QST March 1979 has the data on ZIP cord as a feedline. In short the losses are on the order of 4db/100ft at 14Mhz and 8db/100ft at 28MHz. If you are an ARRL member you can still download a copy of the article at; http://www.arrl.org/members-only/tis/info/pdf/7903031.pdf Dave NR1DX