DEPARTING SMA UNABLE TO HEAR DEP CTLR CLRLY. MISSES ALT IN CLRNC. ALTDEV.

Narrative

DEPARTING TPA ON IFR FLT PLAN ('RADAR VECTORS; 1600 FT; EXPECT 6000 FT IN 10 MIN'); TWR GAVE US A HDG OF 060 DEG AND INSTRUCTED US TO CONTACT APCH (120.65). WE CALLED APCH AND RPTED OUT OF 500 FT FOR 1600 FT. TAMPA APCH ANSWERED AND WERE VERY WEAK AND UNREADABLE. WE CHANGED TO #2 RADIO AND ASKED FOR A REPEAT. TAMPA WAS STILL WEAK BUT WE COULD HEAR OUR CALL SIGN AND AN ALT; WHICH SOUNDED LIKE 6000. WE ROGERED 'CLBING TO 6000' AND CONTINUED OUR CLB. PASSING THROUGH 3000 FT; APCH CALLED US AND INFORMED US WE WERE ONLY CLRED TO 1600. NO TFC CONFLICTS HAD OCCURRED. 5 DAYS LATER; WE HAD ANOTHER TRIP TO TPA AND DEPARTING WERE GIVEN THE SAME DEP CLRNC. AGAIN; SWITCHING FROM TWR TO DEP; WE FOUND DEP TO BE EXTREMELY WEAK AND DIFFICULT TO UNDERSTAND ON 120.65. WE REMARKED ON THIS; AND THAT WE HAD DIFFICULTY BEFORE -- AND WERE INFORMED THAT THIS WAS NORMAL BECAUSE THAT FREQ'S ANTENNA IS LOCATED IN LAKELAND (33 NM AWAY). CORRECTIVE ACTION: DO NOT ASSIGN 120.65 TO DEP WHEN STILL AT TOO LOW AN ALT TO RECEIVE FROM THIS ANTENNA.