This is for Mobile use, as in running down the road, running power. My little 2011 Subaru Forester, I have the IC-7000 radio body mounted in the back, left side "cubical", right next to the door. The radio is grounded with #10, there's not a lot of metal within reach of it. The radio "head" is in the front of the car. Aux on the car radio's system is via a long shielded audio cable to the center console. I have #6 parallel cables running from the battery back to the radio, with snap on chokes at both ends. Also on the radio end of the #6, I have 2 caps, 50wvdc x 50,000mfd, and a tee where I've connected a 500w HF linear amp - works nicely, no problems, with all of this setup, no noise. The HF antenna is thru the roof, about midway past the the sun-roof and the back of the tailgate, it also passes through the roof rack for extra support (the hole has a big rubber grommet), and a short wire from the antenna to ground thru a small coil for better matching. This has worked well. OK, that's the basic setup. Here's the question: A couple of times, I've thrown some big batteries into the mix, using them to provide supplemental power to the amp, connected inline to the #10 cable... the radio is isolated to the main car battery, via a diode bridge and battery booster (then to the radio). Is there any advantage to grounding the batteries to the car frame, -and- grounding the solid state linear amp? The grounding "path" is a bit interesting, I wonder if I'm limiting output of the Amp, or input power. I plan on duplicating this with a truck, but with a larger Amp for 80 & 160m use. All replies are appreciated, at least they give me something to ponder.