What was found
COULD NOT TRANSMIT HF2 FREQUENCIES 6.640 AND 11.342 FROM CAPTAIN'S OR F/O'S RADIO PANEL. ACFT GROUNDED. COULD NOT ISOLATE FAULT TO NR 1 COUPLER BY REMOVING POWER FROM SYS 1 AND TRANSMITTING ON NR 2 PER ENGINEERING NOTE IN PREVIOUS T/S. DUE TO HISTORY REPLACED HF SYS NR 1 COUPLER AND HF TRANSCEIVER IAW AMM 23-11-61/401 AND 23-11-21/401, ETOPS SIGNIFICANT SYSTEM GROUND VERIFICATION SUCCESSFUL. ALSO DUE TO HISTORY REPLACED HF SYS NR 2 COUPLER AND HF TRANSCEIVER IAW AMM 23-11-61/401 AND 23-11-21/401, ETOPS SIGNIFICANT SYSTEM GROUND VERIFICATION SUCCESSFUL. THIS CLEARS MEL 23-11A.