Lose radio presets/clock setting when interior lights come on.

[Highway Star]

When I set my radio station presets and clock I lose the settings every time the interior lights come on (opening door etc). It's a '79 Coupe with original AM/FM. Tried another radio (same but has 8-track), and still has the same problem. Anyone know the remedy for this?

[Highway Star]

Problem solved. Strange as it may sound, it was a 20 amp fuse for the clock/lighter. Apparently the circuit interacts with the radio as this was the first year ('79) for the clock to be incorporated into the radio. Just got the car recently, and hadn't gotten around to checking all the fuses.