How to get a nuke in MW2......?

I average 15-20 kills a game with 5-10 deaths a game I use scarch with silincer my kill streaks are predator missle,harrier,chopper gunner but I want to get a nuke and once I used harrier, chopper gunner, nuke and I had the harrier but these noob tubers who can only kill my god damn harriers shot it down and knifed me in the back so damn close but any tips to help me get a nuke and who you do it