For all the complaining about previous owners messing things up, I see that
some folks are still recommending installing radios backwards by trying to
isolate them from the car chassis. DON'T DO IT!
First is the simple idea that it is stupid to do something you know is
wrong. Even if you are willing to risk the potential short circuit, it won't
work right. There is a reason for grounding the antenna.
First the cars body acts as a counterpoise, which is necessary to good
reception. In the good old days you had to have an actual connection to a
ground. Things have improved, but not that much. You still need a second
element besides the mast. My transmitter is grounded through an eight foot
spike driven into the ground. (A friend of mine claims he has trained his
dog to keep the earth around his ground rod moist to aid in conductivity).
Secondly, cars generate a lot of noise. The ground and shielded lead is one
way to keep the noise from coming in through the antenna lead. That doesn't
eliminate alternator whine, or other interference from coming into the radio
though the power leads, but that can be eliminated other ways.
The right method? There are adapters that allow radios to be hooked up in
reverse polarity situations. J.C. Whitney usually has them, but they go in
and out of the catalog. They aren't in there now. I'm sure there are other
sources, perhaps a look at Hemmings will help.
Respect your car. Do it right!
Jack, KA9HEL
Bell Labs
(I was going to add my PH.D., but it was someone who signed his messages
with a Ph.D. that recommended the idea of isolating the radio. Having one is
no gauge of universal knowledge, or any knowledge at all).
J.
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