Why didn't you use a splitter and use the original antenna too?Don't take this the wrong way, I'm not complaining I'm getting way too many FM/AM stations now since I finally got around to experimenting looking for a cure to this problem. I just don't know how to act since my radio on my Tour DCT actually works and acts like a real radio with amazing reception. What a difference an antenna makes. While inside my garage I did an A/B test and switched between the Honda stock antenna and the external and was immediately blown away. An FM station that was unintelligible on the stock antenna was like it was across the street on the external. So at least we know Honda included a receiver that is pretty decent.
As most of you know I did a custom antenna setup on my bike for amateur radio and CB which works really well. I don't use a CB very much so I unscrewed that from the NMO mount and installed a Diamond whip I had laying around. To connect the antenna to the radio I used a Fakra "Z" to SMA cable then into an SMA to N adapter. All of this is using top quality RG400 coax All of this was easy and quick.
My major concern was interference caused by the LED lights knocking signal down. Well, I tested it with lights ON then OFF. Even engine running and I got absolutely no noise and signal stayed strong and clear. I'm glad I can rule my bike out having this problem.
Come this fall I will be designing a hidden antenna that will perform really well and I can screw my CB antenna back on.