AIR TAXI PLT HAS FREQ COM PROB RESULTING IN ALTDEV.

Narrative

I WAS FLYING AN AEROSTAR. I HAD ONE PAX IN THE BACK AND A COPLT IN THE R SEAT. MY ASSIGNED ALT WAS 3000 FT AND I WAS BEING VECTORED FOR A VISUAL APCH. THE GUY IN THE R SEAT WAS TALKING ON THE RADIO. THE CTLR HAD US ON 124.1 WHICH ISN'T A GOOD FREQ FOR THAT AREA. WE SHOULD HAVE BEEN ON 118.4. WE WERE IN AND OUT OF THE CLOUD BASES UNTIL WITHIN ABOUT 5 MI OF THE ARPT. AT THAT POINT WE BROKE OUT AND HAD THE ARPT PLAINLY IN VIEW. THE COPLT CALLED ARPT IN SIGHT. THE RADIO WAS BREAKING UP. I UNDERSTOOD WE WERE CLRED FOR THE VISUAL APCH AND STARTED MY DSCNT. THEN I HEARD THE CTLR SAY MAINTAIN 2800 AND REALIZED HE HADN'T CLRED ME FOR THE VISUAL AND COULDN'T HEAR US. I LEVELED AT 2500 FT AND CALLED COLUMBIA TWR FOR APCH CLRNC. THEY CLRED ME FOR THE APCH. THERE WAS NO PROB EXCEPT MY LEAVING MY ASSIGNED ALT IN THE CONFUSION. I FEEL THIS WOULDN'T HAVE OCCURRED IF WE HAD BEEN ON THE RIGHT FREQ OR IF I HAD BEEN TALKING TO CTR MYSELF. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THE TROUBLE WAS THAT HE WAS ALLOWING A FRIEND AND FELLOW PLT TO DO THE RADIO WORK. HAD HE BEEN ON THE RADIO HE WOULD HAVE SIMPLY SWITCHED TO THE 118.4 FREQ FOR COM. THAT IS ANOTHER CTR FREQ; BUT WITH DECENT RECEPTION IN THE AREA. HE FEELS THEY HAD JUST GONE BEYOND THE SECTOR INVOLVED WITHOUT A HDOF. HE ADMITS HIS ERROR IN DSNDING TOO SOON.