i have had good luck with 3/4 grey conduit and feeding it up a tree 10' at a time. I have a ladder line up 30', could probably get 40, but heavier antenna will bend the conduit as shown in the picture. Easier to remove too. I have a similar setup with my HF antenna using 2" conduit. More of a struggle, but got the 27' antenna 30' up and other than the conduit at the base, almost invisible from the street.