Looking at sensor 1 gps receivers to hook to my new JD 200 monitor. They range in price from $304 to $422 on ruralking.com the only difference I can tell is the "Hz" rating. They start at 1 and go to 10hz. I need the 4 pin amp connector but I'm unsure which hz I need or does it matter? What affect does it have on operation? Does it have anything to do with refresh rate? Thanks