As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 2 HF MAKES RANDOM KEYING SOUND DURING FLIGHT. CANNOT TRANSMIT ON THR NR 2 HF. RANDOM KEYING SOUND ONLY WHILE IN DATA MODE. ACFT GROUNDED. CONFIRMED THE NR 2 HF FAULT. REMOVED AND REPLACED HF ANTENNA COUPLER IAW AMM 23-11-61. PERFORMED AN HF SYSTEM TEST IAW AMM 23-11-00. ALL TESTS PASSED. OK FOR SERVICE.