HS125 STRAYED FROM MIDWAY STAR AND ENTERED ORD CLASS B AIRSPACE.

Narrative

WE WERE CLRED TO DEPART VIA THE MIDWAY 4 DEP OFF RWY 4L AT MDW. I COPIED CLRNC AND SET UP 109.9 IN THE VOR/DME FOR THE TURN AS ASSIGNED BY TWR. I DID NOT NOTICE THAT MY DIRECTOR OF OPS WHO I WAS FLYING WITH RESET THE VOR DME'S TO ANOTHER FREQ. I BELIEVE AN ENRTE VOR WHILE I WAS IN THE FBO MAKING A PHONE CALL. I SAW HIM LOOK OVER THE SID AND ASSUMED HE KNEW WHAT HE WAS DOING; BUT I DID NOT NOTICE THE FREQ CHANGE. ON THE RWY THE TWR GAVE US R TURN HDG 250 DEGS WHICH I READ BACK AS A L TURN. THEN WE DEPARTED WE HAD TO CLB TO 2400 FT ON 100 DEG HDG THEN L TURN 250 DEGS LEVEL AT 3000 FT. I INITIALLY WAS QUESTIONING THE L TURN BECAUSE I KNEW ORD TCA IS CLOSE; BUT KNEW I READ IT BACK CORRECTLY. WE CLBED SLOW NOISE ABATEMENT WISE AND FINALLY TURNED TO 100 DEGS AT WHICH POINT MY ATTN WENT TO THE DME; WHICH READ NOTHING. I ASKED THE PF WHAT HE WAS USING FOR THE TURN AND GOT NO REAL ANSWER AT WHICH POINT I DIALED IN 109.9 TO FIND OURSELVES ABOUT AT THE 4.0 DME. WE GOT TO 4.8 THE WHOLE WHILE I'M BARKING AT THE PF TO TIGHTEN THE TURN. THE CTLR CAME ON TO ASK OUR HEADING AND I REPLIED L TO 250 DEGS AS ASSIGNED. HE CAME BACK YOU OUGHT TO READ THE SID. NOT KNOWING IF IT MIGHT HAVE BEEN SOME OTHER MIX UP AND KNOWING WE NEED TO RESOLVE THIS QUICKLY I ASKED FOR A RADAR VECTOR. HE WAS AFTER US FOR WHAT I THOUGHT HE WAS THE 4.0 DME. BUT I WANTED THE QUICKEST RESOLUTION POSSIBLE; NO TIME TAKEN UP IN QUESTIONS. WE LATER DISCUSSED THE SIT AND THE PF SAID THAT HE THOUGHT THE LOC WAS LEFT IN FROM THE APCH AND ARR; AND WENT WITH STANDARD OPS TO SET IN THE FIRST NAV ENROUTE. HE IS MY BOSS AND THERE IS A HESITATION NOT TO BE A SCREAMING MOMMY AND PLAY MORE LOW KEY; PORTRAYING THAT HE IS EXPERIENCED ENOUGH TO KEEP HIMSELF OUT OF TROUBLE. MY LESSON LEARNED IS TO NEVER TAKE ANYONE'S FLYING FOR GRANTED; TO FOLLOW UP ON EVERY DETAIL. AND I GUESS ONE LAST LOOK AT THE WAY THE NAVS ARE SET UP PRIOR TO TAKING THE RWY WILL SAVE A LOT OF CONFUSION AND SAVE ANY NEED FOR RESOLUTION. I AM VERY SHARP AND CAN'T BELIEVE THIS GOT PAST ME. IT CERTAINLY WILL NOT AGAIN.