[Boatanchors] What Kind of Connector?

[Keith Densmore]

Hello All,
I have a piece of English  gear with a type of coax connector I am not 
familiar with. It sort of looks like an over sized BNC connector except the 
outer shell is not smooth it is  threaded, somewhat like a an SO 239. The 
diameter  of the connector is about 1/2 inch. I've seen these before but not 
sure what it is called. I can email a pix if there is a good connector 
identifier on board.

Thanks for the help, best for 2012,

Keith ve3ts