Radio volume problems

[MortyStewart]

I am having a radio problem with my 84 aspencade. I wonder if it is a voltage problem. I got the bike this year put in a new battery and would listen to the radio while I worked on the bike. I finally got it running and took it out for a spin. After about 10 minutes the radio quit working . I found that if I pulled the brake just enough to turn lights on that radio would work until I let go of the brake lever and the radio would die. So I started down the road at about 55 and the Radio doesn't work. I hit the kill switch and pulled the clutch so that the stator quit turning and the radio came on. I then let the clutch out to let engine turn over and the radio dies. it almost acts like it is not liking voltage over about 12.75. I let it idle in the Yard with the lights on bright and voltage at idle is about 12.5 and the radio comes on. If I speed up the engine- voltage comes up and radio dies. Help me I need Ideas

[neoracer]

that is a strange situation,we are talking about a stock panasonic radio correct?