I do not think Winnebago installed a signal amplifier. My manual also shows that there may be an amplifier but the manuals are sometimes covering multiple models and options. I looked for an in-line amplifier in our coach as well and it seems not to exist.
Martin & Michelle and our dog Blue, Paradise, CA.
2016 Winnebago Vista LX 27N, Sumo Springs, rear track bar, Safe-T- Steer, Dish
2017 Equinox Premier AWD V6, Blue OX base and bar, SMI Stay and Play Duo