Poor AM reception

You don't understand what I mean. Your antenna is divided into two circuits. One is the center lead of the antenna coax which terminates as the antenna mast. The other part is the shielding of the antenna coax which terminates as the base of the antenna. The base of the antenna must be grounded to the fender or another large portion of metal in the body. The antenna mast receives one half of the radio transmission signal, either AM or FM. The other half of the signal is received by the ground plain of the antenna, which is the fender or large metal part of the body. The properties of AM and FM differ. Most manufacturers only want one antenna on their vehicle, so the antenna was designed to optimize FM reception, because it has a better sound quality and is more popular. Therefore the antennas ability to recieve optimum AM band signals is compromised. This is why the average antenna mast is 31 inches long. If you short out the center antenna lead to the shielding you will still get some FM but no AM. Because the antenna is optimized for FM, any fault in it will affect AM band far worse than FM. As for aftermarket radios not being designed with AM reception in mind, that would only apply to low end equipment. Any quality brand name deck will be able to pull in AM band stations just as well as a factory radio, provided the correct antenna adaptors are used if any are required. Many manufacturers are using unique style antenna lead tips and if sub-standard adaptors are used, you again will compromise the antenna and AM will be affected more than FM. sparky

the12volt wrote: Rule of thumb is if you have FM reception and no or poor AM reception, replace the antenna. If you have AM reception and no FM reception, replace the tuner. My advice is try another antenna.

Why are you making this difficult for the poor guy. I have done a whole lot of poor AM problems and the above advice is right on the money. Try a new antenna (they are cheap) and see what happens. You can probabally return it if it doesn't end up curing the problem anyway.

I am not in the habit of just throwing parts at a problem. I figure out what the problem is and fix it correctly. If the antenna were replaced without knowing the importance of the connections and a good ground then he may never resolve the AM noise problem. sparky

This is why I love this site.  Everytime I come here I learn something new.  Thank you sparkie I never knew that about antennas.Cause I'm So white and nerdy...

First Class Certi-fried installer

You are very welcome. Even us old guys still learn something now and then.sparky

Gee guys...I didn't realize you cared so much for poor lil' ol' me. Seriously...thanks for the education. Now...more dumb questions to ponder: 1. Re the ground/the coax shielding...if it terminates at the antenna base and becomes one with the fender, etc, then the only wire going into the radio's antenna female receptacle is the coax connected to the antenna mast? Or does the ground make the fender connection then lead on to the radio case? 2. No one's commented on the "enhanced antennas" yet. The ones that are sort of hidden up above the rear view mirror. Are they as good or better than the solid mast? If I end up buying a new antenna, I want to get the best possible choice. 3. Besides what's been said, are there any additional layman enhancements I could do...like if the fender is good, why not just continue that ground wire connection right back to the battery ground as well? No time for sleep boys, keep those thinking caps on. Thanks again! Dave

1. Yes, the coax runs from the antenna to the radio. Coax means there's two conductors, the inner, and outer. Since the mount provides a ground, it is referenced back to the radio chassis where it makes contact. That's why you can power up a radio without the ground wire connected with no apparent problems at low volumes. 2. These hideaway antennas can be decent for FM reception as long as there's no metal in the way. However, AM reception is horrible- expect a lot of alternator whine. 3. Yes, there's nothing wrong with this, as you want the mount to be as good a ground as possible.My ex once told me I have a perfect face for radio.

i understand what you're saying now, sparkie. the only thing i was saying is that one reception, being either AM or FM, doesn't need the other in order to operate. example, you can take a radio and unplug the antenna completely, no reception, right. ok, take a length of wire and strip back one end and insert it into the center female antenna recepticle on the radio, now there's FM. absolutelt nothing is connected to the AM side or the radio chassis. grounding the braided sheilding on the antenna coax just provides a better ground than relying on the fender itself which could have rust/corrosion on the mounting bolts, etc.Whatever you do, DO NOT let the white smoke leak out of the wires.....