As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 1 HF RADIO UNABLE TO UNDERSTAND ATC DUE TO MODULATION. RECEIVED SELCAL OK. ATC HEARS OK. ATTEMPTED USE OF NR 1 HF RADIO LATER IN FLIGHT, NO ISSUES. ACFT GROUNDED. PERFORMED FIM TASK 23-11, TASK 23-11, TASK 801 AND HF OPS TEST IAW AMM 23-11-00 GROUND VERIFICATION NORMAL, OK FOR SERVICE.