Thank you Al Patrick for your nice reply:

Be sure you hood and trunk are grounded well to the main body of the
auto. This is usually done with a short piece of flexible copper web,
well secured at each end.
I have already checked it. It is grounded quite firm with a very thick
cable.

You should be able to tell the difference in ignition noise and
alternator noise, the alternator noise is more of a whine but with
varying pitch as the engine revs up. If it is ignition, you can get
resistor plugs which are supposed to help. There is also supposed to be
a resistor that can be installed for the alternator whine.
noise is coming from ignition and there is another continious noise i
couldn't find the origin. There is somthing the technicians call
"brain" here in Istanbul, I don't know what is it called in English.
It seems that the noise is coming from that part. by the way,
alternator already has a resistor.

It is often VERY difficult to solve. I've heard of people purchasing a
car based on how quite the radio is on MW / AM. You'd be surprised the
differences in this on new cars of the same make, model, etc.
I learned it iss very difficult by my own experience. I tried VW polo
and golf cars and produced in 2000 and 1999, some has enormous noise,
some has a little and some has no noise at all. All with their
original blaupunkt radios. Impossible to believe. And I know by heart,
I will test it's radio's MW and LW band reception obsessively before I
buy a new car, If I will.
Regards, oan