Ok this one has stumped me for a while. Looking for info for a question in another thread I found a Voltage drop reducer that will handle the amp load but here is the real question. What are the issues with running a six volt positive ground radio = stock 51 Mercury radio, on 6 volt negative ground because I need to use a voltage reducer? I had been thinking of just running a small 6 volt battery tucked away somewhere and charging it and go again and have it pos ground and the battery work totally separate from the rest of the rig. That radio isn't going to be the main source of sound in the rig but I want it to work for show and tell time .
If you are going to use a 6 volt positive earth radio on a 6 volt negative ground system you would have to make sure that the radio is totally insulated from the body work. Then you can run a lead from the radio casing to the positive terminal on the battery and a lead from the negative terminal on the battery to the radio feed. with an inline fuse. I believe there are place around that with convert you radio from positive to negative earth.
some radios care, some don't. Looking at the schematic might help figure it out. Or listen to old guys who've run them with reverse polarity and had it work... they generally use a ******** to make the high voltage for the anode, and it's crude AC, rectified with a rectifier tube. So it should be fine? although there might be some electrolytic capacitors in the low voltage side, that might not like being wired up backwards. post the schematic, we'll take a look.
Mount the radio on a lump of timber or plastic and do as Brading suggests. Radio's do care about the polarity, except when you are trying to let the smoke out.
My suggestion would be to Buy a Lithium Jump start battery a nice fat one. Put it in your glove box with a line going to the car battery via a power port you hide in the glove box. Then run power from the Jump start battery to a voltage reducer and then to your radio connected as it was designed. You might have to push a ****on on the jump battery to get juice to come out. But it can charge right off your 12V vehicle and power the radio on 6V positive ground. And the best part is you can test all this on the bench without it being in the vehicle.
I didn't think jump start battery and voltage reducer but that is worth studying. The radio is in a 51 Mercury dash But looking at photos of another 51 Merc radio it looks like a few insulating washers will get that job done with maybe some other insulation in a spot or two. There aren't that may spots to insulate and some tape can take care of the rest. ATTACH=full]6573719[/ATTACH]
Don't forget that the shield part of the antenna lead is connected to the case of the radio. Check that there is no continuity between the shield of the plug, and the mounting of the antenna (usually a big nut with a star washer on it, that mounts up under the fender. Otherwise if you are connecting the radio up with reverse polarity, and an insulated case, you'll blow a fuse.
I know that this is not what you are asking. All operations by a remote with the period face left up. Turn the volume knob and the drop down face reveals all . Blue tooth and usb . Just takes any risk of short out of the equation.
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