How many tv's are/will be connected?? Also please make a new radar plot with the antenna at 25 foot antenna height. Your Grandparents will receive some of the Canada digital tv stations with the antenna at the current default height of 10 feet and with the antenna at 25 feet high will receive more Canada digital tv stations and might receive some American digital tv stations. Here are some converter boxes to use ,
http://forum.tvfool.com/showthread.php?t=380 Leave the current 10 foot radar plot in place and make a new 25 foot radar plot.