Re: Strange car radio symptoms

On Tue, 12 Feb 2008 08:20:49 GMT, rburt07@[EMAIL PROTECTED]
 wrote:

>There is a thing in the radio industry called a antenna null. That's when
>you located between the original signal and a very strong reflected
signal.
>It can knock out one or both channels and most times messes up the main
>radio signal. I would try other locations it the city our out on the
highway
>for a true test.  As you know it's always best to use a strong FM
station.

What you discribe is called multi-path.  That's where the signal takes
two or more paths to the antenna and results in out-of-phase signals
arriving at the antenna that cancel each other.
>
>I had a '94 Corolla that lost it's FM. I was worried as I wanted to sell
the
>car with everything working. The FM was so weak it has to be the antenna.
>Not easy at all but I replaced it the FM was some better but not like it
was
>months earlier.  I also noticed the lamp in the radio occasionally would
go
>dim then brighten again. I got to checking voltages to the radio. I
decided
>to rotate the fuse with another of the same value. Say, how about that,
the
>FM nearly blew me out of the car.  I saw the owner a few years later and
ask
>about the car and the radio.  It's nearing 200,000 and said it all works
>just fine. 

An easy way to test the antenna is to switch the radio to AM.  If AM
works well, the problem isn't the antenna.  FM will work with antenna
problems (shorts or opens) that kill AM.

Jack
N8BSR