As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ETOPS VERIFICATION FLIGHT FOR HF1 UNSATISFACTORY- HF1 TESTED WITH SFO RADIO ARINC AND THEY REPORTED THAT OUR TRANSMISSIONS WERE WEAK AND UNREADABLE. TESTED ON MULTIPLE FREQUENCIES. SENSITIVITY WAS SET TO 100- HF1 TUNING TOOK SLIGHTLY LONGER THAN NORMAL AS WELL. GROUNDED - YES. REMOVED AND REPLACED HF1 COUPLER REF B737-800 AMM 23-11-61 OP CK GOOD.