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Poor AM reception


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daveward 
Member - Posts: 15
Member spacespace
Joined: April 05, 2006
Posted: November 14, 2006 at 10:39 AM / IP Logged  
I'm hoping all the knowledge on this forum can focus on AM radio for a moment. While the amplified tunes from my FM or CD are really great, all I really want to do (day-in, day-out) is listen to talk radio.
AM reception is my ISSUE.
I'm putting a known-working Pioneer head unit in my 1989 F350 work truck. I connected it to a new out-of-the-box Pioneer speaker and to the antenna. Using the accessory key position (the truck engine isn't even on) the AM radio puts out pure static. So much it drowns out the am radio talk. FM radio is OK. I have the antenna well-grounded.
Can someone point me to a solution? Thanks. Dave
the12volt 
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Administrator spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spaceThis member has been recognized as an authority in Mobile Security and Convenience. Click here for more info.spacespace
Joined: March 07, 2002
Location: Louisiana, United States
Posted: November 14, 2006 at 10:49 AM / IP Logged  
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.
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spookiestylez 
Silver - Posts: 531
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Joined: September 23, 2005
Location: Virginia, United States
Posted: November 14, 2006 at 11:22 AM / IP Logged  
Maybe look into getting an amplified antenna.
sS
rtfm
sparkie 
Platinum - Posts: 2,061
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Joined: November 06, 2003
Location: Canada
Posted: November 14, 2006 at 4:59 PM / IP Logged  
Disconnect the negative battery cable. Use a digital meter to measure the ground of the radio with the antenna unplugged. Measure the ground of the antennas outer shield to ground. Both readings need to be less than 0.5 ohms or you will have a problem. If all tests OK try using a test antenna to see if the reception improves. If it does, replace the antenna. If not you may need a new radio. Even brand new ones sometimes have a problem.
sparky
soultinter 
Copper - Posts: 170
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Joined: January 16, 2004
Location: United States
Posted: November 14, 2006 at 5:20 PM / IP Logged  
I'm pretty sure that almost all aftermarket radios are poor am radio receptors, gues it has something to do w the way they are made, more of the circuitry id dedicated to fancy graphics, reading wma/mp3 files etc. and less of an emphasis on am reception. I was told that by a company rep, and i have seen it repeatedly, am always suffers compared to a factory radio.
daveward 
Member - Posts: 15
Member spacespace
Joined: April 05, 2006
Posted: November 15, 2006 at 10:04 AM / IP Logged  
Good morning guys, thanks for the responses...I would have replied sooner but I had some trouble with the forum recognizing me. Don't they know a VIP when they see one? Yuck, yuck.
Anyway, thanks again and I'll try the ideas suggested. Here are the questions related to that:
1. spookiestylez....I've read about the "enhanced antenna's...I'm always on the search for newer and better...are these really better? The ones mounted horizontally to the inside of the windshield?
2. sparky....Re: "Use a digital meter to measure the ground of the radio with the antenna unplugged..." Do you mean: is the radio's ground wire actually grounded...how else would I measure the radio's ground's effectiveness? And re: "Measure the ground of the antennas outer shield to ground." Here, do you mean the antenna pole itself, or the shielding on the wiring?
Again...thanks. Dave
1lowgalant 
Copper - Posts: 116
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Joined: September 15, 2005
Location: United States
Posted: November 15, 2006 at 5:27 PM / IP Logged  
FM runs through the mast of the antenna while AM uses the base, or the grounded part of the antenna. check to see if the base of the antenna that is actually touching the fender has rusted or isn't getting a good connection. this is why using a DMM helps. something that can help is if you're sure the antenna is getting good connection to the fender, connect a ground strap from the fender to the negative battery terminal. also, you can strip back a little of the insulation on the antenna coax behind the radio and attach a length of wire around the braided wire on the coax and then connect the other end to chassis ground. this has worked for me in the past.
Whatever you do, DO NOT let the white smoke leak out of the wires.....
sparkie 
Platinum - Posts: 2,061
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Joined: November 06, 2003
Location: Canada
Posted: November 15, 2006 at 6:40 PM / IP Logged  
I'm sorry to disagree with you flowgalant, but the antenna mast and ground plain both receive the transmission signals for AM and FM. Antennas are optimized for FM reception because it has better sound. Dave. Use a meter to measure the grounds. First disconnect the antenna cable from the back of the radio. Set your meter for a low resistance scale. Place your black probe on a piece of the vehicle chassis that is bare metal. It must be one the car body and not on a steel bracket in the dash. Bare a small section of the radio's ground wire close the radio. Put your red probe on the bare wire. The meter should read less than 0.5 ohms. Do this test with the ignition off. Next move your red probe to the antenna cable. It has a center pin and a outer metal sleeve on the end where it plugs into the radio. Put your red probe on the outer sleeve. Again your reading should be less than 0.5 ohms. If either the radio or the antenna has a poor ground, you must repair the ground where it terminates and not in the shielding as mentioned elsewhere. The antenna grounds where it is mounted usually. Clean up any metal to insure it has a good ground. The ground of the antenna is vital. The fender which it is grounded to receives half the incoming signal, the other half being received through the mast. A final measurement should also be taken. Place your red probe on the antenna mast and the black on the center pin of the antenna lead at the radio. You should again get a reading of less than 0.5 ohms. Post your results if all checks out OK and I can give you more things to check.
sparky
i am an idiot 
Platinum - Posts: 13,666
Platinum spaceThis member consistently provides reliable informationspace
Joined: September 21, 2006
Location: Louisiana, United States
Posted: November 15, 2006 at 6:57 PM / IP Logged  

      If you are listening to AM you really need to stick with the factory radio.  You will never get an aftermarket radio to even come close to working on AM.  The reason for that is they put no money into the am section.

1lowgalant 
Copper - Posts: 116
Copper spacespace
Joined: September 15, 2005
Location: United States
Posted: November 15, 2006 at 7:09 PM / IP Logged  
really, sparkie? so technically i could wrap a peice of wire around the outside braided wire part of the coax and then insert the other end into the center hole in the receiver and get FM reception? didn't think so. again, the mast, which is the center conductor in the coax, is for FM and the base, which is the braided wire surrounding the center part, is for AM. ever grounded the braided sheilding the chassis ground and got better FM reception? i bet not, but i bet AM was better.
Whatever you do, DO NOT let the white smoke leak out of the wires.....
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