Audio Systems: Replacement Stereo. FM, good; AM, bad, stock radio, resistance test

Question
Kelly,

I replaced my stock radio in my 1998 Audi A4.  Things are working okay except that my AM reception is weak.  There is not all that much static-y noise- mostly a very weak signal.

The AM reception on the old radio was perfect so I do not think it is the in-glass antenna.  I bought the antenna converter.  Could this be faulty?  I also saw something about a booster for the antenna.  

Thanks,
Jon

Answer
Yes the adaptor can be faulty. It might even pass a basic resistance test with a multimeter, yet still give marginal performance. I would try another brand of adaptor, I think the VW/Audi are pretty common, and most shops should keep them in stock. They might even have a spare you could try in the parking lot. Remember, Am will work even with a plain old wire and no ground connection. FM works best with an antenna about 32 inches long, and the braid grounded. Make sure all your connections are tight, there may be connections under the panels you do not know about. Many cars have a cable from the trunk to the glovebox or kickpanel area, and then another from there to the radio.