Hi Wendell. As you know I just upgraded to the TNR also. I have no problems with calibration. It shows me right where I am. I don't get the GPS warning often at all. Generally going under a bridge, etc. If you're getting that a lot something must be wrong. Go to my thread for a picture of my antenna location...three inchs back from the windshield should be fine.
http://elcova.com/groupee/forums?a=tpc&s=2826088551&f=6706011751&m=709104869 If it was me I'd check all connections and if you have the same problem better talk to who you bought it from. Hope this helps.