the computers should be shielded

80 watts is a substantial amount of power. Most mobile rigs are in the 25 to 50 watt range with most of the dual band units limited to 35 watts. At 80 watts the current draw will be 17 to 20 amps. This dictates direct connection of both the positive and negative power supply lines to the cars battery. Both should be fused and be at least #12 gauge stranded #10 preferred. You can buy premade cables just for this purpose. The radio chassis should be grounded to the vehicle’s chassis via some substantial braid. If you don’t and you lose your ground connection your coax to the antenna will turn into a toaster element. Under no circumstances use a cigarette lighter adapter to supply power to a radio that big.

The antenna should also be grounded. I would shy away from mag mounts. The coax is usually thin and becomes a radiator above 50 watts. The best is select a spot in the center of the roof and with a hole saw drill a ¾” hole. Use a limiter on the hole saw to avoid drilling through the head liner. I use a piece of scrap 1” PVC cut to allow 1/8” of saw to protrude. Do some research and visual inspection so you don’t drill though a wiring harness or worst case an airbag. Most of the time the center of the roof is clear to drill. You also want to be clear of any cross members used to reinforce the roof. Then use an NMO mount kit with RG8X unterminated. Once you snake the wire to the radio cut the cable to length and install a PL259 at the end. Don’t coil excess coax under carpeting, inside the roof or pillars. Cut just enough to reach the radio with a decent amount as a service loop. Use a decent antenna like a Larson, Diamond or Comet.

Cars have built-in shielding for RF sources outside the car. There are lot lower susceptibility thresholds inside the car so you can’t afford to cut corners. You would probably want to check the SWR at low power before you go key down at 80 watts. There are a couple of inexpensive watt meters that can do this. There isn’t a lot of guidance from the asians including Toyota when it comes to 2 way radios in their cars. GM , Ford and Chrysler have published comprehensive guidelines. Here is a URL I like to use. There is plenty of information on the web regarding mobile two way radios.

http://www.repeater-builder.com/tech-info/gm-mobile-radio-install-guide.html

So after all this  your tailgate opens when you transmit it means you screwed up and you better go back and check every single connection and make sure you did not drive a screw through the coax.

So Scotti who do you like better: Maryann or Ginger on Gilligan’s island? {black}:sweaty: