[GroundUrMast]

Back in the days when the majority of TV was broadcast in the VHF bands, RG-59 was adequate. It's not too lossy at lower frequencies.

RG-59 is an unusual type of coax to find in a satellite system. It lacks the shielding that should be used in that application. RG-59 will have roughly 1.5 dB more loss than RG-6 for each 100' when used for UHF. The difference just gets worse when you get into the 1 to 3 Gigahertz microwave range.

Another problem with RG-59 is the connectors used are usually the old crimp style. These are often installed using the wrong tool so they are either loose or overly tight. Smashed, crushed or kinked cable results in a change of the cable's operating impedance and results in some signal being reflected back and forth in the cable. Of course, a loose connection causes trouble as well.

I would not suggest that you replace working coax. But if you have doubts about a particular run of cable, it's not worth fighting with. An amplifier should never be installed as a repair when there is real trouble still present elsewhere in the system. Before you go to a lot of work installing a new run of cable, 'ground lay' it... Run in on the floor, through a window or vent, etc. -- Just to verify that it really does improve the system performance. (If you prove the existing run of coax to be good, you may be left with one of the least expensive, but vital test tools, a known good cable.)