I've been working a problem with the radio on my road glide 05 for the past 4-6 weeks. The problem - within approximately 4 minutes of running the radio or CD at high volume (high enough to hear when running above 55 mph) the sound from the speakers begins to drop momentarily, sometimes for as long as a second or two but usually much less, but very noticeable. Stock speakers or hog tune speakers - same result. BTW - Pez is great to work with and he's been trying to help me with this problem even sending me resistors to change the impedance to get closer to the that of stock. I also began an exchange with John from Radio Sound - another great guy to work with. All in all, I was suspecting an overheat problem with the radio causing the thermal protection circuit to actuate and cause a drop in power. And it seems that several road glide owners were complaining to Pez and John as well but not electra glide owners. Well it looks like the radio mounting frame on the road glide is very conformal to the radio, much more so than the electra glide, and that this conformality is possbily interferring with heat removal.

Here's what John from Radio Sound wrote:
The radio getting hot when operating at elevated volume levels is normal. The symptom of the audio cutting in and out does seem to be more common on Road Glide model bikes. As you mentioned, the radio carrier severely limits air flow over the radio's heatsinks and is likely why the problem in more prevalent on the Road Glides in comparison to the Electra Glides which uses a different mounting for the radio and allows air flow around it. The bottom of the Electra Glide faring is open which allows air to flow in around the radio somewhat. On the other hand, the Road Glide faring is sealed for the most part and there is no way that air can flow around the radio to cool it. This is the most likely reason that this problem occurs on the Road Glides and not so much on the Electra Glides.

also John had me check the starter relay and battery hold down clamp arrangement:
The starter relay can be affected by engine vibrations particularly at high RPM shift points if the battery hold down clamp is in contact with the relay. The starter relay supplies the switched voltage supply to the radio. The effect of vibrations on the relay would result in the radio turning off and on like the ignition switch off and on does.

In any case, it appears (not scientific) that us road glide owners are stuck with this problem, or at least some of us are. I didn't really notice the problem until I started running the radio at 3/4 or higher volume levels and for extended periods of time and I really noticed it when I got the hog tune speakers since they sounded so much clearer and louder it was easier to notice the sporadic drop in sound.

Thanks again to Pez of hog tunes and John from Radio Sound for all their investment in time. They both are great to work with.

One thing I'm really good at now - installing the fairing.

Now if I can only get Harley to give all us road glide owners a free amp to reduce the power output level required from the radio keeping it cooler............................hmmmmmmmmmmmmm!

 

Then the amp would probably over heat .. we just can't win!! [8D]

 

I had the same problem on my 06 Road Glide. Mine was a rediculously easy fix! Check the antenna connection. There is a star washer on the antenna mount and it is adjustable with two nuts, one on top, one on the bottom. I found my solution when I added the tour pack. The connector is just a little too short and I had to take off that star washer for the center lead inside to make a solid connection. Once I did that, never had another problem. Seems too simple but it solved my problem that sounds identical to yours. Hope it helps.