More electrical woes

This electrics are driving me nuts!!! When I have my radio on and driving everything is fine as soon as I apply the brake the radio restarts but only sometimes. The radio sometimes restarts when I use my indicator and sometimes when I flick on my spotlight switch. The fault is intermittent and annoying does anybody have a clue as to what this may be. The radio is wired through the ignition I believe so it comes on when I start up. It seems like ther is not enough power to work everything?????

Sounds more like radio earthing problem , trying to resolve wiring problems over the net is similar to trying to juggle jelly

If not an earth fault, could be a dodgy ignition switch