What was found
AIRCRAFT WAS GNDED. BOTH HF RADIOS INOPERATIVE. UNABLE TO COMMUNICATE ON ALL FREQUENCY. TRIED TWO NEW HF TRANSCEIVERS, UNABLE TO TRANSMIT OR RECEIVE ON FREQUENCIES 6.640 & 11.342 MHZ, NYC & SFO STATIONS. INSPECTED FEED LINE INSIDE VERTICAL STABILIZER WITH NO DEFECTS NOTED IAW AMM 23-11-03 & 23-11-01, NO HELP. FURTHER TROUBLESHOOTING NEEDED. CONTINUED THE TROUBLESHOOTING BY ACCOMPLISHING SYS BITE WITH NO PROBLEMS NOTED IAW FIM 23-11-00-815-804 & PERFORMED A RADIO CHECK WITH SFO WITH NO PROBLEMS.