What was found
40 MIN INTO FLT AFTER ENTERING CLASS II NAV BUT PRIOR TO ETOPS AIRSPACE MADE POSITION REPORT NORMALLY ON HF1 RECEIVED SELCAL CHECK BUT COULD NOT RESPOND TO ATC. DISCOVERED THAT WE COULD NOT TRANSMIT ON HF OR VHF COMMS 1 OR 2 USING BOOM MIC OR HANDHELD MIC AT EITHER PILOT STATION. RECEVIED TRANSMISSIONS ON HF AND VHF AND FLIGHT INTERPHONE NORMALLY. AFTER 2 MINUTES ALL OPERATIONS RETURNED TO NORMAL FOR REMAINDER OF FLIGHT. FOUND NR 1 HF TO BE THE PROBLEM ON NR 1 HF AND NR 2 HF NR 1 HF SIDE. REPLACED NR 1 HF COUPLER. REF 23 11 61. PERFORMED OPS CK OF NR 1 HF PER 23 11 00. ON LEFT NR 1 HF AND RT SIDE NR 1 HF SYSTEM. VERIFIED NR 2 HF ON LEFT AND RT SIDE IS WORKING NML. REF 23 11 00.