Is there still any Dual line systems in the US? I know that comcast had a 550MHz A cable/450MHz B cable system in Dallas Texas but once TWC took over they removed the B line plant and upgraded the A cable to 1GHz with 860MHz actives staying in place so if there was an 860MHz node or amp it was not replaced same for the outlying 750MHz system they put in 1GHz modules in the amps that were 750MHz and left the 860MHz nodes and amps intact. I know that we have some magnavox mainstation housings that have at least 860MHz drop in upgrades and other parts have Antec, phillips, and CCOR amps with drop in upgrades to go along with the majority of motorola amps and nodes with about half of the nodes being 1GHz aurora networks nodes and some being 1GHz Harmonic nodes.
Before TWC took over comcast converted all of the QAM carriers to QAM256 from QAM64 and moved all of the digital QAMs in the dual line areas to the A cable.
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