There are several factors at play here. "Static" and a "whine that changes pitch" are two different problems with different causes.
Static is usually caused by a poor signal, a bad ground, a damaged antenna or antenna lead, an improperly connected antenna plug, or an improperly matched antenna and radio (requires specific internal tuning to align).
Poor ignition or non-suppressed ignition wires or non resistor spark plugs produce a clicking sound through the radio that fluctuates with engine rpm. It too is quite annoying. A vehicle driving in this condition will generally create a signal that other vehicle radios can pick up as the two near or pass each other. It is not static in the radio sense, it is a stray radio signal that is broadcast across the frequency spectrum and picked up by your radio. Correcting these deficiencies usually corrects the problem.
A whine that fluctuates and changes pitch, is generally created by an alternator as a result of it generating an AC voltage that is converted by diodes in to a DC voltage for use in the vehicle. Current naturally flows from this as voltage and current are best friends.
A whine of this type comes from within the 12 volt power source wire and can indicate alternator trouble, can be naturally present within that particular type of alternator, and can usually be filtered out.
The condensers referred to in previous submissions do help in cleaning up noise signals or interference.
The only way to eliminate a whine signal that is in the power source is through the use of what have been commonly referred to as an "RF Choke", or a "Noise filter".
These normally consist of a combination of a type of condenser and an "rf choke". These were sold by the millions through Radio Shack and other parts supply houses for years, to assist with audio systems, amplifiers and two-way radio power supply clarity.
I did a quick google search and found that there are versions of them at many on-line suppliers.
Just be sure to get one that will handle the amount of current that your radio pulls. You do not want to overload one of these, or any other electronic device.
Although they should have instructions, most have a positive lead which gets spliced in to the radio's power line, a negative (that should be obvious to you), and another line that be comes the new positive feed for your radio/amplifier etc,.
Having said that, there are versions that splice in to the positive feed and do not have the other connections noted above. These have the impact of lengthening your positive lead with no other connections.
I hope these basic points help.
Good luck!
