i drive a volvo tractor ,i have 2 wilson truckers 2000 mounted on home made brackets,because the mounts on the truck mirrors are plastic.i have made a foot long perch type affair to mount antennas on.works great.now i tuned antennas seperately using a 18 ft. jumper first to set swr.drivers side down to 1.5 pass side down to 1.2 using a rg 59 au cable.for fine tuning later i took a 9 ft jumper to reset swr and got both down to 1.2.now when i hook up my co-phase harness swr goes to 3.1.now i cut the whips to get where i am now.hopefully i dont have to order a new set of whips.any thoughts on this.i have everthing grounded to hell and back.tks.mike