Gery, I use 450 ohm open line here and what I did is.  I cut pieces of about 
one and a half plastic pipe which I run through my tower and lash down with 
wire  It sticks out about a foot from the tower and with a hole drilled 
through it I hook it to the feedline.  I use three of them to my dipole Up 
at around 45 feet.  Drill holes through the pipe where you tie it to the 
tower so it can't slide. The line runs through a slotted hole through the 
edge of the shack window to my balanced tuner.   73
Ed K7UC