alpine hu poor fm reception

I have an Alpine CDE123 HU in a 2002 Dodge Dakota. I ran the deck to factory (non-infinity) speakers for a year using  wiring and antenna adapters from Crutchfield with no problem at all. Then I hooked up and Alpine X300 amp with Polk speakers and my FM reception went way down. On most stations there is a fuzz or static that is consistant with voice or higher frequencies being played. Oddly enough, the strongest stations seem to have as much problem as the weakest stations. The somewhat-distant stations actually play pretty clean. I replaced the speakers with Focals, and changed the RCAs to Stinger (at $100 pricetag!) The problem didn't change. I turned off the IC amp in the deck. I removed the antenna mast to check for corrosion and replaced the adapter that goes from the deck to the Dodge antenna wire. The ground circuit resistance at the deck is 4ohms through factory wiring and the amp is 3 ohms to battery negative. I've heard that Alpine's reception can be poor but before replacing the deck I want to exhaust all other possibilities. BTW, the sound is perfect using CDs or MP3s. Thanks for any advice!

Unfortunately, poor FM reception is common with aftermarket head units, and Alpine is often one of the worst. You can try an antenna signal booster, but it might or might not help.

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Take the fuse out of the amplifier. Did your FM reception come back?

x2 with IAAI. It's not a "poor" reception issue...

IAAI and Oldspark, If it is not a poor reception issue, then what is it? RF interference? If I remove the fuses (there are 2) from the amp I assume there will be no sound from the speakers at all.

Thank you for the advice. I'll try everything to diagnose and fix the problem before throwing money at it :)

wafordtech wrote:

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... a fuzz or static that is consistant with voice or higher frequencies .... the strongest stations seem to have as much problem as the weakest stations. The somewhat-distant stations actually play pretty clean.

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IMO that seems inversely proportional to reception...

It's a pity you can't do as IAAI requested and have the CDE123 output without an external amp. Mine can.

Do you mean run the speakers straight from the deck? I did that with the factory speakers and had no issues. It wouldn't be terribly hard to open the door panels and connect a factory speaker or an old polk to the factory wiring. My thought was that the problem was either the HU not getting a clean FM signal (antenna problem), or the HU was not producing a clean audio-out signal (HU problem). Are you suggesting that the amp is interfering with antenna? You guys know your stuff...I'll try whatever you think will help find/fix the issue.

Thanks Again!

try this, in most dodge vehicles, in the passenger kick panel, there is an antenna linkage that you can see when you take the panel off or it might be farther up high in the kick panel where its hard to see. if that linkage came loose when you were running your wires for the amp then that would cause your loss of fm reception. or maybe is too close to a power or signal wire then maybe its picking up interference that way. also make sure the antenna wire is not pinched or shorted. im no expert on radio interference but i figure its worth a look.

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If this happened right when you installed the amp, I am thinking RFI from the amplifier.   But after reading one of your later posts, it seems as though at that same time you may have run speaker wires into the doors. As stated above, check the antenna union by the passenger door.

I ran 16 gauge speaker wire from the amp under the passenger seat, along the door sill, and out through a rubber grommet below the factory molex connectors to the passenger door. The amp power wire runs through a seperate grommet, and the antenna wire runs through another grommet. All 3 wires are physically parallel to each other and at least a few inches apart. IIRC, running the the amp power and antenna wires close together wasn't problematic, but running the RCAs and antenna wire could cause issues. I didn't believe it was amp interference because not all radio stations are affected. I will check the passenger kick panel area for another loose connection. I didn't know there was a connection between the mast and the HU. I'll dig for it.