> However, don't most CB radios use the metal case as a common
> ground?
Yes, and if not the case, then almost always the base of the antenna. With
care, you can run it isolated (like your block of wood), but the performance
won't be as good. Had friend almost burn up his MGA this way once, he
didn't realize the antenna mount was connected internally (no fuse !) to the
negative power lead. He mounted the antenna to the rear bumper, which
apparently wasn't grounded to the body because of rust. About 300 miles
later (on our way to Florida for summer vacation), the rust broke through
and the antenna lead started smoking ...
> Then if you mount the metal bracket to a metal car, you
> have just created a short circuit... Or am I missing something?
The converter completely solves the ground issue. In effect, it creates a
+12v supply relative to your car's ground, even though your battery is
a -12v supply relative to ground. The radio and antenna can be grounded to
the car without fear of shorts.
> I once (in my young stupid days) mounted an under dash, negative
> ground, 8-track in my Positive ground Triumph. I solved the polarity
> problem by mounting the 8-track to a piece of wood, and attaching
> the wood under the dash... Like I said, stupid... But I didn't have
> a Positive ground radio....
After learning how easy it is to convert a Triumph to negative ground, I
wouldn't do it any other way. Although it's best to switch the connections
to the ammeter and ignition coil, it will actually work if you just switch
the connections to the battery ! Polarize the generator (which can be done
by simply mashing the cutout contacts closed with your thumb) and off you
go.
Randall
59 TR3A daily driver - negative ground for many years
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