The radio reception went out on my 2008 XKR, and if I disconnect the coax feed into the amplifier and attach an external antenna to the feed, the reception is great. This means it's either the antenna amplifier, wiring between antenna amplifier, or shark fin antenna that's bad. The wiring looks fine to me.

Has anyone replaced a shark fin antenna before or is it more likely to be the amplifier? For the antenna, does anyone know if you can take the circuitry apart from the antenna housing? I ask because there are lots of them on eBay that don't match the color of mine, so I'd like to swap the internals if it's possible.

I don't know if there's a way to test the amplifier, because it just has a hard wire from it to the antenna, and I assume it's more than a coex/standard antenna signal?

 

The radio (if you’re talking about AM/FM) antenna on your 2008 is not in the shark fin, but is actually in the spoiler, near the brake light LEDs.

 

Oh interesting. Is the shark fin for the GPS or navigation?

If it's within the spoiler, that'll sure make it easier. Is it a more traditional antenna that is unlikely to break?

 

The shark fin is for the satellite radio. Here’s your am/fm antenna;

 

This post is gonna save some people a lot of money and time chasing the wrong part.
thanks KJ!