Can someone with a MEGA SI unit please turn your unit on, listen closely to the ducer and see if it makes a popping sound? I can hardly hear it thunder but I took a buddy fishing with me this weekend and he kept hearing something pop. I couldn't hear it. He finally determined it was my ducer. Once we got the boat loaded, I turned the unit back on and sure enough it pop, pop, pops.

Sounds like an electric fence charger. Not nearly as loud as an electric fence charger, but the same sound and cadence.

It would start and stop on the water. I don't know a good way to describe this but sometimes the bottom of the lake shows up in the middle of the screen in 2D, instead of close to the bottom of the screen like it should. When the bottom showed up in the middle of the screen, it would pop. When that "false echo" went away, the popping stopped.