LOSS OF RADIO CONTACT - PLT TECHNIQUE COM.

Narrative

HAD JUST BROKEN VFR ON A NIGHT FLT. WE WERE IN COM WITH THE APCH CTLR WHO ISSUED US A LOWER ALT (4000 FT) AND A VECTOR TOWARDS OUR DEST (ABOUT 25 MI AWAY). AT THE TIME WE WERE FLYING IN (OR ABOUT TO ENTER) CLASS B AIRSPACE. THE PAX IN THE R SEAT WAS ALSO AN IFR-RATED PLT SO HE WAS HELPING WITH SOME OF THE RADIO SELECTION. WE SWITCHED #2 COM TO LISTEN TO THE ATIS DEST WHILE STILL USING #1 COM AS A PRIMARY. WHEN WE SWITCHED AWAY FROM THE ATIS; MY 'COPLT' INADVERTENTLY MOVED THE SPEAKER/PHONE SELECTOR TO THE MIDDLE (NEITHER SPEAKER NOR PHONE) POS. IN THE DARK COCKPIT THIS WAS NOT VISIBLE. WE BRIEFED THE APCH (ALTHOUGH VFR); BUT HEARD NO FURTHER INSTRUCTION FROM THE APCH CTLR. AFTER 2-3 MINS I FELT SOMETHING WAS WRONG AND XMITTED ON BOTH RADIOS; ONLY TO FIND OUT THAT THEY WERE APPARENTLY INOP. WE THEN CONTACTED THE APCH FACILITY ON OUR HANDHELD RADIO. WE WERE TOLD THAT THEY HAD BEEN TRYING TO REACH US FOR 10 MI. WE WERE ISSUED 2300 FT AND SUBSEQUENTLY CLRED TO LAND. WHILE ALL THIS WAS GOING ON I KEPT TROUBLE-SHOOTING THE RADIOS. WHEN TAXIING CLR OF THE RWY I FOUND THE SELECTOR TOGGLED IN THE MIDDLE POS. SUGGESTIONS: ALLOW OTHERS TO SELECT RADIOS ONLY IF THEY ARE VERY FAMILIAR WITH THE PARTICULAR SETUP. THE MANUFACTURER SHOULD ELIMINATE THE MIDDLE (DEAD) TOGGLE POS ON THE SELECTOR. IT SHOULD ALWAYS BE EITHER ON SPEAKER OR PHONE.