ACFT HAS UNCONFIRMED TCASII RA AT 1500 FT AND LATER OVERSHOT ASSIGNED ALT BY 1000 FT.

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ALL PREFLT AND TKOF ACTIVITIES WERE NORMAL UNTIL WE WERE AIRBORNE APPROX 1500 FT AGL WHEN THE ONBOARD TCASII ACTIVATED AN RA TO 'MONITOR VERT SPD' AND INDICATED TFC 600 FT BELOW US. AT THIS TIME WE WERE IMC AND UNABLE TO CONFIRM TFC VISUALLY. THE SUDDENNESS OF THE TFC WARNING AND LACK OF VISIBILITY WAS A LITTLE UNNERVING. I IMMEDIATELY CONTACTED ATC TO VERIFY WITH AND INFORM THE CTLR OF OUR RA. AT THIS SAME TIME WE WERE ENCOUNTERING ICING CONDITIONS AND BEING CAUGHT UP IN THE WAKE TURB OF AN LGT SOME 5 MI AHEAD. WHEN WE CLBED THROUGH APPROX 8000 FT WE BROKE OUT OF THE CLOUDS TO A BRILLIANT AFTERNOON SUN DIRECTLY IN OUR FACE. GOING THROUGH 8000 FT THE FO MADE PREPARATIONS ON THE FLT GUIDANCE SYS TO ACCELERATE THE ACFT TO 320 KTS ONCE WE LEVELED AT 10000 FT. AT THIS TIME HE NOTED THAT THE ALT ARMING WINDOW WAS SET FOR 12000 FT. WITH ALL THE ACTIVITY THAT HAD TAKEN PLACE SINCE TKOF; HE THOUGHT THAT HE HAD MISSED NEW CLB INSTRUCTIONS TO 12000 FT. I WAS ON THE ATC RADIO AT THIS TIME RECEIVING AND READING BACK TURN INSTRUCTIONS; SO HE WAS UNABLE TO CONFIRM THE ALT CLRNC WITH ME. I WAS ALSO CHKING OUR TCASII EQUIP TO SEE IF IT WAS WORKING PROPERLY. AS WE APCH 10900 FT; THE DEP CTLR INQUIRED ON OUR ALT AND STATED WE WERE ONLY CLRED TO 10000 FT. WE BEGAN A LEVEL OFF AND DSCNT WITH OUR ALT PEAKING AT 11000 FT. THE CTLR QUICKLY TOLD US TO REMAIN AT OUR ALT AND SUBSEQUENTLY CLRED US TO 14000 FT.