WDB FREIGHTER LOST ALL VHF RADIO COM UNITS; HAD ONLY INTERMITTENT RECEPTION.

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BOTH HIGH FREQ RADIOS WERE GUARDING HONOLULU RADIO FREQS WITH SELCAL SELECTED TO THESE RADIOS. APPROX 100 MI W OF AWONE INTXN (50 MI S ST PAUL ISLAND) I REALIZED WE HADN'T BEEN HANDED OFF TO NEXT SECTOR. I LOOKED UP REMOTE FREQ FOR ST PAUL ISLAND; 127.6 AND SWITCHED OVER TO IT. I COULD IMMEDIATELY HEAR ZAN TRYING TO CALL US. I ATTEMPTED TO ANSWER BUT THEY WERE NOT RECEIVING US. TRIED OTHER 2 RADIOS BUT NO SUCCESS. AFTER MANY ATTEMPTS WE ESTABLISHED CONTACT VICINITY OF AWONE INTXN; AND WERE CLRED TO CLB FL350 DIRECT TO DLG VOR J511 AMOTT DIRECT ANC CONTACT ANC 124.8 OVER DLG. WE THEN RECEIVED A CALL FROM FLT SAYING THEY HAD BEEN TRYING TO CALL US ON 121.5 AND 128.95. THESE FREQS WERE TUNED ON #1 AND #3 VHF RADIOS BUT WE HEARD NOTHING. WE HAD 4 MORE OCCURRENCES OF INTERMITTENT XMITTING AND RECEIVING PRIOR TO LNDG ANC. EACH TIME WE TRIED ALL 3 RADIOS AND MADE SEVERAL ATTEMPTS ON EACH BEFORE ESTABLISHING CONTACT. ON ARR ANC WE WROTE UP ALL 3 RADIOS IN ACFT MAINT LOG. LATER I TALKED TO ONE OF OUR MECHS WHO HAD BEEN ON THIS AIRPLANE FROM SYDNEY AUSTRALIA TO TAIPEI. THIS AIRPLANE WAS LOADED WITH LIVE CATTLE WHICH WERE PUT ON THE AIRPLANE APPROX 2 1/2 HRS PRIOR TO DEP. ACFT MADE A GUAM FUEL STOP AND INCURRED AN ADDITIONAL 1 HR DELAY DUE TO APU PROBLEM. I THEREFORE BELIEVE AN EXCESSIVE AMOUNT OF MOISTURE WAS ABSORBED INTO RADIO RACK LOCATED UNDER FORWARD END OF MAIN DECK CARGO FLOOR. THIS IS ONLY REASON ALL 3 RADIOS COULD MALFUNCTION SINCE THEY ARE ALL INDEPENDENT UNITS AND SHARE NOTHING IN COMMON. AS FOR THE HUMAN FACTORS CONCERNED HERE: FROM THE VARIOUS COMMENTS WE SPORADICALLY RECEIVED FROM ZAN TALKING TO OUR OTHER FLTS AND ALSO FROM COMMENTS MADE TO US THEY EVIDENTLY THOUGHT WE WERE NOT PAYING ATTN OR MAINTAINING APPROPRIATE LISTENING WATCH. FROM MY PERSPECTIVE I THOUGHT THEY HAD FORGOTTEN TO HAND US OFF; WERE WORKING TOO MANY FREQS AT ONCE AND WERE NOT PAYING ATTN TO OUR CALLS. IT DID NOT OCCUR TO US OR ZAN THAT WE WERE LOSING ALL 3 VHF RADIOS. AFTER 3 MORE OCCURRENCES WE FINALLY REALIZED WE WERE INDEED LOSING ALL 3 RADIOS AND SO INFORMED ZAN. THEY SOUNDED AS THOUGH THEY DID NOT BELIEVE US. IF ZAN HAD CONSIDERED OUR VHF COM FAILURE THEY COULD HAVE ATTEMPTED TO SELCAL US THROUGH HONOLULU RADIO ON HIGH FREQ FREQS. IF WE HAD REALIZED EARLY ENOUGH WE HAD VHF COM FAILURE WE COULD HAVE CALLED HNL RADIO ON HIGH FREQ. IT IS IMPORTANT TO NOTE THAT OUR VHF RADIOS HAD NOT TOTALLY FAILED; BUT WERE INTERMITTENT WHICH IS EXTREMELY DIFFICULT TO RECOGNIZE.