RADIO PROBLEM CAUSED DISTR AND PLT PENETRATED TCA BEFORE RECEIVING CLRNC.

Narrative

WHILE CRUISING AT 5500' MSL ENRTE FROM FRIDAY HARBOR TO BFI; I EXPERIENCED A FAILURE OF MY PRIMARY NAV RADIO; A NARCO RNAV. AT THE TIME I WAS IN CONTACT WITH ZSE FOR VFR FLT FOLLOWING. IN THE PROCESS OF DETERMINING THE PROB I NOTICED MY HEADSETS WERE RECEIVING AUDIO (AND NOT XMITTING) FROM COM 2 AND NAV 2 ONLY. I THEN TESTED AND RESET THE PANEL SWITCHES IN AN EFFORT TO BRING COM 1 BACK ON-LINE. COM 1 CAME BACK ON-LINE; HOWEVER NAV 1 (RNAV) REMAINED INOP. AS COM 1 CAME BACK ON-LINE; I HEARD ZSE CALL; STATING THIS WAS THE FOURTH CALL. I HAD MAINTAINED A VIS SCAN DURING OUR RADIO SILENCE AND THERE WAS NOT ANY TFC CONFLICT. ZSE CLRED ME TO OPERATE WITHIN THE TCA AND REQUESTED I CONTACT SEA APCH. AT THIS TIME; I WAS APPROX 1.5 MI AND 500' WITHIN THE SEA TCA. MODE C WAS OPERATING NORMALLY. HAD THE PROB AROSE DURING THE DAY OR DURING A BUSY TFC PERIOD I BELIEVE I WOULD HAVE NOTICED THE COM 1 PROB EARLIER; BUT SINCE RADIO CHATTER WAS LIGHT THAT EVENING I DID NOT SUSPECT A PROB. ONCE I DETERMINED THERE WAS A COM PROB; I THOUGHT I MIGHT HAVE TO SQUAWK 7600' IF I COULDN'T FIX THE XMITTING PROB WITHIN 30 SECS. I WAS AWARE OF MY POS AND DID BECOME CONCERNED SINCE THE TCA WAS SO CLOSE AND I HAD NOT RECEIVED CLRNC. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: CONTINUED FLT INTO TCA WHILE TRYING TO DETERMINE RADIO PROB IS MAJOR ERROR. COM LOSS WAS VERY BRIEF; CLRNC WAS VERY PROMPT.