What was found
HF1 TRANSMIT FUNCTION INOPERATIVE. AUDIO RECEPTION FUNCTIONS NORMALLY. ACFT GROUNDED. UNABLE TO DUPLICATE DEFECT, NR 1 HF OPS NORMAL. R & R NR 1 HF COUPLER REF MM 23-11-61, OPS CHECK NORMAL. REQUIRES FLIGHT VERIFICATION OF NR 1 HF. FLT VERIFICATION UNSUCCESSFUL. IAW VERIFYING FLIGHT CREW NR 1 HF FAILED ENROUTE CHECK. SFO RADIO COULD NOT HEAR US. WE COULD HEAR THEM. WE ONLY TRIED THE F/O CONTROL PANEL. ACCOMPLISHED FIM 23-11-00-810-806. ESTABLISHED COMMUNICATIONS AT 2330 LOCAL TIME ON FREQUENCY 5.547. CAPTAINS TRANSMIT AND RECEIVE GOOD FOR HF NR 1 AND HF NR 2. F/O TRANSMIT AND RECEIVE GOOD FOR HF NR 2, BUT F/O HF NR 1 TRANSMIT WAS UNREADABLE. F/O HF NR 1 RECEIVE WAS GOOD. REPLACED F/O AUDIO CONTROL PANEL REF MM23-51-02. INSTALLATION TEST OPS NORMAL. VERIFIED WITH SFO GOOD TRANSMIT AND RECEIVE OF HF NR 1 AND NR 2 FROM BOTH CAPTAIN AND F/O POSITION. FLIGHT VERIFICATION CK COMPLETED SUCCESSFULLY.