AN IFR C172 IN IMC EXPERIENCES LOST COM WHILE ATTEMPTING TO CONTACT APCH CTL. THE PLT SWITCHED XPONDER TO 7600 AND CONTINUED ON FILED FLT PLAN AT 6000 FT. WHEN VMC WAS ENCOUNTERED; THE PLT SQUAWKED 1200 AND LANDED AT CLOSEST ARPT WITHOUT FURTHER INCIDENT; THEN CONTACTED APCH CTL AND CANCELED IFR FLT PLAN. HOWEVER; THE CANCELLATION WAS NOT RELAYED TO FSS AND AN OVERDUE ACFT SEARCH STARTED.

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WHILE ON IFR FLT PLAN FROM BVY TO 39N; LOST BOTH COM RADIOS AFTER HARTFORD DEP CTL ADVISED TO SHIFT FREQ TO CONTACT NY APCH CTL. COULD NOT RAISE NY APCH CTL AND AFTER REVERTING TO PREVIOUS HARTFORD DEP FREQ; COULD NOT RAISE ATC THERE EITHER. AFTER FAILING TO RAISE NY APCH ON OTHER FREQS AS LISTED IN ARPT FACILITY DIRECTORY AND ANY STATION ON 121.5; ATTEMPTED TO TROUBLESHOOT RADIO PROB BUT CONCLUDED XMITTERS HAD FAILED. SWITCHED XPONDER TO 7600 AND GUARDED VOICE FREQ ON NAV RADIO FOR SAX VOR WHICH WAS NEXT POINT ON IFR CLRNC. PROCEEDED IFR IN IMC IN ACCORDANCE WITH LAST CLRNC UNTIL APPROX 20 NM E OF HUDSON RIVER AT WHICH TIME VMC WAS ENCOUNTERED. DSNDED VFR TO 2500 FT AGL AND SWITCHED XPONDER TO 1200 AND LANDED AT NEAREST ARPT; GREENWOOD LAKE (4N1). CALLED NY TRACON VIA LAND LINE TO ADVISE ON GND AND TO VERIFY IFR FLT PLAN HAD BEEN CLOSED. ALSO ADVISED FBO AT 39N. HOWEVER; LATER THAT NIGHT; LCL POLICE CHKED 39N FBO REGARDING OVERDUE AIRPLANE ADVISORY FROM FSS. APPARENTLY NY ATC HAD ADVISED FSS OF RADIO OUT SIT BEFORE RECEIVING MY LAND LINE CALL AND FSS WAS COMMENCING GND CHK PRIOR TO LAUNCHING SAR. SUBSEQUENT TESTING OF ACFT COULD NOT RECREATE COM PROB WHICH MAY HAVE RESULTED FROM LOOSE AUDIO PANEL OR OVERHEATED RADIOS.