I am planning on putting up a ground mounted vertical for 40 and 80 meters.
Somewhere between 70-90 ft tall
and insulated from the ground. The antenna will be about 275 ft from the
shack. My question: is it advisable to feed a vertical with open wire
feeder? I am thinking it would work ok either directly or through a balun
on one or each end of the feedline, but how does one keep the RF from the
radiator from unbalancing the line? Or would it just tend to hit both sides
of the line and not upset the balance?

Doug, N4IJ