[Boatanchors] vintage mobile radio and antenna

[WA5CAB at cs.com]

Converting from positive to negative ground at the same voltage is simple 
in a vehicle with no electronics in it, like a 1949 Ford pickup.  The only 
actual expense would be a new battery if the existing battery and ground 
cables won't reach to the opposite posts.

Besides reversing the battery, you reverse the leads to the fuel gage (if 
electric), temperature gauge (if electric), ammeter and the ignition coil.  
And the voltmeter in the unlikely case the vehicle has one.  Then, before 
starting the engine, you re-polarize the generator by momentarily jumpering the 
cutout relay several times with something like a piece of #12 insulated 
solid copper out of a piece of Romex.  The insulation is mainly to keep from 
burning your thumb and fingers.  I never did a Ford but I've done a lot of 
older Land Rovers.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 04/15/2013 15:36:41 PM Central Daylight Time, 
wrcromwell at gmail.com writes: 
> On Sat, 2013-04-13 at 17:09 -0400, Al Klase wrote:
> >On 4/13/2013 4:42 PM, Bill Cromwell wrote:
> >>.....You could use something like (exactly like) a bridge rectifier so 
> >>that your radio (or converter) doesn't care about the polarity in your 
> >>truck.
> >However, if the negative input to the radio is to chassis ground you'll 
> >have a problem unless you float everything for DC.
> >
> >Keep in mind that if you use standard silicon diodes, you're going to 
> >loose about 1.2 volts in the diodes, one on each side of the bridge, a 
> >pretty big hit in a 6-volt system.  Schottky diodes would be better by a 
> >factor of about two.
> >
> >Al
> 
> 
> Well...
> 
> jabut...
> 
> we're already talking about putting mobile tube radios in vehicle with
> positive ground AND only 6 bold (evil grin). So what's a diode drop or
> two?
> 
> 73,
> 
> Bill  KU8H
>