CPR PLT OF A BE20 INADVERTENTLY SWITCHES HIS COM FREQ WHEN PAX REQUESTS A TAXI TO MEET THE ACFT. PLT DOES NOT IMMEDIATELY RECOGNIZE THAT HE IS NOT IN CONTACT. WHEN VECTORED HE BELIEVES THE HDG TO BE 130 DEGS WHEN IN FACT IT WAS 030 DEGS. LOSS OF SEPARATION RESULTS.

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I WAS BEING VECTORED FOR AN ILS APCH TO SNA ARPT. I WAS ON A HDG OF 310 DEGS AT 5000 FT. I WAS TOLD I WAS TO BE VECTORED ACROSS THE LOC TO RWY 19R. ABOUT THE TIME I CROSSED THE LOC; I WAS ASKED BY A PAX TO CALL AHEAD FOR A TAXI. IN DOING SO; I SOMEHOW CHANGED THE FREQ ON THE RADIO I WAS SPEAKING TO APCH WITH BY .25 HZ. AFTER 2 OR 3 MINS PASSED WITHOUT HEARING ANY CHATTER; I STARTED LOOKING TO SEE WHAT MIGHT BE WRONG AND DISCOVERED THE #1 COM WAS TUNED TO 121.32 INSTEAD OF 121.30. WHEN I FINALLY GOT BACK WITH APCH I WAS GIVEN A HDG OF 165 DEGS AND A DSCNT TO 4000 FT. I ASSUMED THIS HDG WAS TO INTERCEPT THE RWY 19R LOC. AFTER A COUPLE OF MINS; I WAS GIVEN A HDG OF WHAT I BELIEVED TO BE 130 DEGS; THINKING THIS WAS TO GET ME CLOSER TO THE LOC. WHAT I HAVE NOW LEARNED IS THE HDG I WAS ASSIGNED WAS 030 DEGS. WHAT I ALSO KNOW NOW WAS AFTER 52 SECONDS ON THAT 130 DEG HDG; I WAS TOLD BY THE CTLR 'EXPEDITE YOUR L TURN TO 010 DEGS.' NOTHING MORE WAS SAID REGARDING THIS MATTER AND THE REST OF THE APCH AND LNDG WENT SMOOTHLY. IT WASN'T UNTIL MY DEP 1 HR LATER THAT I LEARNED OF THE PROB AT HAND WHEN I WAS GIVEN A PHONE NUMBER TO CALL WHEN I GOT ON THE GND IN LAS VEGAS. IT SEEMS MY 52 SECONDS ON THE 130 DEG HDG CAUSED A BREACH OF REQUIRED SEPARATION -- WHATEVER THAT IS. I HAVE BEEN TOLD BY THE SOCAL SUPVR ON DUTY LAST NIGHT THAT WHEN THIS OCCURS THEY ARE COMPELLED TO INVESTIGATE AND IF IN FACT THIS BREACH DID OCCUR; THEY MUST FORWARD THEIR RPT TO THE FAA. I GUESS WHAT I TAKE FROM THIS IS A LOSS OF COMS; DEALING WITH A PERSISTENT PAX NEEDING A TAXI; AND NOT KNOWING MY EXACT POS (IN PART DUE TO THE COM PROB); AND MY EXPECTATION TO GET ON THE LOC LED TO A BRIEF MENTAL LAPSE WHERE I SET 130 DEGS ON THE HDG BUG INSTEAD OF 030 DEGS. WHAT REALLY SEEMS ODD TO ME IS SOCAL SAYS THEY HAVE ME ON TAPE READING BACK 'TURN L TO 030 DEGS.'