifier. Consider cable loss only. Exclude any flat loss due to splitters or other passive
devices. The internal equalizer, model MDR-8MB/12/II, compensates for approximately 16 dB of
cable. Subtract this cable length from the 20 dB of this example (20
the proper equalizer in this case. With this equalizer installed, the amplifier reproduces the
output tilt of the last upstream amplifier.
When selecting an equalizer, choose the next lower value if the exact value is not available or in
cases where the calculated value makes two choices possible.

Example 2

The MB*/* is used in a link following a fiber node. The fiber receiver output is flat and connects
to the input of the amplifier through 18 dB of cable plus passive loss. Determine which is the
proper equalizer to achieve the 11 dB output tilt from the MB*/*.
Calculate the equalizer value using the following equation:
SLOPE eq = TILT out + SIG lo – SIG hi – SLOPE ieq
where: SLOPE eq = required SFE-87-* slope
TILT out
SIG lo
SIG hi
SLOPE ieq = interstage equalizer slope (12 dB)
At an operating frequency of 870 MHz, 18 dB of cable produces approximately 3.9 dB of loss at
54 MHz. This suggests that the channel 2 signal input to the MB*/* is 14.1 dB greater
(18 3.9 = 14.1) than at 870 MHz. Our example assumes that the high-end frequency level into
the MB*/* is 12 dBmV.
MB*/* Installation and Operation Manual
= required amplifier output tilt
= signal input level at 54 MHz (channel 2)
= signal input level at 870 MHz
16 = 4). The SFE-87-4 is