Is this normal for Badger 200NH airbrush?

Eric, I'm sure someone would have given you an answer. It takes time for the right people to get to questions, sometimes. I didn't feel like I was experienced enough to give you a definite answer, but my guess is that you are seeing the pulse created by your air compressor. My guess is that you don't have an air tank so your compressor is driving air directly to the tip of the brush. If I understand correctly, the piston drive in the compressors have this pulse in them as the piston makes its full travel. Iwata tankless compressors, which is what I have, overcome this by sending the air through a long hose before it gets to the tip of the air brush. This seems to have the effect of reducing the intensity of the pulse. So, if you don't have a tank or a long air hose, you are going to see that pulse. Have I described your compressor accurately?

No, it is not normal for the 200NH to pulse every 3 seconds.  Is it the air flow that pulses, or just paint?  If you blow plain air, can you feel any pulsing with your finger in front of the nozzle?  Do the pulses change in any way as you pull back the trigger?

Don

It's hard to tell if it does that with just air because it pulses so quickly. But I want to say it does that with paint (water and thinner too). Adjusting the back needle for flow doesn't seem to matter.

It might be the needle bearing.  If it leaks, bubbles of air can be sucked into the body and cause pulsing.  If that's the case, it won't happen if the airbrush is held upside down, because there will be a slight pressure rather than a vacuum in the body.  Or, you could put some water in the 1/4oz cup and tilt the airbrush to the right so that the water level is higher than the body.  If the problem goes away, it could be the bearing.  Do you feel a little drag if you pull the needle out?

Another possibility is a slight leak where the cup fits into the body.  Does it do it with both a cup and a bottle?

Don