I have the matching pair of TK-7180 and the 8180 mobiles. The VHF is 50 watts and the UHF is 30 watts. I had the antenna's roof mounted and I noticed a problem. When I key up on the VHF radio, what ever the UHF is receiving, the signal is cut way down, and in some parts of the county, it gets cut out completly until i unkey the VHF then its fine again. I had both coax cables run together, but then I ran the UHF on one side of the vehicle, and the VHF is run to the other side of the vehicle hope to solve the porblem, this helped a very little bit. The antenna's are 15 inches apart almost in the center of the roof in a straight line. The vehicle is a 1992 Ford explorer. Anyone know what could be wrong? Thanks Ed