RPTR PERCEIVES A NEAR MISS IN THE VBG TFC PATTERN.

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WHILE PERFORMING PROFICIENCY TKOFS AND LNDGS AT VBG UTILIZING RWY 30; R-HAND TFC PATTERN ALT 1400 MSL. UPON DEPARTING ON A HDG 015; I CALLED VBG TWR TO CONFIRM MY POS 'TURNING R XWIND;' THE TWR RESPONDED; 'RPT ON BASE.' PROCEEDING DOWNWIND AT 1400 FT MSL; I OBSERVED A MIL HELI ACFT APPROX 500 FT BELOW AND 800 FT HORIZ COMING TOWARD ME; HDG FOR THE HELIPAD. I TURNED ON MY LNDG LIGHTS AND TURNED MY ACFT APPROX 15/20 DEGS L TO ASSURE SUFFICIENT CLRNC BTWN MY ACFT AND THE HELI. WITHIN A COUPLE OF MINS I PASSED THE HELI ON MY R AND STILL MAINTAINING APPROX 1400 MSL AND LOST SIGHT OF THE HELI PRIOR TO REACHING THE BASE LEG FOR RWY 30. I PROCEEDED TO TURN R TO A HDG APPROX 210 DEGS TO RPT ON BASE AS PER MY LAST INSTRUCTIONS FROM THE TWR CTLR. I CALLED THE TWR THAT 'ON BASE FOR LNDG RWY 30.' ALL I HEARD WAS THE WORD 'CLR.' IN THE DISTANCE; APPROX AT 11 O'CLOCK; A WDB ACFT WAS SLOWLY CLBING AND APPEARED NOT TO BE A FACTOR FOR ME TO COMPLETE THE TOUCH AND GO SAFELY. TURNING R TO HDG 300 DEGS I CALLED THE TWR 'ON FINAL RWY 30 FOR TOUCH AND GO.' NO ACKNOWLEDGMENT FROM THE TWR. HEARING THE WORD 'CLR' PRIOR TO TURNING ON FINAL I PROCEEDED TO CONTINUE TOUCH AND GO OP. I FEEL THAT THE TWR CTLR WAS PREOCCUPIED WITH THE HELI AND THE WDB AND FORGOT THAT I WAS THERE. FAILED TO PROVIDE ADEQUATE CLRNC FROM THE HELI AND FAILED TO MAINTAIN POSITIVE COM WITH MY ACFT.