Operating instructions

Overview 2-11
Return Path
The circuit board of the MBV3-100* amplifier includes the return path. This equips the
MBV3-100* to pass signals in the return or upstream direction. The standard circuit board
contains all components including the diplex filters, with extended return bandwidth, for the
amplifier input and output.
Optional SRE-*-* return equalizers compensate for cable attenuation and are available in 1 dB
increments for S-split, and 2 dB increments for all other splits, from 0 dB through 12 dB.
There are JXP-*B pad facilities located at the input and output of the return path. You can use
these pad facilities as test points or signal injection points. The return output pad value is
normally selected to control the return signal level into the next upstream amplifier. Select an
appropriate return input pad to attenuate excessive input signal.
The return-input test points and the return-output test point are −20 dB directional couplers.
These test points present 75-ohm source impedance and do not require special test probes.
Ingress Control Switch
The ingress control switches (Optional ICS, illustrated in Figure 2-11) provide return-path
signal attenuation or cutoff in the MBV3-100*. Switching is accomplished through the frequency
agile LIFELINE status-monitoring module, which you can purchase directly from AM
Networks.
The ICS provides a means of isolating sources of ingress from a centralized location. Using a
downstream command through the LIFELINE status-monitoring system, you can attenuate the
return path through the amplifier by 6 dB or by 38 dB. By reducing the ingress level at the
headend or monitoring point, you can further isolate the ingress source.
After you isolate an ingress source to the last possible amplifier, node, or line extender, you can
shut the return path off at that location. This limits the impact of the ingress on the remainder
of the network while eliminating the source of ingress.
MBV3-100* Installation and Operation Manual