DIVERSION TO ALTERNATE AFTER LOSING 2-WAY COM WITH CTR.

Narrative

I DEPARTED LGD; OR; ENRTE TO HUF; IN; WITH A FUEL STOP IN CYS; WY. IFR AT 21000 FT. SHORTLY AFTER LEVELOFF AT 21000 FT I WAS UNABLE TO REACH ZLC OR RECEIVE ON ANY FREQ. THE COM RADIOS WERE DEAD. I PROCEEDED ON TOP OF A MOSTLY OVCST LAYER WITH MOUNTAIN OBSTRUCTION. I AM FAMILIAR WITH THE PLAINS AREA E OF DENVER BUT NOT WITH THE TERRAIN IN THE AREA OF CHEYENNE. THERE WERE BREAKS IN THE OVCST SE TOWARD THE DENVER AREA; AND I PROCEEDED IN THAT DIRECTION; PREPARING TO LET DOWN OVER THE PLAINS; THEN THE CHEYENNE AREA. I FOUND AN AREA LARGE ENOUGH TO MAKE A VISUAL DSCNT; LEVELING OFF ABOUT 30 MI E OF FTG AND PROCEEDING BACK TO LAND AT FTG. UPON TOUCHDOWN MY RADIOS CAME ON AND I COULD HEAR ANOTHER ACFT ON THE UNICOM FREQ. THE RADIOS THEN WORKED NORMALLY AS XMIT AND RECEIVE RADIO CHKS. I FLEW THE REMAINDER OF THE FLT WITH NO OTHER PROBS. IT IS DIFFICULT TO FIX AN ELECTRONICS PROB THAT IS INTERMITTENT AND NOT MALFUNCTIONING AT THE MOMENT. WHAT I THINK HAPPENED WAS THE AUDIO PANEL SPEAKER/PHONE TOGGLE SWITCH WAS NOT FIRMLY SEATED IN THE PHONE POS. I HAD MOVED THE INDIVIDUAL RADIO TOGGLE SWITCHES TO THE ALTERNATE POS BUT NOT THE MASTER SPEAK/PHONE SELECTOR. THAT SWITCH MAY HAVE BEEN SLIGHTLY OFF ITS FULL DOWN POS. APPARENTLY; WHEN RADIO FAILURE OCCURS I NEED TO MOVE EVERY POSSIBLE SWITCH TO CHK ITS FUNCTION.