am radio reception:

I have a 2004 Prius and the AM radio reception during my commuter varies from staticy to unlistenable. I first thought it might be radio conditions (cell towers, wifi etc.) but after talking to some people now believe it may be the car antenna or connection. Has anyone had similar problems? EC

Reply to
EC
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Yes. If AM reception is always lousy, as opposed to being lousy just in certain areas, the antenna is the first thing to look at. FM reception will often be fine even with a failing antenna. The way to test it is to plug in a new antenna (into the back of the radio), and hold the metal base of the antenna against a metal part of the car's frame, or better yet, a bolt that goes through the frame, since the bolt probably won't be painted.

If your car's antenna is a relatively expensive one and you don't want to spend the money until you're sure it's the problem, buy a cheap antenna at Radio Shack. The best thing for testing is the simplest: A one piece rod antenna. Nothing fancy.

Reply to
JoeSpareBedroom

There are a lot of things that can effect AM radio reception that won't bother FM reception. If the noise is a buzz and changes pitch with engine speed, then your problem might be ignition noise. If it is a whine and changes pitch with engine speed, then it might be a bad diode in your alternator. If the noise is a crackle but only happens while the car is in motion, it might be a loose antenna connection either at the antenna jack on the radio or the socket that the antenna itself screws into.

Ignition noise can be caused by bad spark plugs or bad plug wires. Use trial and error to find the cause. Start with plugs if you have a lot of miles on the old ones.

Alternator whine could be caused by the alternator or a bad battery. If the car always starts fine and never has a dead battery then it's probably the alternator. You can lose one diode in an alternator and still be able to keep the battery charged.

Then we get into exotic problems like wheel bearings or static buildup on the tires or the body of the car.

Cell towers and WiFi won't have any effect on AM radio reception. They operate at around 2,000 MHz and AM radio is around 1 MHz.

Jack

Reply to
Retired VIP

This car has one of those roof mounted short plastic antennas. In order to mount a 'regular' antenna, he'll have to get out the Greenlees and punch a hole in sheetmetal!!! (Not something *I'D* want to do to a Prius!!!)

Reply to
Hachiroku

He doesn't need to mount the test antenna to use it as a test instrument. That's why I said to buy a cheap one - it's not the one he'll end up installing. All car stereo stores keep a very basic one-piece rod antenna hanging in the shop for testing purposes.

Reply to
JoeSpareBedroom

The big problem however is getting at the antenna connector at the back of the radio. These radios are buried. It could also be a broken shield, which would cause more static. It could be the radio itself. If the radio is easy to remove, I'd remove it, and bench test it myself, otherwise you would be better off taking it to the dealer and pay the man.

Reply to
dbu'

I have had cell towers and power lines affect my AM reception as I drive under/near them.

Reply to
badgolferman

You may have been hearing a dirty T1 line. Direct interference from cell sites to a AM band radio is very remote. Mixing down would not be possible either.

Reply to
dbu'

The Prius doesn't have either spark plug wires or an alternator, It has coil on plug igniters with integrated switching transistors (the computer just sends them a logic pulse) and a 100 amp DC-DC converter keeps the 12v battery charged off of the HV battery while the car is in READY mode (the equivalent of started and running for a normal car). The AM band noise is a known problem as it has been discussed on the Toyota-Prius yahoo group and the fix it to reseat the connection to the radio and remove the antenna and clean off the paint where the nut makes contact with the body then apply dielectric gel or petroleum jelly to prevent rust.

Reply to
Daniel Who Wants to Know

Grounding comes into play much more for AM than it does for FM. My last two Toyotas had the same recall: a screw coming loose on the antenna caused the AM reception to fade out.

The fix? Place a star washer between the screw and the antenna mount. Took care of that one all by myself! ;)

If he does use an 'external' antenna as you suggest, he'll have to make sure he grounds it to the chassis sufficiently to see if it makes a difference. I would attach a wire to a lug big enough to go around the base of the antenna, and then connect an 'eye' lug to the other end and ground it to the frame in a good location, perhaps even to the - side of the battery itself.

Reply to
Hachiroku

You might have been picking up trash from the power lines feeding the sites but the cell transmitters themselves won't cause you any problem. All of the cell equipment runs on 48 vdc and the power supplies are chopper types that create a lot of RF noise. They are filtered extremely well so the noise shouldn't get outside of the cabinet much less to your AM radio. That is if everything is working right.

Jack

Reply to
Retired VIP

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