Wavering Lights?

Noticed that all my lights seem to waver in their output, especially when just starting up.

The lights don't go out, the intensity just seems to pulse rhythmically at about 2-3 pulses per second.

It affects the gauge lighting as well as the headlamps.

The battery is fairly new and cables are clean with no sign of corrosion.

Charging seems fine.

Is it alternator time? Is there an external voltage rectifier or regulator?

Thanks!

On a cold start mine has always flickered a little when the air pump cycles, but it it's doing it consistently after warmed up somethings wrong. I'd put a digital volt meter on it while running - should be about 14V. The regulator is inside the alt. A battery load test isn't a bad idea either, just to eliminate it - most parts stores will do it free.