John:

Before I answer the questions you asked (I notice most correspondents
answered a lot of questions you didn't ask), I want to point out a few
things. Ever think about how many tires wear out every year? You know,
1/2" or more of rubber worn off millions of tires? Cubic yards of rubber?
Where does it all go? Piles of ground rubber along the roads? Well, some
of it remains stuck to the surface of the roadway. Look at any cement
roadway for confirmation. New, nice white or light gray. Old, dark gray to
black. Now, in spite of EPA, go out and press the leads of an ohmmeter to
the tread of your tires. Not the sidewalls, which may be a different mix,
and usually don't contribute anyway, but to the tread itself. Slightly
conductive, unless they are an unusual brand. So, as you and all the other
vehicles travel on that fresh, non conductive asphalt, day by day you make
it more and more conductive. So the current which creates the noise, and is
driven by voltage from triboelectric and other effects, is markedly
different when traveling on a conductive surface than it is on a
non-conductive surface.

So, in the order you asked:
No, you didn't imagine it.
You have noise on old asphalt because it tends to be not a good insulator,
and current flows, creating noise.
Fresh asphalt is much less conductive, so less noise generating current
flows.

--
Crazy George
Remove N O and S P A M imbedded in return address


"John Smith" wrote in message
...
Here's one to explain:

There I was, driving along a two-lane asphalt highway trying to listen to
an
AM band station on 1230 kHz about 70 miles away (they only run 250 Watts)
and getting considerable static. I noticed that the static diminished when
I
came to a stop and resumed when I began again. This was not alternator
whine
or spark plug noise--more like white noise. So, I thought, it must be
static
from wind in the antenna or maybe tire-on-roadway static.

Then I hit a section of road with a new 3-week-old layer of asphalt laid
over the old asphalt. The noise disappeared! The noise returned when I
drove
off that new section of asphalt. Hmmmm. Did I just imagine it? So, I asked
my XYL to pay attention to the station/static when the next opportunity
arrived. Another section of fresh asphalt produced the same thing and she
can verify it. It happened every time.

Now I ask you... why would I have statickey noise from driving on old
asphalt? Or, maybe the question should be why would fresh asphalt be a
noise
quencher? Or something.


Thanks,
John
KD5YI