coax booster

[archp2008]

I have two hdpvr Motorola units from Rogers. I am using one upstairs and one downstairs using a splitter and approximately 75 feet of RG9 coaxial cable. I can use one at a time w/o the splitter and get perfect reception on all channels, but when I use the splitter to connect both of them at the same time I lose three or four of the highest numbered HD channels on both boxes. I know that Rogers could fix if for $ but I'm hoping to aovid the monthly fee for the seldom-used second box. It is a good quality splitter. How important would the quality of the short cable lengths attached to the splitter be? Would a coax booster help. Would the boosters used for satellite dishes work for HD cable tv? I seldom would use both at the same time.