LOST COM ON CLIMBING ACR ACFT RESULTS IN CONFLICT.

Narrative

TORONTO CENTER SWITCHED FLT OVER TO CLE CENTER ABOUT 14000' ON CLBOUT AND CLE CENTER CLRED FLT DIRECT TO PSB AND TO CLB TO FL230. AFTER ESTABLISHING INITIAL CONTACT WITH CLE CENTER; NO OTHER RADIO COMS WERE RECEIVED FROM CLE CENTER UNTIL FLT CALLED CLE CENTER CLBING THROUGH FL200 FOR FL230 IN ANTICIPATION OF A REQUEST FOR A HIGHER ENRTE ALT. CLE CENTER ADVISED FLT; AT THIS TIME; THAT THE CENTER HAD LOST RADIO CONTACT WITH FLT FOR SEVERAL MINS AND HAD TO VECTOR ANOTHER ACFT TO AVOID A MIDAIR COLLISION. FLT ADVISED CLE CENTER THAT THE ONLY XMISSION RECEIVED WAS THE INITIAL CLRNC AND THE #1 RADIO RECEIVER MIGHT BE GOING OUT; AND THEN SWITCHED OVER TO THE #2 RADIO. THERE WAS NO FURTHER DISCUSSION WITH CLE CENTER ABOUT THE OTHER ACFT THAT WAS VECTORED TO AVOID THE MIDAIR COLLISION. FLT WAS OPERATING IN VFR CONDITIONS WITH UNLIMITED VIS AND OBSERVED NO OTHER ACFT IN THE VICINITY OF OUR ACFT AND NEITHER DEVIATED FROM THE ORIGINALLY ASSIGNED ROUTE OR ALT CLRNC. AFTER CHKING THE #1 RADIO WITH SEVERAL OTHER CENTERS ENRTE TO MIA; IT WAS CONFIRMED THAT THE #1 RECEIVER WAS UNRELIABLE AND WAS ENTERED INTO THE ACFT LOGBOOK TO BE REPLACED. IT IS VERY DISCONCERTING TO THINK THAT OUR ATC SYS IS SO OVEREXTENDED WITH TFC THAT LOST COMS FOR ONLY A SHORT PERIOD OF TIME MIGHT RESULT IN A MIDAIR COLLISION; EVEN ON AN IFR FLT PLAN.