am radio reception


  #1  
Old 12-15-00, 10:04 PM
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I am a mailman and my vehicle has no radio-therefore I
have built a portable stereo boom box of sorts-just
a wooden box with a stereo cassette player with speakers and a small antenna unit installed.
everything is great except the am gets really bad reception.
the vehicle is mostly a aluminum box-when I turn the engine on and Im in am mode I get static caused by the engine and
it get worse when applying gas while driving.
I did find a way to put the attenna outside the vehicle and it did improve reception but the static problem from the engine remained-to a slightly lessor degree.
Anyone have a solution to this problem?
 
  #2  
Old 12-16-00, 08:13 AM
Smokey
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Good Morning, beary:

It's been a long time since anyone came in with a problem over AM radio. AM (Amplitude Modulation) is highly prone to picking up static and electrical interferance.

In the case of your situation, the radio is most likely picking up ignition noise from the engine's spark system.
Wires to the sparkplugs have a tendency to radiate noise.
One of the fixes is to replace the wires to the spark plugs with "radio resistant" wires. They use a nylon core that is impregnanted with carbon.

Since it is not your vehicle and you don't want to put any money into it, there is a fix that works now and then. Remove one end of the coil wire (if available)and tie a simple overhand knot in it. This cancels the electrical field surround the wire and is effective more often than not. Another fix is to take an automotive ignition condenser and put it on the output of the alternator (+12 volts) and, of course, secure it to a good ground.

If you want to spend a few dollars on the fix, Radio Shack sells "Interferrance Kits" in their auto radio section. These calm down the noise on the +12 volts.

The other (and last) fix is to switch to FM.

Smokey
 
 

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