Yea, it's a BNC.
Actually it's an SMA to male BNC adaptor that comes up through the aluminum bracket then the BNC snaps down on it.
It's all I had to work with and I was bored, but it seems to work ok. When I get my hands on some female N cable end connectors I'm going to try it with that.
Also, I think I may have found the skimmer.
http://www.tmeinc.biz/fryer.htm
It's about half way down the page. It's a 9" but the depth is hard to see from the picture.