Posted: 11/16/2004 5:57:00 AM EDT
| I'm just far enough from Tampa that my AM reception is hit or miss and I have trouble getting talk radio. Is there a way to improve the reception? Some of the interference seems engine related. |
Hint: "I CAN'T DRIVE ---------------------- FIFTY-FIIIIIIVVVEEE!!!" ETA - Hey Cap. make one of these... Free Plane Antenna |
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Receiving distant AM stations in an automobile is difficult, because electrical noise from the engine's ignition and electrical systems drowns out weak signals. Interference from the ignition system usually makes a popping sound that speeds up with increasing engine speed. Using non-resistor-type spark plugs or aftermarket (non-suppression) spark plug wires are common culprits. Interference from the electrical system usually sounds like a smooth whine that changes pitch with engine speed (caused by the alternator), or a steady hash that appears when you turn on the A/C, Heater or Vent blower (caused by sparking brushes inside the blower motor). Aftermarket filters are available that can be connected at the alternator or blower motor to reduce this noise. Next, make sure that any original ground straps between the engine and vehicle frame are still intact and in good shape, as well as any spring-type straps between the engine hood and fenders or front cowl. Often, these items get removed during car repairs. A poor radio antenna connection also makes the signal weaker. Often, the outer conductor of the antenna cable (the braided wire) will develop a poor connection either where it plugs into the radio, or where the bottom of the antenna mast is connected to the vehicle's body. Check for tight connections at both ends, and replace the antenna and cable if it looks suspect. Also, relocating the antenna mast to the rear of the vehicle (further away from the engine) sometimes helps. Note that some AM radios are much better at handling weak signals than others (due to better noise-rejection circuitry and higher signal sensitivity). Unfortunately, the AM section in many car stereo systems is just an afterthought, with little attention paid to how well it actually works (since NOBODY listens to AM anymore, right?  ). Also, nobody bothers to test or rate the AM performance of car radios, so finding a good model is mostly a matter of luck.
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