AM radio sounds terrible in 97 f150

[ZMan]

My dads 97 f150 seems to be having a little trouble with the am radio. It is extremely staticy, and is affected by anything else electrical on the truck. Like if you have the blinker on it clicks, or if you roll the window up/down it makes an aweful noise. Its a factory cassette radio, has no problems with fm.

 

[85_Ranger4x4]

Sounds like a bad ground to me.

 

[adsm08]

Try replacing the ignition capacitors. When they go bad the most noticeable symptom is frequently reception issues with the AM radio.

They are pretty cheap and easy enough to replace.

 

[cody93]

yea, its capacitors for ignition or sheilding. AM radio is extremly supseptable to pulse fequencies, like ignition coils wich produce strong RF frequencies too.

 

[Ranger SVO]

Typically, when we have noise on AM, its an antenna problem. Check the antenna, make sure the base is mounted properly. The ground at the base of the antenna is where a majority of AM noise rejection takes place.

We would test this at the shop I worked at by temporarily hooking up another antenna and grounding it somewhere on the body. And 99% of the time, noise problem was solved. So the antenna got replaced.

One other thing I always did with AM noise problem was to ground the chassis of the radio to something metal on the vehicle.

 

[shane96ranger]

Typically, when we have noise on AM, its an antenna problem. Check the antenna, make sure the base is mounted properly. The ground at the base of the antenna is where a majority of AM noise rejection takes place.

OK..... just a question here. I've always understood that the AM antenna is internal, and the FM antenna is external. Have I had this misunderstanding for YEARS?

 

[cody93]

for your pocket radios,alarm radios and boom-boxes and what not then yea, they have an antenae like this

but the one in your ride gets its input from the FM antenae also. dont believe me, go unplug your antenae from ur radio and see if AM works

 

[adsm08]

go unplug your antenae from ur radio and see if AM works

That gives me an idea that I really should have had before.

Turn everything else in the truck off. The engine, the fan, the lights, all of it.

See if AM reception gets better. I have some shielding issues with the antenna cable on my B2. My capacitor is new but my FM reception, especially when at extreme range to the transmitter, gets much better when I shut the engine off.

 

[Ranger SVO]

Both FM and AM needs the antenna, only AM is really picky. AM or Amplitude Modulation works by by varying the strength of the transmitted signal in relation to the information being sent. The problem with this type of signal is that it is subject to interference. The vehicles computer, the alternator, the ignition can all interfere with the AM signal. Especially if the antenna shield is not properly grounded.

FM is a lot less picky. In a few show cars (no antenna), I've used just a piece of wire under the dash about 9 ft long. FM reception was perfect, AM was not. When we have an FM reception problem its usually a radio problem. Radio problem includes a good ground. Again, (back when I did installs), I always grounded the radio chassis to something metal on the vehicle.

 

[ZMan]

Ya i should have added that, its fine with the truck turned off. So its a possibility something is wrong with the antenna?