Topband: Soldering radials etc

[Merv Schweigert]

I wonder if someone could point me in the direction of where
to buy and what to use to solder radial wire.  I also have some
4 inch copper strap I need to join and solder. 
Anything soldered with regular solder goes to white powder
in a couple months here. 
I know of cadweld to weld ground rods to wire etc. 
I have another field of radials that I need to connect and use.
Thanks  73 Merv K9FD/KH6